DOWN’S SYN­DROME

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Causes

Down syn­drome or Down’s syn­drome (DS) is a ge­netic con­di­tion that oc­curs as a re­sult of an ex­tra chro­mo­some (chro­mo­some 21).

The ex­tra chro­mo­some ap­pears due to an er­ror in cell divi­sion at con­cep­tion called nondis­junc­tion. The causes are un­known. (Source: Na­tional As­so­ci­a­tion for Down Syn­drome)

Types

Ac­cord­ing to the Amer­i­can Na­tional Down Syn­drome So­ci­ety, there are three types:

Tri­somy 21 (nondis­junc­tion – in which ev­ery cell in the body has an ex­tra copy of chro­mo­some 21) ac­counts for 95 per cent of cases.

Translo­ca­tion (when a piece of chro­mo­some 21 at­taches it­self to another chro­mo­some in a cell) ac­counts for about 4 pent of cases.

Mo­saicism (in which only some of the cells have an ex­tra copy of chro­mo­some 21) ac­counts for about 1 per cent of cases.

Facts

The older the mother, the higher the chances of the baby hav­ing DS. How­ever, ba­bies with DS are born to moth­ers of all ages and over half are born to moth­ers who are un­der 35. The in­ci­dence of DS among Emi­ratis in Dubai is one in ev­ery 320 births (1:319), higher than the world av­er­age of 1 in ev­ery 800 births (data re­leased by the Cen­tre for Arab Ge­nomic Stud­ies (CAGS))

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