Genetic and Medical Glossary

the abbreviation for cytosine, a pyrimidine nitrogenous base found in the structure of both DNA and RNA

any of the medium brown spots usually found on the trunk, pelvis, and creases of the elbow

syndrome featuring angulation of the long bones such as femur and tibiae

inability of the DIP joints and/or PIP joints of the fingers to be extended 180° by either active or passive means

a gene suspected of causing a specific disease

chronic disease of the heart muscle

a healthy individual who has one normal allele and one defective allele for a recessive genetic disease

specialized testing to see whether an individual carries a mutated gene for a specific condition

testing of an individual who is at risk due to a family history to determine if he or she is a carrier of a mutated or faulty gene for a particular genetic condition

chromosomal disorder in which the short arm and a small region of the long arm of chromosome 22 are duplicated four times; characterized by distinctive eye (ocular) abnormality that is sometimes present whereby there is partial absence of ocular tissue (coloboma), often affecting both eyes (bilateral); other symptoms include mild growth delays before birth, mild intellectual impairment, malformations of the skull and facial (craniofacial) region, the heart, the kidneys, and/or anal region; down-slanting eyelid folds (palpebral fissures), widely spaced eyes (ocular hypertelorism), misshapen ears with abnormal outgrowths of skin and small depressions in front of the outer ears (preauricular tags and pits), and/or absence (atresia) of the anal canal, with an abnormal passage (fistula) from the end portion of the large intestine (rectum) into abnormal locations

at or near the tail or the posterior part of the body

obsolete, nonspecific term for a craniofacial malformation that has morphologic features of a monkey

constricted part (central region of the chromosome that separates it into its two arms (the p arm and q arm)

structure of the brain located in the medial, cortico-nuclear zone of the cerebellum

part of the brain at the back of the skull whose function is to coordinate and regulate muscular activity

surface layer of gray tissue of the cerebrum, frequently called the gray matter

abnormal brain development in which the brain did not fully develop, grew abnormally, experienced incomplete division, or developed with incomplete organization

slowly progressive demyelinating peripheral neuropathy characterized by distal muscle weakness and atrophy, sensory loss, and slow nerve conduction velocity; often associated with pes cavus foot deformity and bilateral foot drop; caused by duplication of PMP22 located on chromosome 17 at 17p12

multisystem disorder caused by mutation or deletion of the CHD7 gene located at 8q12 on chromosome 8 and characterized by the presence of colobomas and cranial nerve defects (C) heart defects, especially tetralogy of Fallot (H), atresia of the choanae (blocked nasal breathing passages (A), retardation of growth and development (R), genital underdevelopment (G), and ear abnormalities and sensori-neural hearing loss (E)

reduction in size of the zygomatic process of the temporal bone of the skull, which forms the middle and lateral inferior orbital margin; flat cheekbone, zygomatic underdevelopment

occurs when part of the cerebellum is located below the foramen magnum; may develop when the bony space is smaller than normal, causing the cerebellum and brain stem to be pushed downward into the foramen magnum and into the upper spinal cana

narrowing or blockage of the nasal airway by tissue

disorder of cartilage and bone development that occurs almost exclusively in males; abnormality that appears on x-rays as spots (stippling) near the ends of bones and in cartilage)

noninflammatory abnormality of the choroid with extension to the retina

a procedure in which fetal cells are obtained from an embryonic structure called the chorion and analyzed for the presence of genetic abnormalities in the fetus

a thin vascular layer between the sclera and the retina of the eye; supplies blood to the retina and conducts arteries and nerves to other eye structures

either of two threadlike strands into which a chromosome divides longitudinally during cell division; each contains a double helix of DNA

the material of which the chromosomes of organisms other than bacteria (i.e., eukaryotes) are composed. It consists of protein, RNA, and DNA

type of chromosome abnormality involving a change in the structure of the native chromosome and encompass several different classes of events: deletions, duplications, inversions; and translocations

the form in which genetic material is found in the nucleus of a cell; composed of a single DNA molecule that is extremely tightly coiled and usually visible only during the processes of mitosis and meiosis

locations on a chromosome where DNA might get deleted, inverted, or swapped around

a diagram showing the locations of genes on a particular chromosome; generated through analysis of linkage experiments involving those genes

a change in chromosome structure caused by chromosome breakage followed by improper rejoining (eg, deletions, insertions, inversions, and translocations)

process or act of exchanges of genes between chromosomes, resulting in a different genetic combination and ultimately to the formation of unique gametes with chromosomes that are different from those in parents

fissure in the upper lip that is due to failure of the left and right sides of the fetal lip tissue to fuse; correctable by surgery

condition that primarily affects the development of the bones and teeth, resulting in underdeveloped or absent collarbones, delayed closing of the spaces between the bones of the skull, decreased bone density, delayed loss of the primary and delayed appearance of the secondary teeth, unusually shaped, peg-like teeth and misalignment of the teeth and jaws (malocclusion)

an experimental research study used to determine the safety and effectiveness of a medical treatment or drug

a molecule, cell, or organism that is an exact genetic copy of another

a DNA molecule that can be used to transport genes of interest into cells, where these genes can then be copied

