GLOSSARY

A

5' VNTR.

A specific variation outside the insulin gene that is implicated in NIDDM and IDDM susceptibility.

AADC INHIBITORS.

Drugs that block the amino acid decarboxylase; one type of enzyme that breaks down dopamine. Also called DC inhibitors, they include carbidopa and benserazide.

ABDOMINAL HERNIA.

Bulging of an organ or tissue through the muscle of the stomach wall.

ABDUCENS NERVE.

Cranial nerve VI; the nerve that extends from the midbrain to the lateral rectus muscle of the eye and controls movement of the eye toward the ear (abduction).

ABDUCTION.

Turning away from the body.

ABSCESS.

A localized collection of pus or infection that is walled off from the rest of the body.

ABSENCE SEIZURE.

A brief seizure with an accompanying loss of awareness or alertness.

ACAMPROSATE.

An anti-craving medication used in Europe to reduce the craving for alcohol. It is presently undergoing tests for approval in the United States.

ACANTHOCYTOSIS.

The presence of acanthocytes in the blood. Acanthocytes are red blood cells that have the appearance of thorns on their outer surface.

ACANTHOSIS NIGRICANS.

A skin condition characterized by darkly pigmented areas of velvety wart-like growths. Acanthosis nigricans usually affects the skin of the armpits, neck, and groin.

ACCOMMODATION.

The ability of the lens to change its focus from distant to near objects. It is achieved through the action of the ciliary muscles that change the shape of the lens.

ACETYLCHOLINE.

A neurotransmitter (chemical messenger) used to certain nerve cells to send messages to adjacent cells.

ACETYLCHOLINESTERASE (ACHE).

An enzyme found in nerve tissue.

ACHROMATOPSIA.

The inability to distinguish any colors.

ACID MALTASE.

The enzyme that regulates the amount of glycogen stored in muscle cells. When too much glycogen is present, acid maltase is released to break it down into waste products.

ACIDOSIS.

A condition of decreased alkalinity resulting from abnormally high acid levels (low pH) in the blood and tissues. Usually indicated by sickly sweet breath, headaches, nausea, vomiting, and visual impairments.

ACONDROPLASIA.

An autosomal dominant form of dwarfism caused by a defect in the formation of cartilage at the ends of long bones. Affected individuals typically have short limbs, a large head with a prominent forehead and flattened profile, and a normal-sized trunk.

ACQUIRED ANGIONEUROTICEDEMA.

Abbreviated AANE, or AAE, this is a non-hereditary form of angio edema that generally begins to show symptoms in, or after, the fourth decade of life.

ACQUIRED IMMUNITY.

Also called "specific immunity," refers to immune reaction mediated by B-cells and/or T-cells. Includes humoral and cellular immunity.

ACROCENTRIC.

A chromosome with the centromere positioned at the top end.

ACROCEPHALOPOLYSYNDACTYLY SYNDROMES.

A collection of genetic disorders characterized by cone shaped abnormality of the skull and partial fusing of adjacent fingers or toes.

ACROCEPHALY.

An abnormal cone shape of the head.

ACROMELIC.

The anatomical term used to denote the end of a limb (arm or leg). In the context of Robinow syndrome, it refers to bones of the hands and feet.

ACROOSTEOLYSIS.

Loss of bone tissue at the ends of the fingers and/or toes.

ACROPARESTHESIAS.

Painful burning sensation in hands and feet.

ACTION POTENTIAL.

The wave-like change in the electrical properties of a cell membrane, resulting from the difference in electrical charge between the inside and outside of the membrane. The action potential acts as a signal for certain activities and processes in the body.

ACUPUNCTURE.

An alternative health procedure based on ancient Chinese methods, involving insertion of thin needles at specific pressure points in the body.

ACUTE PHASE REACTANTS.

Blood proteins whose concentrations increase or decrease in reaction to the inflammation process.

ACUTE PHASE.

The initial phase of LHON where visual blurring begins in both eyes, and central vision is lost.

ADDUCTED THUMBS.

Thumbs clasped across the palm.

ADDUCTION.

Movement toward the body. In Duane retraction syndrome, turning the eye inward toward the nose.

ADENOCARCINOMA.

A type of cancer which is in a gland-like form.

ADENOMATOUS.

Derived from glandular structures

ADRENAL.

A pair of glands located on top of the kidneys that secrete substances or hormones, like steroids and adrenaline, which regulate various functions, such as water balance and stress response.

ADRENAL GLAND.

A triangle-shaped endocrine gland, located above each kidney, that synthesizes aldosterone, cortisol, and testosterone from cholesterol. The adrenal glands are responsible for salt and water levels in the body, as well as for protein, fat, and carbohydrate metabolism.

ADRENAL INSUFFICIENCY.

Problems with the adrenal glands that can be life threatening if not treated. Symptoms include sluggishness, weakness, weight loss, vomiting, darkening of the skin and mental changes.

ADRENOCORTICOTROPIN (CORTICOTROPHIN).

A hormone that acts on cells of the adrenal cortex, causing them to produce male sex hormones and hormones that control water and mineral balance in the body.

ADVANCED BONE AGE.

The bones, on x-ray, appear to be those of an older individual.

ADYSPLASIA.

A term referring to the combination of renal agenesis (complete absence of one or both kidneys) and renal dysplasia (developmental anomaly of the kidney).

AFFECTIVE FLATTENING.

A loss or lack of emotional expressiveness. It is sometimes called blunted or restricted affect.

AFLATOXIN.

A substance produced by molds that grow on rice and peanuts. Exposure to aflatoxin is thought to explain the high rates of primary liver cancer in Africa and parts of Asia.

AGE-ASSOCIATED MEMORY IMPAIRMENT (AAMI).

A condition in which an older person suffers some memory loss and takes longer to learn new information. AAMI is distinguished from dementia in that it is not progressive and does not represent a serious decline from the person's previous level of functioning.

AGENESIS.

Failure of an organ, tissue or cell to develop or grow.

AGENESIS OF THE CORPUS CALLOSUM.

Failure of the corpus callosum to form and develop. The corpus callosum is the band of nerve fibers located between the two sides, or hemispheres, of the brain.

AGNOSIA.

Loss of the ability to recognize objects by use of the physical senses.

AGYRI.

A lack of convolutions (gyri) or normal folds in the brain tissue.

AKATHISIA.

Agitated or restless movement, usually affecting the legs and accompanied by a sense of discomfort. It is a common side effect of neuroleptic medications.

AKINESIA.

A loss of the ability to move; freezing in place.

ALKALINE.

Having a basic pH; not acidic.

ALKALINIZATION.

The process of making a solution more basic, rather than more acidic, by raising the pH.

ALLELE.

One of two or more alternate forms of a gene.

ALLELIC.

Related to the same gene.

ALLELIC VARIANTS.

A disease is said to have allelic variants when different mutations in the same allele result in identical, or nearly identical, symptoms. An allele is the combined locations of a gene on the two paired chromosomes that contain this gene.

ALLERGEN.

A substance or organism foreign to the body; allergens stimulate the immune system to produce antibodies.

ALLERGIC RHINITIS.

Hay fever.

ALLERGY.

Condition in which immune system is hypersensitive to contact with allergens; an abnormal response by the immune system to contact with an allergen; condition in which contact with allergen produces symptoms such as inflammation of tissues and production of excess mucus in respiratory system.

ALLOSTERIC ACTIVATOR SITE.

Site at which an enzyme is regulated separate from its site of catalytic enzymatic activity.

ALOPECIA AREATA.

A nonscarring hair loss syndrome characterized by smooth round or oval hairless areas on the scalp.

ALOPECIA.

Loss of hair or baldness.

ALPHA-FETOPROTEIN (AFP).

A chemical substance produced by the fetus and found in the fetal circulation. AFP is also found in abnormally high concentrations in most patients with primary liver cancer.

ALPHA-L-IDURONIDASE..

An enzyme that breaks down dermatan sulfate and heparan sulfate. People with Hurler syndrome do not make enough of this enzyme.

ALPHA-THALASSEMIA.

Autosomal recessive disorder where no functional hemoglobin is produced. Leads to severe untreatable anemia.

ALTERATION.

Change or mutation in a gene, specifically in the DNA that codes for the gene.

ALTERNATE COMPLEMENT PATHWAY.

A cascade of enzymatic reactions that produce antibacterial proteins. This pathway helps to ward off infections.

ALZHEIMER DISEASE.

A neurodegenerative disease marked by the loss of cognitive ability, generally over a period of 10–15 years, associated with the development of abnormal tissues and protein deposits in the brain.

AMASTIA.

A birth defect involving absent breast(s).

AMBIGUOUS.

Unclear or open to more than one interpretation.

AMELOGENESIS IMPERFECTA.

A hereditary dental defect characterized by discoloration of the teeth.

AMINO ACID.

Organic compounds that form the building blocks of protein. There are 20 types of amino acids (eight are "essential amino acids" which the body cannot make and must therefore be obtained from food).

AMNIOCENTESIS.

A procedure performed between 16 and 18 weeks of pregnancy in which a needle is inserted through a woman's abdomen into the uterus to draw out a small sample of the amniotic fluid from around the fetus; either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus.

AMNION.

The thin, protective sac that suspends the fetus in a protective amniotic fluid.

AMNION.

Thin, tough innermost layer of the amniotic sac.

AMNIOTIC FLUID.

The liquid in the amniotic sac that cushions the fetus and regulates temperature in the placental environment. Amniotic fluid also contains fetal cells.

AMNIOTIC SAC.

The membranous sac that contains the fetus and the amniotic fluid during pregnancy.

AMNIOTIC SAMPLE.

Sample of amniotic fluid, the protective fluid surrounding a fetus in the womb.

AMPLIFICATION.

A process by which something is made larger. In clotting, only a very few chemicals are released by the initial injury; they result in a cascade of chemical reactions which produces increasingly larger quantities of different chemicals, resulting in an appropriately-sized, strong fibrin clot.

AMPUTATION.

Surgical removal of any portion of the body.

AMYLASE.

A digestive enzyme found in saliva or pancreatic fluid that breaks down starch and sugars.

AMYLOID.

A waxy translucent substance composed mostly of protein, that forms plaques (abnormal deposits) in the brain.

AMYLOIDOSIS.

Accumulation of amyloid deposits in various organs and tissues in the body such that normal functioning of an organ is compromised.

AMYOPLASIA.

The mildest form of arthrogryposis muliplex congenita, characterized by sporadic and recurrent contractures of the wrists, elbows, and knees; club feet, and an abnormal internal rotation of the shoulders.

AMYOTROPHIC LATERAL SCLEROSIS (ALS).

A neurodegenerative disease that is caused by degeneration of the motor fibers and neurons in the brain, brainstem, and spinal cord, leading to stiffness, weak muscles, and respiratory failure. Also called Lou Gehrig's disease.

