Down syndrome
Translation- Down syndrome
-
a genetic disorder, associated with the presence of an extra chromosome 21, characterized by mild to severe mental retardation, weak muscle tone, a low nasal bridge, and epicanthic folds at the eyelids.[1960-65; after John L. H. Down (1828-96), British physician]
* * *
or trisomy 21Those with the syndrome may have broad, flat faces; up-slanted eyes, sometimes with epicanthal folds (whence its former name, mongolism); mental retardation (usually moderate); heart or kidney malformations; and abnormal fingerprint patterns. Many persons with Down syndrome can live and work independently or in a sheltered environment, but they age prematurely and have a short (55-year) life expectancy. The risk of bearing a child with the disorder increases with the mother's age; it can be detected in the fetus by amniocentesis.* * *
congenital disorder caused by an extra chromosome (chromosome number) on the chromosome 21 pair, giving the person a total of 47 chromosomes rather than the normal 46. British physician John Langdon Down first described the physical features of the disorder in 1866, and thus the disorder was later named for him. The physical and mental impacts of Down syndrome range from mild to severe. Some common physical signs of the disorder include a small head, flattened face, short neck, up-slanted eyes, low-set ears, enlarged tongue and lips, and sloping underchin. Other characteristics of the disorder may include poor muscle tone, heart or kidney malformations (or both), and abnormal dermal ridge patterns on the palms of the hands and soles of the feet. Intellectual disability occurs in all persons with Down syndrome and usually ranges from mild to moderate. congenital heart disease is found in about 40 percent of people with Down syndrome.There are three forms of Down syndrome. The most common form is trisomy 21, in which all of an individual's cells contain three, as opposed to two, copies of chromosome 21. The extra chromosome, identified in 1959 by French geneticist Jérôme-Jean-Louis-Marie Lejeune, is a result of random, abnormal events in cell division that occur during embryonic development or during the development of egg or sperm cells. The presence of the extra chromosome in cells gives rise to the signs and symptoms of Down syndrome. In mosaic Down syndrome, a rare form of the disorder, only some of an individual's cells contain a third copy of the chromosome. Because there are some cells that retain the normal 46 chromosomes, certain aspects of the disorder, such as intellectual disability, are not as severe in people with mosaic Down syndrome relative to people with trisomy 21. The third form, translocation Down syndrome, occurs when the extra chromosome in the 21 pair breaks off and attaches itself to another chromosome. Translocation Down syndrome is the only form that may be inherited. A parent who possesses a balanced translocation—a chromosome rearrangement with no extra genetic material from chromosome 21—can pass the translocation to an offspring. Carriers of balanced translocations do not have signs or symptoms of the disorder. Mothers carrying a translocation have a 12 percent risk of transmitting the genetic rearrangement to their offspring, whereas fathers carrying a translocation have a 3 percent risk of transmission.Down syndrome occurs in about 1 in every 740 live births. The incidence of the disorder increases markedly in the offspring of women over the age of 35. For example, the incidence of the disorder in the offspring of young women is only about 1 in 1,000, whereas its incidence in the offspring of women over age 40 can range from about 1 in 100 to 1 in 30. In addition, women who have had one child with Down syndrome have a 1 percent chance of having a second child with the disorder. Screening tests using both ultrasound and blood analysis that are performed between the 11th and 14th week of pregnancy can detect most incidences of Down syndrome. In cases where Down syndrome is suspected, the disorder can be confirmed using amniocentesis or chorionic villus sampling. In these diagnostic tests, samples of fetal cells are taken from the amniotic fluid or from the mother's placenta and analyzed for the presence of the abnormal chromosome.With modern medical care, many persons with Down syndrome live into adulthood, although they do have a shorter life expectancy (55) than normal adults, because they develop the degenerative conditions of old age prematurely. Complications associated with Down syndrome include major heart defects that cannot be corrected by surgery, infection such as pneumonia, and leukemia. Depending on the severity of intellectual disability, some people with Down syndrome never become self-supporting. However, the majority can be taught to contribute usefully in the home or in a sheltered working or living environment after they are grown. There are no drugs designed to treat Down syndrome because little is known about the exact molecular mechanisms that give rise to the symptoms of the disorder. However, scientists have identified a gene on chromosome 21 that disrupts normal embryonic cell development in trisomy 21 and may cause the manifestation of certain symptoms. As a result, this gene is a potential target for the generation of therapeutic agents capable of alleviating symptoms of Down syndrome.* * *
Universalium. 2010.
Look at other dictionaries:
Down syndrome — Classification and external resources Boy with Down syndrome assembling a … Wikipedia
Down syndrome — Down syndrome. См. болезнь Дауна. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
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 retardation, a… … The Collaborative International Dictionary of English
Down syndrome — A common chromosome disorder due to an extra chromosome number 21 (trisomy 21). Down syndrome causes mental retardation, a characteristic face, and multiple malformations. Down syndrome is a relatively common birth defect. The chromosome… … Medical dictionary
Down syndrome — noun Etymology: J. L. H. Down died 1896 English physician Date: 1961 a congenital condition characterized by moderate to severe mental retardation, slanting eyes, a broad short skull, broad hands with short fingers, and trisomy of the human… … New Collegiate Dictionary
down syndrome — болезнь Дауна … Большой англо-русский и русско-английский словарь
Down syndrome — Дауна синдром … Англо-русский офтальмологический словарь
Down syndrome — noun Condition caused by a chromosomal excess, whereby the patients bear a certain resemblance to the Mongoloid race, such as a small head and tilted eyelids. Syn: trisomy 21 … Wiktionary
Down syndrome — синдром (болезнь) Дауна НЗЧ, обусловленное трисомией по хромосоме 21 нормального хромосомного набора, характеризуется умственной отсталостью и своеобразным внешним обликом (в случаях легких проявлений синдрома больные поддаются коррекции);… … Англо-русский толковый словарь генетических терминов
Down syndrome — 1) Общая лексика: синдром Дауна 2) Медицина: даунизм (врожденное нарушение развития, обусловленное наличием 21 лишней хромосомы и проявляющееся умственной отсталостью, нарушением роста костей и другими физическими аномалиями), трисомия 21,… … Универсальный англо-русский словарь
Фильмы
- Prolific Oil, 1987 — Movie 2nd cycle of the Energy Strategy for the party. " On the development of fuel-energy base of the USSR, problems and prospects of our energy, drama and energy problems in different periods of history.
Joomla, 
Drupal, 
WordPress, MODx.