Male downs syndrome genotype?

Ans. is 'b' i.e., 47 XY In 95% of cases of Down syndrome-trisomy of 21:? Extra chromosome is of maternal in origin. 1% have mosaic with some all have 46 chromosome. 4% have robesonian translocation. t (13 : 21) t (14 : 21) at (15 : 21) Very rarely long arm of chromosome 21 is triplicate (Paial trisomy).