ANAGEN.

The growth phase of the human hair growth cycle.

ANALYTE.

A chemical substance such as an enzyme, hormone, or protein.

ANDROGENS.

A group of steroid hormones that stimulate the development of male sex organs and male secondary sexual characteristics.

ANEMIA.

A condition in which there is an abnormally low number of red blood cells in the bloodstream. It may be due to loss of blood, an increase in red blood cell destruction, or a decrease in red blood cell production. Major symptoms are paleness, shortness of breath, unusually fast or strong heart beats, and tiredness.

ANESTHESIA.

Lack of normal sensation (especially to pain) brought on by medications just prior to surgery or other medical procedures.

ANESTHETIC.

Drug used to temporarily cause loss of sensation in an area of the body. An anesthetic may either be general, associated with a loss of consciousness, or local, affecting one area only without loss of consciousness. Anesthetics are administered either via inhalation or needle injection.

ANEUPLOIDY.

Having too many or too few copies of a specific chromosome; the most common forms are trisomy (three) and monosomy (one); two copies of a chromosome is normal.

ANEURYSM.

Widening of an artery, which could eventually bleed.

ANGELMAN SYNDROME.

A syndrome caused by a deletion in the maternally inherited chromosome 15 or uniparental disomy of the paternal chromsome 15.

ANGIOGRAPHY.

Radiographic examination of blood vessels after injection with a radiopaque contrast substance or dye.

ANGIOID STREAKS.

Gray, orange, or red wavy branching lines in Bruch's membrane.

ANGIOKERATOMA.

Skin rash comprised of red bumps. Rash most commonly occurs between the belly button and the knees.

ANGIOMA.

A benign tumor composed of blood vessels or lymph vessels.

ANGIONEUROTIC EDEMA.

Recurrent episodes of swelling of the tissues of the body caused by an overactive immune system. This is aslo called angioedema.

ANGIOTENSINOGEN.

A plasma globulin (protein) formed in the liver and directly involved in the regulation of blood pressure.

ANKYLOSIS.

Immobility of a joint due to the formation of new bone at the site of inflammation.

ANOMALOUS VENOUS RETURN.

Normally, the veins that bring blood containing oxygen from the lungs to the heart (called pulmonary veins) are connected to the left atrium. In this situation, the pulmonary veins are connected to the right atrium.

ANOMALOUS.

Irregular or different from normal.

ANOMALY.

Generally, something that is different from what is normal or expected. More specifically in medicine, a malformation or abnormality in any part of the body.

ANOPTHALMIA.

A medical condition in which one eye is missing.

ANOTIA.

Absence of an ear.

ANTERIOR FONTANELLE.

The soft-spot on the skull of an infant that is located in the center of the head just behind the hairline.

ANTERIOR HORN CELLS.

Subset of motor neurons within the spinal cord.

ANTI-ANDROGEN DRUGS.

Drugs that block the activity of the male hormone.

ANTIBIOTICS.

A group of medications that kill or slow the growth of bacteria.

ANTIBODY.

A special protein made by the body's immune system as a defense against foreign material (bacteria, viruses, etc.) that enters the body. It is uniquely designed to attack and neutralize the specific antigen that triggered the immune response.

ANTICIPATION.

The apparent tendency of certain diseases to appear at earlier ages and with increasing severity in successive generations.

ANTICOAGULANT.

Drugs used to prevent blood clots.

ANTIDIURETIC HORMONE (VASOPRESSIN).

A hormone that acts on the kidneys to regulate water balance.

ANTIGEN.

A substance or organism that is foreign to the body and stimulates a response from the immune system.

ANTIGEN PRESENTING CELL.

Cells that are able to present foreign antigen in conjunction with MHC proteins to the immune system.

ANUS.

The opening at the end of the intestine that carries waste out of the body

AORTA.

The main artery located above the heart which pumps oxygenated blood out into the body. Many congenital heart defects affect the aorta.

AORTIC REGURGITATION.

A condition in which the aortic valve does not close tightly, allowing blood to flow backwards from the aorta into the heart.

AORTIC ROOT.

The location where the aorta (main heart blood vessel) inserts in the heart. Enlargement of the aortic root can cause it to rupture.

AORTIC STENOSIS.

A condition in which the aortic valve does not open properly, making it difficult for blood to leave the heart.

APHASIA.

The loss of the ability to speak or to understand written or spoken language. A person who cannot speak or understand language is said to be aphasic.

APLASIA.

Defective development resulting in absence of all or part of an organ or tissue.

APLASTIC ANEMIA.

A form of anemia characterized by a greatly decreased formation of red and white blood cells as a result of abnormal bone marrow.

APNEA.

An irregular breathing pattern characterized by abnormally long periods of the complete cessation of breathing.

APOENZYME.

An enzyme that cannot function without assistance from other chemicals called cofactors.

APOPTOSIS.

The normally programmed cell death process in which cells die in order to be replaced with new cells.

APPENDECTOMY.

The procedure to surgically remove an appendix.

APPENDICITIS.

Inflammation of the appendix.

APPENDIX.

A portion of intestine attached to the cecum.

APRAXIA.

Impairment of the ability to make purposeful movements, but not paralysis or loss of sensation.

AQUEOUS HUMOR.

A fluid produced by the ciliary body and contained within the front chamber of the eye.

ARACHNODACTYLY.

A condition characterized by abnormally long and slender fingers and toes.

ARNOLD-CHIARI MALFORMATION.

A congenital anomaly in which parts of the brain protrude through the opening in the base of the skull into the spinal column.

ARRHYTHMIA.

Abnormal heart rhythm, examples are a slow, fast, or irregular heart rate.

ARTERIAL.

Term used to describe an artery or the entire system of arteries.

ARTERIOLE.

The smallest type of artery.

ARTERIOPATHY.

Damage to blood vessels.

ARTERIOSCLEROSIS.

Hardening of the arteries that often results in decreased ability of blood to flow smoothly.

ARTERIOVENOUS MALFORMATION (AVM).

Abnormal, direct connection between the arteries and veins (blood vessels). Can range from very small to large in size. Bleeding or an aneurysm may result.

ARTERY.

A blood vessel that carries blood away from the heart to peripheral tissues.

ARTHROCHALASIA.

Excessive loosness of the joints.

ARTHROGRYPOSIS.

Abnormal joint contracture.

ASPERGER SYNDROME.

A term used to describe high-functioning individuals with autism. These individuals usually have normal IQ and some language skills.

ASPHYXIA.

Lack of oxygen. In the case of cerebral palsy, lack of oxygen to the brain.

ASPIRATION PNEUMONIA.

Lung infection due to food or liquids accidentally getting into lungs.

ASPIRATION.

Inhalation of food or saliva.

ASPLENIA.

The absence of the spleen in the body.

ASSOCIATION.

A non-random occurrence in two or more individuals of the same group of anomalies that are not otherwise known to be a sequence or syndrome.

ASTIGMATISM.

A cause of poor eyesight, usually due to an error in the refraction of light within the eye.

ASTROCYTOMA.

Tumor of the central nervous system derived from astrocytes

ASYMMETRIC SEPTAL HYPERTROPHY.

A condition in which the septum (the wall that separates the atria of the heart) is abnormally excessively thickened. In microscopic examination, normal alignment of muscle cells is absent (myocardial disarray).

ASYMMETRY.

Without symmetry, as when a disease, condition, or symptom is not manifested equally on both sides of the body or body part.

ASYMPTOMATIC.

Without symptoms.

ASYMPTOMATIC CARRIER.

A person who carries a recessive trait but does not show any characteristics of the trait.

ATAXIA.

A condition marked by impaired muscular coordination, most frequently resulting from disorders in the brain or spinal cord.

ATHEROSCLEROSIS.

Hardening of the arteries caused by cholesterol and fat deposits. Increases risk of heart disease, stroke, and other complications.

ATHETOSIS.

A condition marked by slow, writhing, involuntary muscle movements.

ATOPIC.

A condition or disease that is the result of an allergic reaction.

ATOPIC ASTHMA.

Asthma caused by an allergic reaction; atopic asthma tends to have a strong inherited component (tends to run in families).

ATOPIC RHINITIS.

Also referred to as "hay fever"; symptoms of rhinitis caused by an allergic response to the presence of an allergen (such as tree or grass pollen).

ATP.

Adenosine triphosphate. The chemical used by the cells of the body for energy.

ATRESIA.

An abnormal condition in which a structure that should be hollow is fused shut.

ATRIA/ATRIUM.

The upper chamber of the heart. Typically, there are two atrias, one on the right side and one on the left side of the heart.

ATRIAL SEPTAL DEFECT (ASD).

An abnormal opening between the two upper chambers (atria) of the heart.

ATROPHIC DERMATOSIS.

Wasting away of the skin.

ATROPHIC PHASE.

The final phase of LHON where cells in the optic disc and optic nerve have atrophied, resulting in legal blindness. Peripheral vision remains.

ATROPHY.

The wasting away or decrease in size of a cell, tissue, organ, or part of the body caused by lack of nourishment, inactivity, or loss of nerve supply.

ATTENTION DEFICIT HYPERACTIVITY DISORDER (ADHD).

A condition in which a person (usually a child) has an unusually high activity level and a short attention span. People with the disorder may act impulsively and may have learning and behavioral problems.

ATYPIA.

Lacking uniformity.

ATYPICAL PERSONALITY DEVELOPMENT.

Another term for pervasive development disorder (PDD-NOS). Other synonyms for this diagnostic category are atypical autism and atypical PDD.

AUDIOGRAM.

A graph of hearing level versus frequency. An audiologist plots the hearing loss of a patient on this graph to help to determine the type of hearing loss and possible treatments.

AUDITORY NERVE.

The nerve responsible for transmitting electrical impulses created within the ear in response to sounds to the brain.

AURICULO.

Related to the ear.

AUTISM.

A developmental disability that appears early in life, in which normal brain development is disrupted and social and communication skills are retarded, sometimes severely.

AUTISTIC PSYCHOPATHY.

Hans Asperger's original name for Asperger syndrome, which is still used occasionally as a synonym for the disorder.

AUTISTIC SPECTRUM DISORDERS.

Another term for the pervasive developmental disorders.

AUTOANTIBODY.

An antibody that reacts against part of the self.

AUTOIMMUNE.

Referring to an immune reaction erroneously directed toward 'self' tissues.

AUTOIMMUNE DISORDER.

One of a group of disorders, like rheumatoid arthritis and systemic lupus erythematosus, in which the immune system is overactive and has lost the ability to distinguish between self and non-self. The body's immune cells turn on the body, attacking various tissues and organs.

AUTONOMIC NERVOUS SYSTEM.

The part of the nervous system that regulates heart muscle, smooth muscle, and glands.

AUTOSOMAL.

