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Gale Encyclopedia of Genetic Disorder / Gale Encyclopedia of Genetic Disorders, Two Volume Set - Volume 2 - M-Z - I

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Cirrhosis is a major risk factor for the later development of liver cancer.

CLASS I MHC Includes HLA-A, HLA-B, and HLA-C. Important in cellular immunity.

CLASS II MHC HLA-DP, HLA-DQ, and HLA-DR. Important in humoral immunity.

CLASS III MHC 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.

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

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.

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 The process by which a liquid becomes a solid, as in blood clotting.

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/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 disorder 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.

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COMPOUND HETEROZYGOTE Having two different mutated versions of a gene.

COMPUTED TOMOGRAPHY (CT) SCAN An imaging procedure that produces a three-dimensional picture of organs or structures inside the body, such as the brain.

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 Refers to a disorder 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 disorders primarily 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 transparent structure of the eye over the lens that is continous with the sclera in forming the outermost, protective, layer of 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 bundle of long nerve fibers that runs from the motor control region of the cerebral cortex to the spinal cord, where it connects to nerves that control movement in the legs.

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.

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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 twins 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 Premature, delayed, or otherwise abnormal closure of the sutures of the skull.

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

CREATININE A waste product of the body found in the urine. It is useful in determining the overall kidney function.

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 A condition in which one or both testes fail to descend normally.

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/CYANOTIC The bluish color of the skin that occurs when there is very low oxygen in the blood that is being transported throughout the body.

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

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

CYTOKINE A protein associated with inflammation that, at high levels, may be toxic to nerve cells in the developing brain.

CYTOKINES Proteins released by helper T-cells that stimulate and support immune responses (inflammation) mediated by B-cells and killer T-cells. 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.

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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.

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.

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.

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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 A condition of deteriorated mental ability characterized by a marked decline of intellect and often by emotional apathy.

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

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

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.

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. Haloperidol and fluphenazine can be given in depot form.

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

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-threat- ening buildup of iron in the body associated with longterm blood transfusions.

DESMOID TUMOR Benign, firm mass of scar-like connective tissue

DESMOPRESSIN (DDAVP) A drug used in the treatment of von Willebrand 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 When children do not reach certain milestones at appropriate ages. For example, a child should be able to speak by the time he or she is five years old.

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 Disorder 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 inadequate production or use of insulin.

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

DIALYSIS Process by which special equipment purifies the blood of a patient whose kidneys have failed.

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. Plural–digits.

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.

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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.

DISTAL Away from the point of origin.

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 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 changes in genes that may indicate a specific disorder.

DOMINANT A trait that is expressed equally in homozygous, heterozygous, and hemizygous individuals.

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

DOMINANT INHERITANCE A type of genetic inheritance pattern that 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 A neurochemical made in the brain that is involved in many brain activities, including movement and emotion.

DOPAMINE RECEPTOR ANTAGONISTS (DAS) The older class of antipsychotic medications, also called neuroleptics. These primarily block the site on nerve cells that normally receive the brain chemical dopamine.

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.

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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 chromosomal abnormality 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 Abnormal formation of an organ or part usually occuring during embryonic development.

DYSKINESIA Impaired ability to make voluntary movements.

DYSMORPHIC FEATURE A subtle 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/DYSPLASTIC The abnormal growth or development of a tissue or organ.

DYSTHYMIA A psychological condition of chronic depression that is not disabling, but prevents the patient 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.

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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.

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.

ECHOCARDIOGRAM A non-invasive technique, using ultrasonic waves, used to look at the various structures and function of the heart.

ECHOCARDIOGRAPH A record of the internal structures of the heart obtained from beams of ultrasonic waves directed through the wall of the chest.

ECHOLALIA Involuntary echoing of the last word, phrase, or sentence spoken by someone else or sound in the environment.

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.

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 and/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, and 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 disorders; and usually lethal by age one.

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.

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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 test that uses electrodes to record the electrical activity of muscle. The information gathered is used to diagnose neuromuscular disorders.

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.

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.

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.

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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.

EPILEPSY A seizure disorder.

EPIPHYSES The growth area at the end of a bone.

EPIPHYSIS The end of long bones, 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.

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.

EXCISION Surgical removal.

EXOCRINE PANCREAS The secreting part of the pancreas.

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.

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.

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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 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 a patient’s muscles.

FATTY ACIDS The primary component of fats (lipids) in the body. Carnitine palmitoyl transferase (CPT) deficiency involves abnormal metabolism of the long-chain 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 develop-

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ment 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 In this case, one fetus grows inside the body of the other twin.

FIBRILLATION A rapid, irregular heartbeat.

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.

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.

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.

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

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.

I G

GAIT A 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 disorder 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.

GANGLIONEUROBLASTOMA A tumor of the nerve fibers and ganglion cells.

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

GANGRENE Death of a tissue, usually caused by insufficient blood supply and followed by bacterial infection of the tissue.

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 Concerning the stomach and intestine.

GASTROINTESTINAL (GI) SYSTEM Body system involved in digestion, the breaking down and use of food.

GASTROSCHISIS A small abnormality 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 THERAPY Replacing an abnormal 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 result of the abnormal function or expression of a gene; a disease caused by the inheritance and expression of a genetic mutation.

GENETIC ENGINEERING The manipulation of genetic material to produce specific results in an organism.

GENETIC HETEROGENEITY The occurrence of the same or similar disease, caused by different genes among different families.

GENETIC SUSCEPTIBILITY The predisposition to a disease resulting from one or more genetic traits.

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