Congenital disorder caused by an extra chromosome (trisomy) on the chromosome 21 pair. Those with the syndrome may have broad, flat faces; up-slanted eyes, sometimes with epicanthal folds (whence its former name, mongolism); intellectual disability (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.
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District (pop., 1999 est.: 63,800), Northern Ireland. Formerly part of County Down, it was established as a district in 1973. It fronts Strangford Lough and the Irish Sea. Extreme southern and western Down is mountainous; the dome-shaped Mourne Mountains reach an elevation of 2,789 ft (850 m). Down is a rich agricultural district; livestock raising is important. Down was settled in prehistoric times. It was where St. Patrick began his mission in Ireland (AD 432), and his well and bathhouses are preserved near the district seat, Downpatrick. In Tudor times, parts of Down were colonized by English and Scottish adventurers.
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