Relating to any chromosome besides the X and Y sex chromosomes. Human cells contain 22 pairs of autosomes and one pair of sex chromosomes.

AUTOSOMAL DISEASE.

A disease caused by a gene located on an autosomal chromosome.

AUTOSOMAL DOMINANT.

A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. A person with an autosomal dominant disorder has a 50% chance of passing it to each of his or her offspring.

AUTOSOMAL RECESSIVE.

A pattern of inheritance in which both copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. When both parents have one abnormal copy of the same gene, they have a 25% chance with each pregnancy that their offspring will have the disorder.

AXON.

Skinny, wire-like extension of nerve cells.

B

B CELL.

Specialized type of white blood cell that is capable of secreting infection-fighting antibodies.

BALANCED CHROMOSOME TRANSLOCATION.

A rearrangement of the chromosomes in which two chromosomes have broken and exchanged pieces without the loss of genetic material.

BAND.

A specific region of a chromosome that is identified by its characteristic staining pattern and location within a chromosome, as seen in a karyotype. A band is either part of the short arm (p arm) or the long arm (q arm) of a chromosome and is further defined by a numeric location, such as chromosome band 11q24.1.

BARIUM ENEMA X RAY.

A procedure that involves the administration of barium into the intestines by a tube inserted into the rectum. Barium is a chalky substance that enhances the visualization of the gastrointestinal tract on x ray.

BARIUM.

A chemical put into a solution and swallowed to help with outlining the gastrointestinal system during an x-ray study.

BASAL CELL CARCINOMA.

A cancer originating from skin.

BASAL GANGLIA.

A section of the brain responsible for smooth muscular movement.

BASE PAIRS.

Building blocks of DNA, the chemical that genes are made of.

BASEMENT MEMBRANE.

Part of the epithelium, or outer layer of the cornea.

BECKER MUSCULAR DYSTROPHY (BMD).

A type of muscular dystrophy that affects older boys and men, and usually follows a milder course than Duchenne muscular dystrophy.

BECKWITH-WIEDEMANN SYNDROME.

A collection of health problems present at birth including an omphalocele, large tongue, and large body size.

BENIGN.

A non-cancerous tumor that does not spread and is not life-threatening.

BENIGN PROSTATIC HYPERPLASIA (BPH).

A noncancerous condition of the prostate that causes growth of the prostate tissue, thus enlarging the prostate and blocking urination.

BENIGN TUMOR.

An abnormal proliferation of cells that does not spread to other sites.

BENZOQUINONE ACETIC ACID.

Toxic compound that is formed when oxygen reacts with homogentisic acid.

BETA-2 MICROGLOBULIN.

A component protein of class I MHC.

BETA-ADRENERGIC BLOCKER.

A drug that works by controlling the nerve impulses along specific nerve pathways.

BETA CELLS.

Specialized cells of the pancreas that make insulin.

BIFID UVULA.

The uvula is the small, tear drop–shaped piece of flesh hanging in the back of the throat; the uvula is bifid if the bottom area is split in two parts.

BILATERAL.

Relating to or affecting both sides of the body or both of a pair of organs.

BILATERAL BREAST CANCER.

Cancer of both breasts, caused by two separate cancer processes.

BILE.

A substance produced by the liver, and concentrated and stored in the gallbladder. Bile contains a number of different substances, including bile salts, cholesterol, and bilirubin.

BILE ACIDS.

Steroid acids such as cholic acid that occur in bile, an alkaline fluid secreted by the liver and passed into a part of the small intestine where it aids in absorption of fats.

BILE ALCOHOL.

A steroid acid with an alcohol group attached.

BILE DUCT.

A passageway that carries bile (fluid secreted by the liver involved in fat absorption) from the liver to the gallbladder to the small intestine.

BILIRUBIN.

A yellow pigment that is the end result of hemoglobin breakdown. This pigment is metabolized in the liver and excreted from the body through the bile. Bloodstream levels are normally low; however, extensive red cell destruction leads to excessive bilirubin formation and jaundice.

BIOCHEMICAL TESTING.

Measuring the amount or activity of a particular enzyme or protein in a sample of blood or urine or other tissue from the body.

BIOFEEDBACK.

A technique in which patients are trained to gain some voluntary control over certain physiological conditions, such as blood pressure and muscle tension, and to promote relaxation.

BIOPSY.

The surgical removal and microscopic examination of living tissue for diagnostic purposes.

BIOPTICS.

Glasses that have small telescopes fitted in the lens.

BIOSYNTHESIS.

The manufacture of materials in a biological system.

BIOTIN.

A growth vitamin of the vitamin B complex found naturally in liver, egg yolks, and yeast.

BIPOLAR DISORDER.

Formerly called "manic depression," this psychological disorder is characterized by periods of mania followed by periods of depression.

BITEMPORAL CONSTRICTION.

Abnormal narrowing of both sides of the forehead.

BLACKFAN-DIAMOND SYNDROME (BDS).

A disorder with congenital hypoplastic anemia. Some researchers believe that some or all individuals with Aase syndrome actually have BDS, that Aase syndrome and BDS are not separate disorders.

BLADDER.

This is the organ that stores urine after it flows out of the kidneys and through the ureters.

BLEPHAROPHIMOSIS.

A small eye opening without fusion of the upper eyelid with the lower eyelid at the inner and outer corner of the eye.

BLEPHAROSPASM.

A focal dystonia marked by excessive blinking and involuntary closing of the eyes.

BLOOD VESSELS.

General term for arteries, veins, and capillaries which transport blood throughout the body.

BODY ASYMMETRY.

Abnormal development of the body in which the trunk and/or the limbs are not of equal size from one side of the body to the other.

BODY MASS INDEX (BMI).

Assessment of health related to weight and height.

BOILS.

Painful areas of inflammation.

BONE DYSPLASIA.

Abnormal bone development.

BONE MARROW TRANSPLANT (BMT).

A medical procedure used to treat some diseases that arise from defective blood cell formation in the bone marrow. Healthy bone marrow is extracted from a donor to replace the marrow in an ailing individual. Proteins on the surface of bone marrow cells must be identical or very closely matched between a donor and the recipient.

BONE MARROW.

A spongy tissue located in the hollow centers of certain bones, such as the skull and hip bones. Bone marrow is the site of blood cell generation.

BONE REMODELING.

The process of breaking down old bone and building up new bone.

BONE SCLEROSIS.

Increased bone density and hardness.

BOTULINUM TOXIN.

A class of neurotoxins that are produced by a bacteria and that cause paralysis and weakness of muscles.

BOWMAN'S LAYER.

Transparent sheet of tissue directly below the basement membrane.

BOY IN THE BUBBLE.

A description for SCID since these children need to be isolated from exposure to germs, until they are treated by bone marrow transplantation or other therapy.

BRACHYCEPHALY.

An abnormal thickening and widening of the skull.

BRACHYDACTYLY.

Abnormal shortness of the fingers and toes.

BRACHYMELIA.

A general medical term used to describe short limbs.

BRADYKINESIA.

Extremely slow movement.

BRAILLE.

An alphabet represented by patterns of raised dots which may be felt with the fingertips. It is the main method of reading used by the blind today.

BRAIN VENTRICLES.

A set of four connected cavities that are located deep in the core of the brain. Cerebrospinal fluid is made by cells lining the walls of the first two ventricles, then flows through the third, then fourth ventricle before flowing out of the brain. The fluid-filled cavities provide mechanical cushion for the brain, and the CSF provides nutrients to, and carries metabolic wastes away from, the cells of the brain.

BRANCHED-CHAIN.

An open chain of atoms having one or more side chains.

BRANCHING ENZYME.

Enzyme responsible for building the branched structure of glycogen stores.

BRCA1 AND BRCA2.

Genes that encode for proteins that supress tumor growth. Inherited mutations in these genes have been associated with hereditary forms of breast cancer.

BREAST BIOPSY.

Small sample of tissue taken from the breast and studied, to diagnose and determine the exact type of breast cancer.

BREAST SELF-EXAM (BSE).

Examination by an individual of their own breasts.

BREECH DELIVERY.

Birth of an infant feet or buttocks first.

BROAD LIGAMENT.

The ligament connecting the ovaries to the uterus.

BRONCHI.

Branching tube-like structures that carry air in and out of the lungs; walls of bronchi contain circular muscles that can constrict (tighten up to make airways narrower) or dilate (relax to make airways wider); bronchi divide into smaller bronchioles within the lung tissue.

BRONCHIECTASIS.

An abnormal condition of the bronchial tree, characterized by irreversible widening and destruction of the bronchial walls of the lungs.

BRUCH'S MEMBRANE.

A membrane in the eye between the choroid membrane and the retina.

BRUTON TYROSINE KINASE (BTK).

An enzyme vital for the maturation of B cells.

BULBAR MUSCLES.

Muscles that control chewing, swallowing, and speaking.

BUNDLES OF PROBST.

Abnormally developed nerve fibers in the brain.

BUNION.

A bulge on the first joint of the big toe, caused by the swelling of a fluid sac under the skin.

BUPHTHALMOS.

A characteristic enlargement of one or both eyes associated with infantile glaucoma.

C

C1 INHIBITOR.

Abbreviated C1-INH, this protein is responsible for preventing the action of the C1 complement molecules in the body. It is this protein that is either deficient or malformed in HANE.

CA-125 (CARBOHYDRATE ANTIGEN 125).

A protein that is sometimes high when ovarian cancer is present. A blood sample can determine the level of CA-125 present.

CAESAREAN SECTION.

Surgical method to deliver a baby that requires making an incision in the mother's abdomen to remove the infant.

CAFÉ-AU-LAIT SPOTS.

Birthmarks that may appear anywhere on the skin; named after the French coffee drink because of the light-brown color of the marks.

CALCIFICATION.

A process in which tissue becomes hardened due to calcium deposits.

CALCITRIOL.

A substance that assists in bone growth by helping to maintain calcium and phosphate levels in the blood. Vitamin D is converted into this substance by the body.

CALCIUM.

One of the elements that make up the hydroxyapatite crystals found in bone.

CAMPTODACTYLY.

An abnormal permanent bending of one or more fingers or toes.

CANAVAN DISEASE.

A serious genetic disease more common in the Eastern European Jewish population that causes mental retardation and early death. Canavan disease is caused by the lack of an enzyme called aspartoacylase.

CANCER.

A disease caused by uncontrolled growth of the body's cells.

CANCER CELLS.

Have characteristics that distinguish them from normal cells and non-cancerous cells; they are threatening, harmful, and resistant to treatment

CANDIDATE GENE.

A gene that encodes proteins believed to be involved in a particular disease process.

CAPILLARY.

Very narrow tube that carries liquid like blood or lymphatic fluid.

CARBOHYDRATE.

Any of various natural compounds of carbon, hydrogen, and oxygen (as in sugars and starches) that are burned by the body for energy.

CARCINOGEN.

