Medical Genetics Trisomy 21 n+1 Sperm cell Zygote 2n+1 n(normal) In about 95%of all patients; Resulting from meiotic nondisjunction; 90%meiotic error responsible for the trisomy usually occurs during maternal meiosis; 10%occur in paternal meiosis; The risk increases with maternal age. This document is produced by trial version of Print2Flash.Visit www.print2flash.com for more informatiorThis document is produced by trial version of Print2Flash. Visit www.print2flash.com for more information