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1

Trisomy 21

Non-disjunction Robertsonian Translocation Mosaicism

in meiosis I

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in meiosis II in meiosis I

24 24 22 22 24 22 23 23

A B C

= chr 21

21

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3

chr 21

The resulting embryo would be expected to show Trisomy 21 1-2% of clinically recognized Down Syndrome