Any substance capable of causing cancer by mutating the cell's DNA.

CARCINOMA.

Any cancer that arises in the epithelium, the tissue that lines the external and internal organs of the body.

CARDIAC CONDUCTION DEFECT.

Abnormality of the electrical system of the heart that regulates the heartbeat.

CARDIAC MUSCLE.

The muscle of the heart.

CARDINAL SYMPTOMS.

A group of symptoms that define a disorder or disease.

CARDIOMYOPATHY.

A thickening of the heart muscle.

CARNITINE PALMITOYLTRANSFERASE (CPT).

An enzyme that transfers a palmitoyl group. CPT is a major regulatory enzyme of lipid metabolism, required for the transport of long-chain fatty acids across the inner mitochondria membrane. This transport depends on carnitine.

CARNITINE.

An amino acid necessary for metabolism of the long-chain fatty acid portion of lipids. Also called vitamin B7.

CARRIER.

A person who possesses a gene for an abnormal trait without showing signs of the disorder. The person may pass the abnormal gene on to offspring. Also refers to a person who has a particular disease agent present within his or her body, and can pass this agent on to others, but who displays no symptoms of infection.

CARRIER TESTING.

Testing performed to determine if someone possesses one changed copy and one unchanged copy of a particular gene.

CARTILAGE.

A tough, elastic connective tissue found in the joints, outer ear, nose, larynx, and other parts of the body.

CARTILAGE OLIGOMERIC MATRIX PROTEIN GENE.

A gene that codes for a specific protein involved in the formation of cartilage.

CASEIN HYDROLYSATE.

A preparation made from the milk protein casein, which is hydrolyzed to break it down into its constituent amino acids. Amino acids are the building blocks of proteins.

CATAGEN.

The breakdown phase of the hair growth cycle.

CATALYST.

A substance that changes the rate of a chemical reaction, but is not physically changed by the process.

CATALYZE.

Facilitate. A catalyst lowers the amount of energy required for a specific chemical reaction to occur. Catalysts are not used up in the chemical reactions they facilitate.

CATAPLEXY.

A symptom of narcolepsy in which there is a sudden episode of muscle weakness triggered by emotions. The muscle weakness may cause the person's knees to buckle, or the head to drop. In severe cases, the patient may become paralyzed for a few seconds to minutes.

CATARACT.

A clouding of the eye's lens or its surrounding membrane that obstructs the passage of light and causes blurred vision. Surgery may be performed to remove the cataract.

CATATONIC BEHAVIOR.

Behavior characterized by muscular tightness or rigidity and lack of response to the environment. In some patients rigidity alternates with excited or hyperactive behavior.

CATECHOLAMINES.

Biologically active compounds involved in the regulation of the nervous and cardiovascular systems, rate of metabolism, body temperature, and smooth muscle.

CATHETER.

A narrow, flexible tube used to create a pathway for introducing drugs, nutrients, fluids, or blood products into the body and/or for removing fluid or other substances from the body.

CATHETERIZATION.

The process of inserting a hollow tube into a body cavity or blood vessel.

CATIONIC TRYPSINOGEN GENE.

Gene known to cause hereditary pancreatitis when significantly altered.

CAUDAL.

Pertaining to the tail (bone).

CAUTERIZATION.

Process of burning tissue either with a laser or electric needle to stop bleeding or destroy damaged tissue.

CDKN2A OR P16.

A gene that encodes for the tumorsupressing proteins p16 and p19. When this gene is altered it is known to cause familial atypical multiple mole melanoma (FAMMM) syndrome and possibly increased pancreatic cancer risk.

CECUM.

The first part of the large bowel.

CELL.

The smallest living units of the body which group together to form tissues and help the body perform specific functions.

CELL ADHESION MOLECULE.

Any one of several thousand proteins that together control the cell-to-cell communication that must take place in order for cells to migrate to their proper places, develop into the proper types of cells, and make the appropriate connections with other cells.

CELLULAR IMMUNITY.

A type of acquired immunity mediated by killer T-cells; important in fighting "hidden" infections, such as those caused by cellular parasites and some viruses.

CENTRAL NERVOUS SYSTEM.

Part of the nervous system consisting of the brain, cranial nerves, and spinal cord. The brain is the center of higher processes, such as thought and emotion and is responsible for the coordination and control of bodily activities and the interpretation of information from the senses. The cranial nerves and spinal cord link the brain to the peripheral nervous system, that is the nerves present in the rest of body.

CENTRAL POLYDACTYLY.

Occurring between the thumb and little finger or between the big toe and the little toe.

CENTRAL VISION.

The ability to see objects located directly in front of the eye. Central vision is necessary for reading and other activities that require people to focus on objects directly in front of them.

CENTROMERE.

The constricted region of a chromosome. It performs certain functions during cell division.

CEREBELLAR ATAXIA.

Unsteadiness and lack of coordination caused by a progressive degeneration of the part of the brain known as the cerebellum.

CEREBELLUM.

The lower back part of the brain responsible for functions such as maintaining balance, and coordinating and controlling voluntary muscle movement.

CEREBRAL CORTEX.

The outer surface of the cerebrum made up of gray matter and involved in higher thought processes.

CEREBRAL PALSY.

Movement disability resulting from nonprogressive brain damage.

CEREBRAL VENTRICLES.

Spaces in the brain that are located between portions of the brain and filled with cerebrospinal fluid.

CEREBRO.

Related to the head or brain.

CEREBROSIDES.

Fatty carbohydrates that occur in the brain and nervous system.

CEREBROSPINAL FLUID.

The clear, normally colorless fluid that fills the brain cavities (ventricles), the subarachnoid space around the brain, and the spinal cord and acts as a shock absorber.

CEREBRUM.

The largest section of the brain, which is responsible for such higher functions as speech, thought, vision, and memory.

CEROID.

The byproduct of cell membrane breakdown.

CERULOPLASMIN.

A protein circulating in the bloodstream that binds with copper and transports it.

CERVICAL DYSTONIA.

A focal dystonia that causes neck muscles to contract involuntarily, leading to abnormal movements and posture of the head and neck. Also known as spasmodic torticollis.

CERVICITIS.

Inflammation of the cervix.

CERVICO-MEDULLARY JUNCTION.

The area where the brain and spine connect.

CFTR.

Cystic fibrosis transmembrane conductance regulator. The protein responsible for regulating chloride movement across cells in some tissues. When a person has two defective copies of the CFTR gene, cystic fibrosis is the result.

CGG OR CGG SEQUENCE.

Shorthand for the DNA sequence: cytosine-guanine-guanine. Cytosine and guanine are two of the four molecules, otherwise called nucleic acids, that make up DNA.

CHAPERONIN.

A molecule that captures and refolds misshapen proteins that might interfere with normal cellular functions; also called a protein cage.

CHEMICAL METHYL GROUP.

One carbon and three hydrogen molecules that can be attached as a signal to DNA in the regulation of gene expression.

CHEMOTHERAPY.

Treatment of cancer with synthetic drugs that destroy the tumor either by inhibiting the growth of the cancerous cells or by killing the cancer cells.

CHIARI II ANOMALY.

A structural abnormality of the lower portion of the brain (cerebellum and brain stem) associated with spina bifida. The lower structures of the brain are crowded and may be forced into the foramen magnum, the opening through which the brain and spinal cord are connected.

CHOANAL ATRESIA.

A bony or membranous blockage of the passageway between the nose and pharynx at birth.

CHOLESTEROL.

A fatty-like substance that is obtained from the diet and produced by the liver. Cells require cholesterol for their normal daily functions.

CHOLINESTERASE.

Enzyme whose role is to break down released acetylcholine in the gap between nerve cells.

CHONDROCYTE.

A specialized type of cell that secretes the material which surrounds the cells in cartilage.

CHONDROSARCOMA.

A malignant tumor derived from cartilage cells.

CHOREA.

Involuntary, rapid, jerky movements.

CHOREOATHETOSIS.

Involuntary rapid, irregular, jerky movements or slow, writhing movements that flow into one another.

CHORIOCAPILLARIS.

Capillary layer of the choroid.

CHORION.

The outer membrane of the amniotic sac. Chorionic villi develop from its outer surface early in pregnancy. The villi establish a physical connection with the wall of the uterus and eventually develop into the placenta.

CHORIONIC VILLUS SAMPLING (CVS).

A procedure used for prenatal diagnosis at 10-12 weeks gestation. Under ultrasound guidance a needle is inserted either through the mother's vagina or abdominal wall and a sample of cells is collected from around the early embryo. These cells are then tested for chromosome abnormalities or other genetic diseases. Also known as chorionic villus biopsy.

CHOROID.

In the human eye, the thin layer of tissue that lies between the sclera and the retina. The choroid is rich in blood vessels that nourish the retina, and the dark pigments of the choroid absorb light rays so that they are not reflected back out of the eye.

CHOROID PLEXUS.

Specialized cells located in the ventricles of the brain that produce cerebrospinal fluid.

CHROMATID.

Each of the two strands formed by replication of a chromosome. Chromatids are held together by the centromere until the centromere divides and separates the two chromatids into a single chromosome.

CHROMOSOMAL ANEUPLODIES.

A condition in which the chromosomal number is either increased or decreased.

CHROMOSOME.

A microscopic thread-like structure found within each cell of the human body and consisting of a complex of proteins and DNA. Humans have 46 chromosomes arranged into 23 pairs. Chromosomes contain the genetic information necessary to direct the development and functioning of all cells and systems in the body. They pass on hereditary traits from parents to child (like eye color) and determine whether the child will be male or female.

CHROMOSOME DELETION.

A missing sequence of DNA or part of a chromosome.

CHROMOSOME INVERSION.

Rearrangement of a chromosome in which a section of a chromosome breaks off and rejoins the chromosome upside down.

CHROMOSOME TRANSLOCATION.

The exchange of genetic material between chromosomes, which can lead to extra or missing genetic material.

CHRONIC ATROPHIC GASTRITIS.

Irritation and break down of the stomach wall over a period of time.

CHYLOMICRON.

A type of lipoprotein made in the small intestine and used for transporting fats to other tissues in the body.

CILIARY BODY.

A structure within the eye that produces aqueous humor.

CIRCUMCISION.

The surgical removal of the fore-skin of the penis.

CIRRHOSIS.

A chronic degenerative disease of the liver in which normal cells are replaced by fibrous tissue. Cirrhosis is a major risk factor for the later development of liver cancer.

CLASS I MHC.

Major histocompatibility complex class I includes HLA-A, HLA-B, and HLA-C. These are proteins important in cellular immunity.

CLASS II MHC.

Major histocompatibility complex class II includes HLA-DP, HLA-DQ, and HLA-DR. These are proteins important in humoral immunity.

CLASS III MHC.

Major histocompatibility complex class III includes the complement system.

CLAUDICATION.

