Lecture9DownSyndrome_000

Most non discjuntion events occur in meiosis i when

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Unformatted text preview: omy 21 (47,XX,+21) is the cause of approximately 96% of observed Down syndrome cases, with 88% coming from non-disjunction in the maternal gamete and 8% coming from non-disjunction in the paternal gamete. Most non-discjuntion events occur in Meiosis I When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21. Robertsonian translocations cause 2-3% of Down syndrome cases. Meiosis contains two steps in which chromosomes are segregated into two different cells AnimaEon: h0p://www.sumanasinc.com/webcontent/animaEons/content/meiosis.html Figure 17 ­47...
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This note was uploaded on 01/07/2013 for the course BIMM 100 taught by Professor Pasquinelli during the Spring '06 term at UCSD.

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