Question

Which human chromosomes are involved in Down’s syndrome?

(a) 6

(b) 14 and 21

(c) 8 and 12

(d) X and Y

I had been asked this question in class test.

Question is taken from Chromosomal Abnormalities : Duplication topic in section Chromosomal Basis of Inheritance of Cytogenetics

Answer 1

The correct answer is (b) 14 and 21

The best explanation: In Down’s syndrome a part of the 21^st chromosome’s long arm duplicates and transfers to chromosome 14’s long arm.