Pain in the lower legs after exercise caused by insufficient blood supply.

CLAVICLE.

Also called the collarbone. Bone that articulates with the shoulder and the breast bone.

CLEFT.

An elongated opening or slit in an organ.

CLEFT LIP.

A separation of the upper lip that is present from birth but originates early in fetal development. A cleft lip may appear on one side (unilateral) or both sides (bilateral) and is occasionally accompanied by a cleft palate. Surgery is needed to completely repair cleft lip.

CLEFT PALATE.

A congenital malformation in which there is an abnormal opening in the roof of the mouth that allows the nasal passages and the mouth to be improperly connected.

CLINICAL BREAST EXAM (CBE).

Examination of the breasts, performed by a physician or nurse.

CLINICAL TRIAL.

The testing of a drug or some other type of therapy in a specific population of patients.

CLINODACTYLY.

An abnormal inward curving of the fingers or toes.

CLITORIS.

A small mass of erectile tissue in the female genitalia.

CLONE.

A cell or organism derived through asexual (without sex) reproduction containing the identical genetic information of the parent cell or organism.

CLONUS.

A sustained series of involuntary rhythmic jerks following quick stretch of a muscle.

CLOSED-ANGLE GLAUCOMA.

An increase in the fluid pressure within the eye due to a complete, and sometimes sudden, blockage of the fluid drainage passages.

CLOVERLEAF SKULL.

An abnormal, or cloverleaf, appearance to the skull caused by premature fusion of the bones in the skull of an infant.

CLUBFOOT.

Abnormal permanent bending of the ankle and foot. Also called talipes equinovarus.

CO-DOMINANT.

Describes the state when two alleles of the same gene are both expressed when inherited together.

CO-ENZYME.

A small molecule such as a vitamin that works together with an enzyme to direct a biochemical reaction within the body.

COAGULATION.

Generally, the solidification or change from a fluid state to a semisolid mass. More specifically, the entire process of blood clotting; blood coagulation helps to close open wounds.

COAGULOPATHY.

A disorder in which blood is either too slow or too quick to coagulate (clot).

COARCTATION.

A narrowing of the aorta that is often associated with bicuspid aortic valve.

COBB ANGLE.

A measure of the curvature of scoliosis, determined by measurements made on x rays.

COCHLEA.

A bony structure shaped like a snail shell located in the inner ear. It is responsible for changing sound waves from the environment into electrical messages that the brain can understand, so people can hear.

COCHLEAR IMPLANTATION.

A surgical procedure in which a small electronic device is placed under the skin behind the ear and is attached to a wire that stimulates the inner ear, allowing people who have hearing loss to hear useful sounds.

COFACTOR.

A substance that is required by an enzyme to perform its function.

COGNITION.

The mental activities associated with thinking, learning, and memory.

COGNITIVE.

Brain functions involved in the ability to think, learn, and remember.

COGNITIVE/BEHAVIORAL THERAPIES.

Psychological counseling that focuses on changing the behavior of the patient.

COLCHICINE.

A compound that blocks the assembly of microtubules—protein fibers necessary for cell division and some kinds of cell movements, including neutrophil migration. Side effects may include diarrhea, abdominal bloating, and gas.

COLECTOMY.

Surgical removal of the colon.

COLITIS.

Inflammation of the colon.

COLLAGEN.

The main supportive protein of cartilage, connective tissue, tendon, skin, and bone.

COLOBOMA.

A birth defect in which part of the eye is absent or does not form completely.

COLON.

The large intestine.

COLONOSCOPY.

Procedure for viewing the large intestine (colon) by inserting an illuminated tube into the rectum and guiding it up the large intestine.

COLORECTAL.

Of the colon and/or rectum

COLOSTOMY.

The creation of an artificial opening into the colon through the skin for the purpose of removing bodily waste. Colostomies are usually required because key portions of the intestine have been removed.

COMPLEMENT SYSTEM.

Class III MHC (major histocompatobility complex) proteins capable of destroying invading organisms directly via natural immunity, as well as indirectly through an interaction with other components of the immune system.

COMPLETE SITUS INVERSUS.

A laterality defect resulting in a mirror image of the normal organ formation with heart, spleen, and stomach on the right, and the liver and gallbladder on the left side.

COMPOUND HETEROZYGOTE.

Having two different mutated versions of a gene.

COMPUTED TOMOGRAPHY (CT).

An imaging technique in which cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures; also called computed axial tomography.

COMT INHIBITORS.

Drugs that block catechol-O-methyltransferase, an enzyme that breaks down dopamine. COMT inhibitors include entacapone and tolcapone.

CONCEPTUS.

The products of conception, or the union of a sperm and egg cell at fertilization.

CONCORDANCE.

When two individuals have the same disease, such as when identical twins both have diabetes.

CONDUCTIVE HEARING LOSS.

Hearing loss that is the result of a dysfunction of the parts of the ear responsible for collecting sound. In this type of hearing loss, the auditory nerve is generally not damaged.

CONES.

Receptor cells that allow the perception of colors.

CONGENITAL.

Present at birth.

CONGENITAL ANOMALY.

An abnormality that is present at birth.

CONGENITAL CATARACT.

Clouding of the lens in the eye that is present at birth.

CONGENITAL HEART DISEASE.

Structural abnormality of the heart at birth. Examples include a ventricular septal defect and atrial septal defect.

CONGENITAL HYPOPLASTIC ANEMIA (CHA).

A significant reduction in the number of red blood cells present at birth, usually referring to deficient production of these cells in the bone marrow. Also sometimes called congenital aplastic anemia.

CONNECTIVE TISSUE.

A group of tissues responsible for support throughout the body; includes cartilage, bone, fat, tissue underlying skin, and tissues that support organs, blood vessels, and nerves throughout the body.

CONNEXIN.

A protein that joins cells together and allows them to exchange small substances.

CONOTRUNCAL HEART ABNORMALITY.

Congenital heart defects particularly involving the ventricular (lower chambers) outflow tracts of the heart includes subarterial ventricular septal defect, pulmonic valve atresia and stenosis, tetralogy of Fallot and truncus arteriosus.

CONSANGUINEOUS.

Sharing a common bloodline or ancestor.

CONSANGUINITY.

A mating between two people who are related to one another by blood.

CONTINENCE.

Normal function of the urinary bladder and urethra, allowing fluid flow during urination and completely stopping flow at other times.

CONTINGUOUS GENE DELETION SYNDROME.

A genetic disorder due to the deletion of a number of genes that lie close to one another on a specific chromosome.

CONTINGUOUS GENE SYNDROME.

Conditions that occur as a result of microdeletions or microduplications involving several neighboring genes.

CONTRACTURE.

A tightening of muscles that prevents normal movement of the associated limb or other body part.

CONVULSION.

Involuntary contractions of body muscles that accompany a seizure episode.

COPROLALIA.

The involuntary expression of obscene words or phrases.

COPROPRAXIA.

The involuntary display of unacceptable/obscene gestures.

CORDOCENTESIS.

A prenatal diagnostic test, usually done between 16-30 weeks of gestation. Using ultrasound guidance, a thin needle is introduced through the abdomen into the amniotic sac. A blood sample is taken directly from the umbilical cord. Tests can then be done on the blood sample.

CORNEA.

The clear, dome-shaped outer covering of the eye that lies in front of the iris and pupil. The cornea lets light into the eye.

CORNEAL TRANSPLANT.

Removal of impaired and diseased cornea and replacement with corneal tissue from a recently deceased person.

CORONAL SUTURE.

Skull suture that lies behind the forehead area, across the head from left side to the right side.

CORPORA ALBICANTIA.

Plural of corpus albicans. The scar tissue that remains on an ovarian follicle after ovulation.

CORPUS CALLOSUM.

A thick bundle of nerve fibers deep in the center of the forebrain that provides communications between the right and left cerebral hemispheres.

CORTICOSPINAL TRACT.

A tract of nerve cells that carries motor commands from the brain to the spinal cord.

CORTICOSTEROIDS.

Anti-inflammatory medications. Related to cortisol, a naturally produced hormone that controls many body functions.

COXA VARA.

A deformed hip joint in which the neck of the femur is bent downward.

CRANIAL NERVES.

The twelve nerves that originate in the brain, and control functions such as hearing, vision and facial expression.

CRANIAL SUTURE.

Any one of the seven fibrous joints between the bones of the skull.

CRANIOFACIAL.

Relating to or involving both the head and the face.

CRANIOPAGUS.

Conjoined wins with separate bodies and one shared head.

CRANIOPHARYNGIOMA.

A tumor near the pituitary gland in the craniopharyngeal canal that often results in intracranial pressure.

CRANIOSYNOSTOSIS.

A premature closure of one or more of the joints (fissures) between the bones of the skull, which causes an abnormally shaped skull.

CRANIUM.

The skeleton of the head, which include all of the bones of the head except the mandible.

CREATINE KINASE (CK).

An enzyme that is normally found in the skeletal or voluntary muscle and cardiac muscle; very high levels in the blood usually indicate breakdown of either heart or voluntary muscle.

CREATININE.

The metabolized by-product of creatine, an organic acid that assists the body in producing muscle contractions. Creatinine is found in the bloodstream and in muscle tissue. It is removed from the blood by the kidneys and excreted in the urine. Higher than normal levels of this substance may indicate kidney disease.

CREUTZFELDT-JAKOB DISEASE.

A degenerative disease of the central nervous system caused by a prion, or "slow virus."

CRI DU CHAT SYNDROME.

A syndrome caused by a deletion in chromosome 5; characterized by a strange cry that sounds like the mewing of a cat.

CRYPTOPHTHALMOS.

An abnormal formation of the eye in which the eyelid, or overlaying skin of the eye, is fused shut. Literally, "hidden eye."

CRYPTORCHIDISM.

Undescended testes, a condition in which a boy is born with one or both testicles in the lower abdomen rather than the scrotum.

CURETTAGE.

A surgical scrapping or cleaning.

CUTANEOUS.

Of, pertaining to, or affecting the skin.

CUTANEOUS SYNDACTYLY.

Fusion of the soft tissue between fingers or toes resulting in a webbed appearance.

CYANOSIS.

A bluish tinge to the skin that can occur when the blood oxygen level drops too low.

CYCLOOXYGENASE-2 (COX-2) INHIBITORS.

Anti-inflammatory drugs that work by blocking the COX-2 enzyme, which plays a role in the inflammatory process, but do not block the COX-1 enzyme, which helps protect the digestive tract.

CYDROCEPHALY.

Excessive accumulation of cerebral spinal fluid in the brain ventricles.

CYST.

An abnormal sac or closed cavity filled with liquid or semisolid matter.

CYSTIC FIBROSIS.

A respiratory disease characterized by chronic lung disease, pancreatic insufficiency and an average age of survival of 20 years. Cystic fibrosis is caused by mutations in a gene on chromosome 7 that encode a transmembrane receptor.

