Down's syndrome

Down's syndrome
= Down syndrome
a condition resulting from a chromosomal abnormality most commonly due to the presence of three copies of chromosome 21 (trisomy 21), which is most likely to occur with advanced maternal age. Down's syndrome can also occur as a result of chromosomal rearrangement (translocation) and as part of a mosaicism, which are not related to maternal age. Affected individuals share certain clinical features, including a characteristic flat facial appearance with slanting eyes (as in Mongolian races, which gave the former name, mongolism, to the condition), broad hands with short fingers and a single crease across the palm, malformed ears, eyes with a speckled iris (Brushfield spots), short stature, and hypotonia. Many individuals also have a degree of mental retardation, although the range of ability is wide and some individuals are of normal intelligence. The incidence of congenital heart defects is 40–50%, and other structural malformations (e.g. duodenal atresia) and associated abnormalities (e.g. deafness, squints, obesity, type 2 diabetes) may also be present.
Prenatal diagnosis of Down's syndrome can be obtained by amniocentesis and chorionic villus sampling, which are invasive procedures, and about 33% of structural abnormalities in fetuses with Down's can be detected prenatally by ultrasonography. Prenatal screening tests (e.g. the triple test) and soft ultrasound markers (e.g. nuchal translucency scanning) can estimate the risk of Down's syndrome being present. [L. H. Down (1828–96), British physician]

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  • Down's syndrome — Down syndrome Down syn drome, Down s syndrome Down s syn drome, n. (Med.) A congenital disorder caused by an extra chromosome 21 in some or all cells. It causes a variable number and degree of abnormalities, including retarded growth, mental… …   The Collaborative International Dictionary of English

  • Down's syndrome — ► NOUN Medicine ▪ a congenital disorder causing intellectual impairment and physical abnormalities. USAGE Down s syndrome is the accepted term in modern use, and former terms such as mongol and mongolism, which are likely to cause offence, should …   English terms dictionary

  • Down's syndrome — Down s ,syndrome noun uncount DOWN SYNDROME …   Usage of the words and phrases in modern English

  • Down's syndrome — Down s .syndrome n [U] [Date: 1900 2000; Origin: J. H. L. Down (1828 96), English doctor] a condition that someone is born with, that stops them from developing in a normal way, both mentally and physically …   Dictionary of contemporary English

  • Down's Syndrome — 1961, from J.L.H. Down (1828 1896), English physician; chosen as a less racist name for the condition than earlier MONGOLISM (Cf. mongolism) …   Etymology dictionary

  • Down's syndrome — N UNCOUNT Down s syndrome is a disorder that some people are born with. People who have Down s syndrome have a flat forehead and sloping eyes and lower than average intelligence. (in AM, usually use Down syndrome) …   English dictionary

  • Down's syndrome — a condition resulting from a genetic abnormality in which an extra chromosome is present (there are three no. 21 chromosomes instead of the usual two), giving a total of 47 chromosomes rather than the normal 46. The chances of having a Down s… …   Medical dictionary

  • Down's syndrome —    a congenital disorder due to a chromosome deficiency    This is an example of a phrase incorporating syndrome being used to avoid a taboo word in this case what was formerly known as Mongolism. Here the stigma and the possible racial sneer are …   How not to say what you mean: A dictionary of euphemisms

  • Down's syndrome — noun Medicine a congenital disorder causing intellectual impairment and physical abnormalities including short stature and a broad facial profile. Origin 1960s: named after the 19th cent. English physician John L. H. Down. Usage Of relatively… …   English new terms dictionary

  • Down's syndrome — UK [ˈdaʊnz ˌsɪndrəʊm] / US [ˈdaʊnz ˌsɪndroʊm] noun [uncountable] medical a medical condition that someone is born with, that makes them develop in a different way from most people, mentally and physically. Down s syndrome is often simply called… …   English dictionary

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