Trisomy 21: Difference between revisions
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Trisomy 21 is the name given to the [[Non disjunction|non-disjunction]] of [[Homologous chromosomes|homologous pairs of chromosomes]] 21 which leads to [[Down's syndrome|Down syndrome]]. "[[Trisomy|Trisomy]]" because, due to a nondisjunction event (failed separation of the [[Chromosome|chromosome]] pairs to separate during stage 1 or 2 of [[Meiosis|meiosis]]), there is an extra copy of [[Chromosome 21|chromosome 21]] in one of the gametes. At [[Fertilisation|fertilisation]], this [[Gamete|gamete]] will cause the [[Zygote|zygote]] to contain 3 copies of the chromosome 21. | Trisomy 21 is the name given to the [[Non disjunction|non-disjunction]] of [[Homologous chromosomes|homologous pairs of chromosomes]] 21 which leads to [[Down's syndrome|Down syndrome]]. "[[Trisomy|Trisomy]]" because, due to a nondisjunction event (failed separation of the [[Chromosome|chromosome]] pairs to separate during stage 1 or 2 of [[Meiosis|meiosis]]), there is an extra copy of [[Chromosome 21|chromosome 21]] in one of the gametes. At [[Fertilisation|fertilisation]], this [[Gamete|gamete]] will cause the [[Zygote|zygote]] to contain 3 copies of the chromosome 21.<br> | ||
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Latest revision as of 14:43, 9 December 2018
Trisomy 21 is the name given to the non-disjunction of homologous pairs of chromosomes 21 which leads to Down syndrome. "Trisomy" because, due to a nondisjunction event (failed separation of the chromosome pairs to separate during stage 1 or 2 of meiosis), there is an extra copy of chromosome 21 in one of the gametes. At fertilisation, this gamete will cause the zygote to contain 3 copies of the chromosome 21.