CYSTIC HYGROMA.

An accumulation of fluid around the head and neck caused by the blockage of drainage of lymphatic fluid.

CYSTIC HYGROMA.

An accumulation of fluid behind the fetal neck, often caused by improper drainage of the lymphatic system in utero.

CYSTIC HYGROMA.

Birth defect that appears as a soft bulging under the skin at the neck; the bulging is actually abnormal growths of sac-like structures filled with lymphatic fluid.

CYSTINE.

A sulfur-containing amino acid, sometimes found as crystals in the kidneys or urine, that forms when proteins are broken down by digestion.

CYTOKINES.

Chemicals made by the cells that act on other cells to stimulate or inhibit their function. They are important controllers of immune functions. At high levels, cytokines may be toxic to nerve cells in the developing brain.

CYTOPLASM.

The substance within a cell including the organelles and the fluid surrounding the nucleus.

CYTOSKELETON.

The network of proteins underlying and maintaining the integrity of the red blood cell membrane.

D

DANDY-WALKER MALFORMATION.

A complex structural abnormality of the brain frequently associated with hydrocephalus, or accumulation of excess fluid in the brain. Abnormalities in other areas of the body may also be present. Individuals with Dandy-Walker malformation have varying degrees of mental handicap, or none at all.

DE NOVO.

Latin term for new.

DE NOVO DELETION.

A deletion that occurs for the first time in the affected individual. The cause of de novo deletions is not known.

DE NOVO MUTATION.

Genetic mutations that are seen for the first time in the affected person, not inherited from the parents.

DEBRANCHING ENZYME.

Enzyme responsible for breaking down the branched structure of glycogen stores to release glucose into the bloodstream.

DECIDUOUS TEETH.

The first set of teeth or "baby teeth."

DECREASED PENETRANCE.

Individuals who inherit a changed disease gene but do not develop symptoms.

DEEP VEIN THROMBOSIS.

A blood clot in one of the systemic veins deep in the body.

DEFORMATION.

Abnormal shape or function in otherwise normal tissue produced by unusual mechanical forces on the embryo/fetus.

DEGENERATION.

Nerves progressively withering.

DEGENERATIVE DISC DISEASE.

Narrowing of the disc space between the spinal bones (vertebrae).

DEGENERATIVE DISORDER.

A disorder by which the body or a part of the body gradually loses its ability to fucntion.

DEGRADATION.

Loss or diminishing.

DEHYDRATION.

An extreme loss of water in the body which, if untreated, can lead to brain damage and death.

DELAYED BONE AGE.

an abnormal condition in which the apparent age of the bones, as seen in x rays, is less than the chronological age of the patient.

DELETION.

The absence of genetic material that is normally found in a chromosome. Often, the genetic material is missing due to an error in replication of an egg or sperm cell.

DELIRIUM.

A disturbance of consciousness marked by confusion, difficulty paying attention, delusions, hallucinations, or restlessness. It can be distinguished from dementia by its relatively sudden onset and variation in the severity of the symptoms.

DELUSION.

A fixed, false belief that is resistant to reason or factual disproof.

DEMENTIA.

Loss of memory and other higher functions, such as thinking or speech, lasting six months or more.

DEOXYRIBONUCLEIC ACID (DNA).

The genetic material in cells that holds the inherited instructions for growth, development, and cellular functioning.

DEPIGMENTATION.

Loss of pigment or skin color.

DEPOLARIZATION.

The dissipation of an electrical charge through a membrane. In the heart, depolarization causes the heart muscle to contract.

DEPOT DOSAGE.

A form of medication that can be stored in the patient's body tissues for several days or weeks, thus minimizing the risk of the patient forgetting daily doses.

DEPRIVATIONAL DWARFISM.

A condition where emotional disturbances are associated with growth failure and abnormalities of pituitary function.

DERMATOLOGIC.

Pertaining to the field of dermatology, the science of the skin and diseases that affect the skin.

DERMATOLOGIST.

A physician that specializes in disorders of the skin.

DERMATOSPARAXIS.

Skin fragility caused by abnormal collagen.

DERMIS.

The layer of skin beneath the epidermis.

DESCEMET'S MEMBRANE.

Sheet of tissue that lies under the stroma and protects against infection and injuries.

DESFEROXAMINE.

The primary drug used in iron chelation therapy. It aids in counteracting the life-threatening buildup of iron in the body associated with long-term blood transfusions.

DESMOID TUMOR.

Benign, firm mass of scarlike connective tissue

DESMOPRESSIN (DDAVP).

A drug used in the treatment of von Willebrand's disease.

DEUTERANOPIA.

The inability or difficulty in distinguishing red/green colors.

DEVELOPMENT.

The process whereby undifferentiated embryotic cells replicate and differentiate into limbs, organ systems, and other body components of the fetus.

DEVELOPMENTAL DELAY.

The failure of a child to meet certain developmental milestones, such as sitting, walking, and talking, at the average age. Developmental delay may indicate a problem in development of the central nervous system.

DEVELOPMENTAL MILESTONES.

Infants and toddlers develop skills at certain ages. For example, by nine months, a child should be able to grasp and toss a bottle.

DEXTROCARDIA.

Defect in which the position of the heart is the mirror image of its normal position.

DIABETES.

An inability to control the levels of sugar in the blood due to an abnormality in the production of, or response to, the hormone insulin.

DIABETES MELLITUS.

The clinical name for common diabetes. It is a chronic disease characterized by the inability of the body to produce or respond properly to insulin, a hormone required by the body to convert glucose to energy.

DIAGNOSTIC TESTING.

Testing performed to determine if someone is affected with a particular disease.

DIALYSIS.

A process of filtering and removing waste products from the bloodstream, it is used as a treatment for patients whose kidneys do not function properly. Two main types are hemodialysis and peritoneal dialysis. In hemodialysis, the blood flows out of the body into a machine that filters out the waste products and routes the cleansed blood back into the body. In peritoneal dialysis, the cleansing occurs inside the body. Dialysis fluid is injected into the peritoneal cavity and wastes are filtered through the peritoneum, the thin membrane that surrounds the abdominal organs.

DIAPHRAGMATIC HERNIA.

An abnormal opening in the diaphragm, the layer of muscle that separates the chest cavity from the abdominal cavity. The intestines are herniated through the diaphragm into the chest cavity.

DIAPHYSIS.

The middle portion, or shaft, of a long bone.

DIARRHEA.

Loose, watery stool.

DIASTOLIC BLOOD PRESSURE.

Blood pressure when the heart is resting between beats.

DICEPHALUS.

Conjoined twins who share one body but have two separate heads and necks.

DIFFERENTIATE.

Specialized development to perform a particular function.

DIGESTIVE ENZYME.

Proteins secreted by the pancreas that enter the small intestine and break down food so it can be absorbed by the body.

DIGIT.

A finger or toe.

DIHYDROTESTOSTERONE (DHT).

A male sex hormone formed from testosterone by the enzyme 5-alpha-reductase. DHT causes hair follicles to shut down, shortening the growth phase of the hair growth cycle and leading to miniaturization.

DILATED CARDIOMYOPATHY.

A diseased and weakened heart muscle that is unable to pump blood efficiently.

DIOPTER (D).

A unit of measure for describing refractive power.

DIPLEGIA.

Paralysis affecting like parts on both sides the body, such as both arms or both legs.

DIPLOID.

Means "double number." The normal number of chromosomes (two) for all cells of the human body, except for the sex cells.

DISRUPTION.

A type of anomaly formation in which a breakdown or inhibition of normal tissue development occurs.

DISTAL.

Away from the point of origin, midline, or central point.

DISTAL ARTHROGRYPOSIS.

A disorder characterized by contractions of the muscles in the hands.

DISTAL MUSCLES.

Muscles that are furthest away from the center of the body.

DISTAL MUSCULAR DYSTROPHY (DD).

A form of muscular dystrophy that usually begins in middle age or later, causing weakness in the muscles of the feet and hands.

DISULFIRAM.

A medication that has been used since the late 1940s as part of a treatment plan for alcohol abuse. Disulfiram, which is sold under the trade name Antabuse, produces changes in the body's metabolism of alcohol that cause headaches, vomiting, and other unpleasant symptoms if the patient drinks even small amounts of alcohol.

DIURETICS.

Medications that increase the excretion of urine.

DIVERTICULAE.

Sacs or pouches in the walls of a canal or organ. They do not normally occur, but may be acquired or present from birth. Plural form of diverticula.

DIZYGOTIC.

From two zygotes, as in non-identical, or fraternal twins. The zygote is the first cell formed by the union of sperm and egg.

DNA.

Deoxyribonucleic acid, inheritable material that constitutes the building blocks of life.

DNA MUTATION ANALYSIS.

A direct approach to the detection of a specific genetic mutation or mutations using one or more laboratory techniques.

DNA REPEATS.

A three letter section of DNA, called a triplet, which is normally repeated several times in a row. Too many repeats often cause the gene to not function properly, resulting in disease.

DNA TESTING.

Analysis of DNA (the genetic component of cells) in order to determine mutations in genes that may indicate a specific disorder.

DOLICOCEPHALY.

Elongated and narrow skull shape due to premature closure of the sagittal suture that runs from the forehead to the back of the skull.

DOMINANT GENE.

A gene, whose presence as a single copy, controls the expression of a trait.

DOMINANT INHERITANCE.

A type of genetic inheritance pattern results in one form of a gene being dominant over other forms. Therefore, the dominant allele can express itself and cause disease, even if only one copy is present.

DOMINANT PROGRESSIVE HEARING LOSS.

The main type of non-syndromic progressive sensorineural hearing loss seen in humans.

DOMINANT TRAIT.

A genetic trait where one copy of the gene is sufficient to yield an outward display of the trait; dominant genes mask the presence of recessive genes; dominant traits can be inherited from a single parent.

DOPAMINE RECEPTOR ANTAGONISTS (DAS).

The older class of antipsychotic medications, also called neuroleptics, which primarily block the site on nerve cells that normally receive the brain chemical dopamine.

DOPAMINE.

A neurochemical made in the brain that is involved in many brain activities, including movement and emotion.

DORSAL RHIZOTOMY.

A surgical procedure that cuts nerve roots to reduce spasticity in affected muscles.

DORSAL ROOT GANGLIA.

The subset of neuronal cells controlling impulses in and out of the brain.

DOWN SYNDROME.

A genetic condition characterized by moderate to severe mental retardation, a characteristic facial appearance, and, in some individuals, abnormalities of some internal organs. Down syndrome is always caused by an extra copy of chromosome 21, or three rather than the normal two. For this reason, Down syndrome is also known as trisomy 21.

DOWNSHOOT.

Downward movement of the eye.

DRPLA.

