A chromosomal abnormality consisting of the presence of a third copy of chromosome 21 in somatic cells.
A chromosomal dysgenesis syndrome resulting from a triplication or translocation of chromosome 21. Down syndrome occurs in approximately 1:700 live births. Abnormalities are variable from individual to individual and may include mental retardation, retarded growth, flat hypoplastic face with short nose, prominent epicanthic skin folds, small low-set ears with prominent antihelix, fissured and thickened tongue, laxness of joint ligaments, pelvic dysplasia, broad hands and feet, stubby fingers, transverse palmar crease, lenticular opacities and heart disease. Patients with down syndrome have an estimated 10 to 30-fold increased risk for leukemia; most have symptoms of alzheimer's disease by age 40. Also known as trisomy 21 syndrome.
A chromosome disorder associated either with an extra chromosome 21 or an effective trisomy for chromosome 21. Clinical manifestations include hypotonia, short stature, brachycephaly, upslanting palpebral fissures, epicanthus, brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, simian crease, and moderate to severe intellectual disability. Cardiac and gastrointestinal malformations, a marked increase in the incidence of leukemia, and the early onset of alzheimer disease are also associated with this condition. Pathologic features include the development of neurofibrillary tangles in neurons and the deposition of amyloid beta-protein, similar to the pathology of alzheimer disease. (menkes, textbook of child neurology, 5th ed, p213)
A disorder caused by the presence of an extra chromosome 21 and characterized by mental retardation and distinguishing physical features.
A disorder that results from a chromosomal abnormality.
Chromosome disorder associated either with an extra chromosome 21 or an effective trisomy for chromosome 21; clinical manifestations include hypotonia, short stature, brachycephaly, upslanting palpebral fissures, epicanthus, brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, simian crease, and moderate to severe mental retardation.
Clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material (either a whole chromosome or a chromosome segment). (from thompson et al., genetics in medicine, 5th ed, p429)
Clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material, either a whole chromosome or a chromosome segment.
Down syndrome is set of mental and physical symptoms that result from having an extra copy of chromosome 21. Even though people with down syndrome may have some physical and mental features in common, symptoms of down syndrome can range from mild to severe. Usually, mental development and physical development are slower in people with down syndrome than in those without it.people with the syndrome may also have other health problems. They may be born with heart disease. They may have dementia. They may have hearing problems and problems with the intestines, eyes, thyroid and skeleton.the chance of having a baby with down syndrome increases as a woman gets older. Down syndrome cannot be cured. However, many people with down syndrome live productive lives well into adulthood. nih: national institute of child health and human development
The most frequently occurring mental retardation/multiple anomaly syndrome usually involving more than 100 individual defects. Typical facies with upslanting palpebral fissures is the characteristic feature of this syndrome (hence the offensive designations "mongoloid idiocy" and "mongolism"). A wide range other defects, such as congenital heart diseases, respiratory disorders, and leukemia, may be associated. Down syndrome patients who survive into late adulthood may develop alzheimer syndrome.