Male downs syndrome genotype-: (A) 46 XY, (B) 47 XY, (C) 45 XY, (D) 47 XXY
Answer is B. Ans. is 'b' i.e., 47 XY o 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 robertsonian translocation, n t(13 : 21)t(14 : 21)t(15 : 21)Very rarely long arm of chromosome 21 is triplicate (Partial trisomy).