Dentatorubral-pallidoluysian atrophy; also called Haw River syndrome and Natito-Oyanagi disease. DRPLA is a disorder of ataxia, choreoathetosis, and dementia in adults, and ataxia, myoclonus, epilepsy, and mental retardation in children.

DRUSEN.

Fatty deposits that can accumulate underneath the retina and macula, and sometimes lead to agerelated macular degeneration (AMD). Drusen formation can disrupt the photoreceptor cells, which causes central and color vision problems for people with dry AMD.

DUCHENNE MUSCULAR DYSTROPHY (DMD).

The most severe form of muscular dystrophy, DMD usually affects young boys and causes progressive muscle weakness, usually beginning in the legs.

DUCT.

Tube-like structure that carries secretions from glands.

DUCTUS.

The blood vessel that joins the pulmonary artery and the aorta. When the ductus does not close at birth, it causes a type of congenital heart disease called patent ductus arteriosus.

DUCTUS ARTERIOSUS.

The temporary channel or blood vessel between the aorta and pulmonary artery in the fetus.

DUODENUM.

Portion of the small intestine nearest the stomach; the first of three parts of the small intestine.

DUPLICATION.

A type of chromosomal defect in which a broken segment of a chromosome attaches to the chromosome pair resulting in extra chromosomal material.

DWARFISM.

Any condition that results in extremely shortened limbs.

DYSARTHRIA.

Slurred speech.

DYSGENESIS.

Defective or abnormal formation of an organ or part usually occuring during embryonic development.

DYSKINESIA.

Impaired ability to make voluntary movements.

DYSMORPHIC.

Literally meaning misshapen, it is most often used as a general descriptive term for anomalous physical characteristics.

DYSMORPHIC FEATURE.

A change in appearance such as low set ears or a flattened nasal bridge that suggests a genetic syndrome may be present.

DYSOSTOSIS MULTIPLEX.

A variety of bone and skeletal malformations.

DYSPHORIA.

Feelings of anxiety, restlessness, and dissatisfaction.

DYSPLASIA.

Abnormal development of tissues, organs, or cells.

DYSTHYMIA.

A psychological condition of chronic depression that is not disabling, but prevents the sufferer from functioning at his or her full capacity.

DYSTONIA.

Painful involuntary muscle cramps or spasms.

DYSTOPIA CANTHORUM.

A wide spacing between the inner corners of the eyes, with the eyes themselves having normal spacing. Also called telecanthus.

DYSTROPHIN.

A protein that helps muscle tissue repair itself. Both Duchenne muscular dystrophy and Becker muscular dystrophy are caused by flaws in the gene that instructs the body how to make this protein.

DYSTROPHY.

Progressive abnormal changes in a tissue or organ.

E

E-CADHERIN/CDH1.

A gene involved in cell-to-cell connection. Alterations in this gene have been found in several families with increased rates of gastric cancer.

EAR TAGS.

Excess pieces of skin on the outside of the ear.

EARLY ON SET DYSTONIA.

Dystonia that begins in adolescence. Most common among Jews of Eastern European ancestry.

ECHOCARDIOGRAPHY.

A non-invasive technique that uses ultrasonic waves to look at the various structures and functions of the heart. The image obtained with this technique is called an echocardiogram.

ECHOLALIA.

Involuntary echoing of the last word, phrase, or sentence spoken by someone else.

ECHOPRAXIA.

The imitation of the movement of another individual.

ECTODERM.

The outermost of the three embryonic cell layers, which later gives rise to the skin, hair, teeth, and nails. These are cells affected in Ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome.

ECTODERMAL DYSPLASIA.

A hereditary condition that results in the malformation of the skin, teeth, and hair. It is often associated with malfunctioning or absent sweat glands and/or tear ducts.

ECTOPIA LENTIS.

Dislocation of the lens of the eye. It is one of the most important single indicators in diagnosing Marfan syndrome.

ECTOPIC.

Tissue found in an abnormal location.

ECTRODACTYLY.

A birth defect involving a split or cleft appearance of the hands or feet, also referred to as a "lobster-claw malformation."

ECZEMA.

Inflammation of the skin with redness and other variable signs such as crusts, watery discharge, itching.

EDEMA.

Extreme amount of watery fluid that causes swelling of the affected tissue.

EDWARDS SYNDROME.

A syndrome caused by trisomy 18; characterized by multi-system defects; and usually lethal by age 1.

EFFLUVIUM.

The medical term for massive hair loss or shedding.

ELASTIC FIBER.

Fibrous, stretchable connective tissue made primarily from proteins, elastin, collagen, and fibrillin.

ELASTIN.

A protein that gives skin the ability to stretch and then return to normal.

ELECTROCARDIOGRAM (ECG, EKG).

A test used to measure electrical impulses coming from the heart in order to gain information about its structure or function.

ELECTROCONVULSIVE THERAPY.

A psychological treatment in which a series of controlled electrical impulses are delivered to the brain in order to induce a seizure within the brain.

ELECTROLYTE.

A solution or a substance in a solution consisting of various chemicals that can carry electric charges. They exist in the blood as acids, bases, and salts, such as sodium, calcium, potassium, chlorine, and magnesium.

ELECTROMYOGRAPHY (EMG).

A diagnostic test that records the electrical activity of muscles. In the test, small electrodes are placed on or in the skin; the patterns of electrical activity are projected on a screen or over a loudspeaker. This procedure is used to test for muscle disorders, including muscular dystrophy.

ELECTRORETINOGRAPHY (ERG).

A diagnostic test that records electrical impulses created by the retina when light strikes it.

EMBOLIZATION THERAPY.

Introduction of various substances into the circulation to plug up blood vessels in order to stop bleeding.

EMBRYO.

The earliest stage of development of a human infant, usually used to refer to the first eight weeks of pregnancy. The term fetus is used from roughly the third month of pregnancy until delivery.

EMBRYOGENESIS.

The formation and growth of the embryo.

EMOLLIENT.

Petroleum or lanolin based skin lubricants.

EMPHYSEMA.

A chronic lung disease that begins with breathlessness during exertion and progresses to shortness of breath at all times, caused by destructive changes in the lungs.

ENCAPSULATED.

Referring to bacteria that have a thick capsule protecting their cell wall.

ENCEPHALOCELE.

A gap in the skull through which membranes and brain tissue may protrude.

ENCEPHALOPATHY.

A degenerative disease of the brain that has a sudden onset.

ENCHONDROMAS.

Benign cartilaginous tumors arising in the cavity of bone. They have the possibility of causing lytic destruction within the bone.

ENDOCARDITIS.

A dangerous infection of the heart valves caused by certain bacteria.

ENDOCRINE SYSTEM.

A system of ductless glands that regulate and secrete hormones directly into the bloodstream.

ENDOLYMPH.

The fluid in the inner ear.

ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY (ERCP).

A method of viewing the pancreas by inserting a thin tube down the throat into the pancreatic and bile ducts, injection of dye, and performing x rays.

ENDOSCOPY.

A slender, tubular optical instrument used as a viewing system for examining an inner part of the body and, with an attached instrument, for biopsy or surgery.

ENDOSTEAL.

Relating to the endosteum, which is the lining of the medullary cavity.

ENDOTHELIAL CELLS.

The cells lining the inner walls of the blood vessels.

ENDOTHELIUM.

Extremely thin innermost layer of the cornea.

ENLARGED VESTIBULAR AQUEDUCT (EVA).

An enlargement of a structure inside the inner ear called the vestibular aqueduct, which is a narrow canal that allows fluid to move within the inner ear. EVA is seen in approximately 10% of people who have sensorineural hearing loss.

ENTEROCOLITIS.

Severe inflammation of the intestines that affects the intestinal lining, muscle, nerves and blood vessels.

ENTEROSCOPY.

A procedure used to examine the small intestine.

ENTEROVIRUS.

Any of a group of viruses that primarily affect the gastrointestinal tract.

ENTHESITIS.

Inflammation at the place where the ligaments insert into the bone.

ENTHESOPATHY.

Disorder of the ligament attachment to the bone.

ENZYMATIC/ENZYME REPLACEMENT THERAPY.

A treatment method used to replace missing enzymes. It is possible to synthesize enzymes and then inject them intravenously into patients.

ENZYME.

A protein that catalyzes a biochemical reaction or change without changing its own structure or function.

ENZYME EFFICIENCY.

The rate at which an enzyme can perform the chemical transformation it is expected to accomplish. This is also called turnover rate.

EPENDYMOMA.

Tumor of the central nervous system derived from cells that line the central canal of the spinal cord and the ventricles of the brain.

EPIBULBAR DERMOIDS.

Cysts on the eyeball.

EPICANTHAL FOLD.

Fold of skin extending from the eyelid over the inner corner of the eye.

EPIDERMIS.

The outermost layer of the skin.

EPIDERMOID CYST.

Benign, cystic tumor derived from epithelial cells.

EPIDIDYMUS.

Coiled tubules that are the site of sperm storage and maturation for motility and fertility. The epididymis connects the testis to the vas deferens.

EPIGENETIC.

Implying a modification outside of actual mutation of the DNA sequence, such as the addition of a methyl group.

EPILEPSY.

A neurological disorder characterized by recurrent seizures with or without a loss of consciousness.

EPIPHYSIS.

The end of a long bone, usually terminating in a joint.

EPITHELIAL CELLS.

The layer of cells that cover the open surfaces of the body such as the skin and mucous membranes.

EPITHELIUM.

The layer of cells that cover the open surfaces of the body such as the skin and mucous membranes.

ERYTHEMA.

Redness of the skin due to dilatation of capillaries.

ERYTHEMA NODOSUM LEPROSUM.

A complication of leprosy characterized by development of painful small swellings due to inflammation of a blood or lymph vessel. It is often accompanied by inflammation of a nerve or nerves, causing decreased function of the affected area.

ERYTHROPOIESIS.

The process through which new red blood cells are created; it begins in the bone marrow.

ERYTHROPOIETIC.

Referring to the creation of new red blood cells.

ESOPHAGUS.

The part of the digestive tract which connects the mouth and stomach; the foodpipe.

ESTROGEN.

A female sex hormone.

ETHANOL.

The chemical name for beverage alcohol. It is also sometimes called ethyl alcohol or grain alcohol to distinguish it from isopropyl or rubbing alcohol.

ETIOLOGY.

The cause of a disease, syndrome, or anomaly.

EUGENICS.

A social movement in which the population of a society, country, or the world is to be improved by controlling the passing on of hereditary information through mating.

EVOKED RESPONSE TESTS.

Tests that measure the speed of brain connections.

EXCISION.

Surgical removal.

EXOCRINE PANCREAS.

The secreting part of the pancreas.

EXOMPHALOS.

An umbilical protrusion or hernia.

EXON.

The expressed portion of a gene. The exons of genes are those portions that actually chemically code for the protein or polypeptide that the gene is responsible for producing.

