Trisomy 21: Difference between revisions

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 Trisomy 21 is the name given to the most common occuring mutation that leads to [[Down's syndrome|Down's syndrome]]. "Trisomy" because, due to a nondisjunction event (failed separation of the chromosome), there is an extra copy of chromosome 21 in the gamete. And "21" states that the trisomy occurs on chromosome 21.   
 Trisomy 21 is the name given to the most common occuring mutation that leads to [[Down's syndrome|Down's syndrome]]. "Trisomy" because, due to a nondisjunction event (failed separation of the chromosome), there is an extra copy of chromosome 21 in the gamete. And "21" states that the trisomy occurs on chromosome 21.   


The non-disjuntion event describes the failure of the chromosome pairs to separate properly during meiosis, either stage 1 or stage 2, such that one of the gametes will contain 1 chromosome 21 and one will contain 1 more, the latter being the trisomy.
The non-disjuntion event describes the failure of the chromosome pairs to separate properly during meiosis, either stage 1 or stage 2, thus leading to the trisomy of chromosome 21 where an extra copy of the chromosome is added.

Revision as of 17:46, 19 October 2012

 Trisomy 21 is the name given to the most common occuring mutation that leads to Down's syndrome. "Trisomy" because, due to a nondisjunction event (failed separation of the chromosome), there is an extra copy of chromosome 21 in the gamete. And "21" states that the trisomy occurs on chromosome 21. 

The non-disjuntion event describes the failure of the chromosome pairs to separate properly during meiosis, either stage 1 or stage 2, thus leading to the trisomy of chromosome 21 where an extra copy of the chromosome is added.