trilobar skull configuration when viewed from the front or behind

congenital deformity of the ankles and/or feet in which the foot is turned inward and downward (talipes equinovarus), is angled at the heel with the toes pointing upward and outward (calcaneal valgus), or the front of the foot is turned inward (metatarsus varus)

broadening of the soft tissues of the digital tips in all dimensions associated with an increased longitudinal and lateral curvature of the nails

bend or curvature of the fifth fingers (“pinkies") toward the adjacent fourth fingers

congenital constriction (narrowing) of the aorta that impedes the flow of blood below the level of the constriction and increases blood pressure

inherited form of dwarfism caused by a defect in one of the genes involved in the normal repair of DNA (ERCC8 gene for CS-type I mapped to chromosome 5 and ERCC6 gene for CS-type mapped to chromosome 10 at locus 10q11); diagnosed by the presence of three signs: growth retardation (short stature), abnormal sensitivity to light (photosensitivity), and prematurely aged appearance (progeria)

portion of a gene's DNA or RNA (exons) that codes for protein. The region is bounded nearer the 5' end by a start codon and nearer the 3' end with a stop codon

a group of three nucleotides in messenger RNA (mRNA) that represent a single amino acid in the genetic code

hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc

technology wherein a DNA test sample is competitively hybridized with a reference sample of DNA of known sequence to a DNA microarray, used to detect copy number changes in the test sample

hydrogen bond formation in DNA and RNA that occurs only between cytosine and guanine (in both DNA and RNA) or between adenine and thymine (in DNA) or adenine and uracil (in RNA)

mosaicism that is seen only in the placenta but not in the fetus

present at birth, not necessarily inherited

a defect or disorder that occurs during prenatal development

general term for truncus arteriosus, transposition of the great arteries, double outlet of the right ventricle, and tetralogy of Fallot; in truncus arteriosus there is a single outflow tract instead of a separate aorta and pulmonary artery

of the same blood or origin; in genetics, the term implies the sharing of genetic traits or characteristics from the same ancestors (eg, cousins)

A map that shows regions on a chromosome where neighboring portions of DNA overlap; the map provides information about a large segment of a genome by looking at a series of overlapping clones

shortening and hardening of muscles, tendons, or other tissue, often leading to deformity and rigidity of joints

structural chromosomal aberrations - duplications or deletions of relatively small areas of DNA. CNV are present in virtually all individuals. Most CNV do not cause any hereditary disorders but may affect a person's susceptibility to non-hereditary diseases or influence a person's response to some environmental factors

congenital heart defect in which there is a small extra chamber which results in slowing of the passage of blood from the lungs into the heart (left atrium and ventricle) due to the pulmonary veins (returning blood from the lungs) draining into this extra "third atrium"

pupil of the eye is off-center

inherited as an autosomal dominant condition involving the NIPBL gene on chromosome 5 or as an X-linked condition involving the SMC1L1 gene on the X chromosome; characterized by delays in physical development before and after birth, characteristic abnormalities of the head and facial (craniofacial) area, malformations of the hands and arms (upper limbs); and mild to severe intellectual impairment; other symptoms include an unusually small, short head (microbrachycephaly), an abnormally long vertical groove between the upper lip and nose (philtrum), a depressed nasal bridge, upturned nostrils (anteverted nares) and a protruding upper jaw (maxillary prognathism)

genetic disorder characterized by spinal column abnormalities, dwarfism and a swollen abdomen; also called Jarcho-Levin syndrome

disorder characterized by multiple noncancerous, tumor-like growths called hamartomas and an increased risk of developing certain cancers

broadening of the head and neck of the femur

relating to the cranium and the face

a congenital defect involving the skull bones of a newborn, whereby the bones are fused together at birth and require surgical intervention to allow for normal brain development

also called 5p minus syndrome or “Cat Cry” or syndrome due to the cat-like cry typical of newborns; chromosomal disorder in which a variable portion of the short arm of chromosome 5 is missing or deleted; most deletions are de nova or sporadic; common symptoms include a distinctive cry that resembles a cat’s mewing sound, characteristic facial features, slow growth, and microcephaly; affected children also exhibit delays in the acquisition of skills requiring the coordination of muscular and mental activities (psychomotor disability) and moderate to severe intellectual disability

specific portion of a chromosome or a gene that, when altered in some way (deleted, duplicated, or otherwise mutated), produces a characteristic set of phenotypic abnormalities associated with a particular syndrome or disorder

absent palpebral fissures, with skin passing continuously from the forehead or eyebrow onto the cheek, often with the presence of a tuft of hair; typically associated with a rudimentary or small globe (hidden eye)

absence of one or both testes from the scrotum

computerized tomography that combines a series of X-ray views taken from many different angles with computer processing to create cross-sectional images of the bones and soft tissues

relating to, or affecting the skin

pink marble-like mottling of the skin caused by exposure to cold temperature or associated with various debilitating diseases

congenital defect characterized by fusion of the orbits into a single cavity containing one eye

one of three principal openings in the subarachnoid space between the arachnoid and pia mater layers of the meninges surrounding the brain

abnormal tissue development in the kidney that can be confined to a small portion of one (unilateral or both (bilateral) kidneys arranged in a specific pattern within the kidney or randomly present throughout one or both kidneys

the study of chromosome number and structure, including identification of abnormalities

a pyrimidine nitrogenous base found in the structure of both DNA and RNA