Down syndrome is due to non-disjunction of?
Ans. is 'a' i.e., 21 Chromosome 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) o t (14 : 21) t (15 : 21) Very rarely long arm of chromosome 21 is triplicate (Paial trisomy).
21
18
11
15