Fig. 2

SNP array results and mechanisms for mosaic trisomy 22. A Mosaic trisomy 22 in case 13 arose from mitotic nondisjunction without crossover, with mosaic trisomy 22 cells accounting for 80% of the total. A mitotic origin was suggested by the absence of a third haplotype, indicated on the SNP array by shifts in the B allele frequency, corresponding to a shift in B allele frequency from 50% towards 33%, and a shift from 50% toward 66%. B Mosaic trisomy 22 in case 14 arose from meiotic II nondisjunction with a frequency of 30%. The additional haplotypes are observable near the telomeres, but not at the centromere, which is consistent with a meiosis II origin, where sister chromatids undergo non-disjunction with two crossovers. C Mosaic trisomy 22 in case 15 arose from meiotic I nondisjunction with a frequency of 15%. The additional haplotypes are visible proximal to the centromere with one crossover