EXOSTOSIS.

An abnormal growth (benign tumor) on a bone.

EXPANSION.

A genetic abnormality caused by a sequence of nucleotides that is repeated too many times in a section of a gene.

EXTERNAL MEATUS.

The external opening through which urine and seminal fluid (in males only) leave the body.

EXTRAOCULAR MUSCLE FIBROSIS.

Abnormalities in the muscles that control eye movement.

EXTRAPYRAMIDAL SYMPTOMS (EPS).

A group of side effects associated with antipsychotic medications. EPS include parkinsonism, akathisia, dystonia, and tardive dyskinesia.

EXUDATE.

Fluid that accumulates and penetrates the walls of vessels, leaking into the surrounding tissue.

F

FACIAL ASYMMETRY.

Term used to describe when one side of the face appears different than the other.

FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY (FSH).

This form of muscular dystrophy, also known as Landouzy-Dejerine condition, begins in late childhood to early adulthood and affects both men and women, causing weakness in the muscles of the face, shoulders, and upper arms.

FACTOR VIII.

A protein involved in blood clotting that requires vWF for stability and long-term survival in the bloodstream.

FACTORS.

Coagulation factors are substances in the blood, such as proteins and minerals, that are necessary for clotting. Each clotting substance is designated with roman numerals I through XIII.

FAILURE TO THRIVE.

Significantly reduced or delayed physical growth.

FALLOPIAN TUBE.

Either of a pair of tubes that conduct ova from the ovaries to the uterus.

FAMILIAL.

A trait observed with higher frequency than would be expected by chance within the same family, whether the origin is genetic, environmental, or a combination of both.

FAMILIAL ADENOMATOUS POLYPOSIS (FAP).

Inherited syndrome causing large numbers of polyps and increased risk of colon cancer and other cancers.

FAMILIAL GASTRIC CANCER.

Gastric cancer that occurs at a higher rate in some families.

FANCONI SYNDROME.

A reabsorbtion disorder in the kidney tubules.

FASCICULATIONS.

Involuntary twitching of patient's muscles.

FATTY ACIDS.

The primary component of fats (lipids) in the body. Carnitine palmitoyl transferase (CPT) deficiency involves abnormal metabolism of the longchain variety of fatty acids.

FECAL (OCCULT) BLOOD TEST.

Study of stool (feces) to identify loss of blood in the gastrointestinal system.

FETAL ALCOHOL SYNDROME.

Syndrome characterized by distinct facial features and varying mental retardation in an infant due to impaired brain development resulting from the consumption of alcohol during pregnancy.

FETAL HYDROPS.

A condition in which there is too much fluid in the fetal tissues and/or cavities.

FETOSCOPY.

A technique by which a developing fetus can be viewed directly using a thin, flexible optical device (fetoscope) inserted into the mother's uterus.

FETUS.

The term used to describe a developing human infant from approximately the third month of pregnancy until delivery. The term embryo is used prior to the third month.

FETUS IN FETU.

One fetus growing inside the body of its twin.

FIBRILLATION.

A rapid, irregular heartbeat.

FIBRILLIN.

A protein that is an important part of the structure of the body's connective tissue. In Marfan's syndrome, the gene responsible for fibrillin has mutated, causing the body to produce a defective protein.

FIBRILLIN-2.

A protein that forms part of the body's connective tissue. The precise function of fibrillin-2 is not known.

FIBRIN.

The final substance created through the clotting cascade, which provides a strong, reliable plug to prevent further bleeding from the initial injury.

FIBRINOGEN.

A fibrous protein that circulates in blood and participates in blood clotting by attaching to platelets.

FIBROBLAST.

Cells that form connective tissue fibers like skin.

FIBROBLAST GROWTH FACTOR RECEPTOR GENE.

A type of gene that codes for a cell membrane receptor involved in normal bone growth and development.

FIBROID/FIBROMA.

A non-cancerous tumor of connective tissue made of elongated, threadlike structures, or fibers, which usually grow slowly and are contained within an irregular shape. Fibroids are firm in consistency but may become painful if they start to break down or apply pressure to areas within the body. They frequently occur in the uterus and are generally left alone unless growing rapidly or causing other problems. Surgery is needed to remove fibroids.

FIBROSIS.

The abnormal development of fibrous tissue; scarring.

FINASTERIDE.

An oral medication used to treat male pattern hair loss. Finasteride, sold under the trade names Proscar and Propecia, is an androgen inhibitor.

FINE NEEDLE ASPIRATION (FNA).

Insertion of a thin needle through the skin to an area of sample tissue.

FIRST-DEGREE RELATIVE.

A parent, child or sibling is a first degree relative. First-degree relatives have one half of their genes in common.

FIRST-RANK SYMPTOMS.

A set of symptoms designated by Kurt Schneider in 1959 as the most important diagnostic indicators of schizophrenia. These symptoms include delusions, hallucinations, thought insertion or removal, and thought broadcasting. First-rank symptoms are sometimes referred to as Schneiderian symptoms.

FISH (FLUORESCENCE IN SITU HYBRIDIZATION).

Technique used to detect small deletions or rearrangements in chromosomes by attempting to attach a fluorescent (glowing) piece of a chromosome to a sample of cells obtained from a patient.

FISTULA.

An abnormal passage or communication between two different organs or surfaces.

FLEXION.

The act of bending or condition of being bent.

FLEXION CREASES.

The lines present on the palms of the hands and the soles of the feet from normal bending of these body parts. Some individuals affected with arthrogryposis lack these characteristic lines.

FLUORESCEIN ANGIOGRAPHY.

Procedure to look at the blood vessel system of the eye. Fluorescein, a dye, is injected and photographs are taken as the dye passes through the eye's blood vessels.

FLUOROCHROME.

A fluorescent compound used for visualization in FISH.

FMR-1 GENE.

A gene found on the X chromosome. Its exact purpose is unknown, but it is suspected that the gene plays a role in brain development.

FOCAL SEIZURE.

A seizure that causes a brief and temporary change in movement, sensation, or nerve function.

FOLATE-SENSITIVE FRAGILE SITE.

A chromosome location which, under folate-deficient conditions, appears as a gap in the chromosome and is susceptible to breakage.

FOLLICLE.

A pouch-like depression.

FOLLICLE-STIMULATING HORMONE (FSH).

A hormone that in females stimulates estrogen and in males stimulates sperm production.

FONTANELLE.

One of several "soft spots" on the skull where the developing bones of the skull have yet to fuse.

FORAMEN.

A small opening or hole in a body part or tissue. Dandy-Walker malformation is characterized by the absence or failure to develop the three foramina in the fourth ventricle of the brain.

FOREBRAIN.

The anterior of the front section of the brain.

FOUNDER EFFECT.

increased frequency of a gene mutation in a population that was founded by a small ancestral group of people, at least one of whom was a carrier of the gene mutation.

FRAGILE X SYNDROME.

A condition caused by an abnormality of a region on the X chromosome which may be expressed in males or females, and may increase in severity when inherited from the mother.

FRONTAL BOSSING.

A term used to describe a rounded forehead with a receded hairline.

FRONTAL PLAGIOCEPHALY.

An abnormal condition of the skull in which the front is more developed on one side than it is on the other side.

FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI).

A form of imaging of the brain that registers blood flow to functioning areas of the brain.

FUNDUS.

The interior back wall of the eyeball.

G

G-TUBE.

A gastrostomy tube, which is inserted surgically into the stomach and used for feeding and for administering medications.

GAIT.

A manner of walking.

GAIT DISTURBANCES.

Disturbances that affect the manner of walking.

GALACTITOL.

An alcohol derivative of galactose that builds up in the lens and causes cataracts.

GALACTOSE.

One of the two simple sugars, together with glucose, that makes up the protein, lactose, found in milk. Galactose can be toxic in high levels.

GALACTOSEMIA.

Abnormally high levels of galactose in the blood due to an inherited defect in the conversion of galactose to glucose.

GALACTOSURIA.

High levels of galactose found in the urine that is seen with galactosemia.

GALLBLADDER.

A small, pear-shaped organ in the upper right hand corner of the abdomen. It is connected by a series of ducts (tube-like channels) to the liver, pancreas, and duodenum (first part of the small intestine). The gallbladder receives bile from the liver, and concentrates and stores it. After a meal, bile is squeezed out of the gallbladder into the intestine, where it aids in digestion of food.

GAMETE.

A reproductive cell; an ovum or sperm

GAMMA AMINO BUTYRIC ACID (GABA).

An amino acid that functions as the major inhibitory neurotransmitter in the nervous system.

GAMMA KNIFE.

Equipment that precisely delivers a concentrated dose of radiation to a predetermined target using gamma rays.

GANGLIONEUROBLASTOMA.

A tumor of the nerve fibers and ganglion cells.

GANGLIOSIDE.

A fatty (lipid) substance found within the brain and nerve cells.

GANGRENE.

Decay or death of body tissue because the blood supply is cut off. Tissues that have died in this way must be surgically removed.

GASTRIC.

Associated with the stomach.

GASTRIC TUBE.

A tube that is surgically placed though the skin of the abdomen to the stomach so that feeding with nutritional liquid mixtures can be accomplished.

GASTROENTEROLOGIST.

A physician who specializes in disorders of the digestive system.

GASTROESPHAGEAL REFLUX.

The return of the contents of the stomach back up into the esophagus.

GASTROINTESTINAL.

Pertaining to the digestive organs and structures, including the stomach and intestines.

GASTROINTESTINAL (GI) SYSTEM.

The body system involved in digestion, the breaking down and use of food. It includes the stomach, small intestine, and large intestine. Also known as the gastrointestinal tract.

GASTROSCHISIS.

A small defect in the abdominal wall normally located to the right of the umbilicus, and not covered by a membrane, where intestines and other organs may protrude.

GASTROSTOMY.

The construction of an artificial opening from the stomach through the abdominal wall to permit the intake of food.

GAUCHER DISEASE.

Autosomal recessive metabolic disorder caused by dysfunction of the lysosomal enzyme beta-glucosidase.

GAVAGE.

Feeding tube.

GENE.

A building block of inheritance, which contains the instructions for the production of a particular protein, and is made up of a molecular sequence found on a section of DNA. Each gene is found on a precise location on a chromosome.

GENE MUTATION.

A permanent change in genetic material that is transmittable.

GENE THERAPY.

Replacing a defective gene with the normal copy.

GENE TRANSCRIPTION.

The process by which genetic information is copied from DNA to RNA, resulting in a specific protein formation.

GENETIC.

Referring to genes and characteristics inherited from parents.

GENETIC ANTICIPATION.

The tendency for an inherited disease to become more severe in successive generations.

GENETIC COUNSELOR.

A health professional with advanced training in genetics and psychology who educates people about genetic conditions and testing.

GENETIC DISEASE.

A disease that is (partly or completely) the resul