Question

In a family father is affected by Down syndrome and mother is normal then what will be percentage of affected offspring :-

• A. 50 %
• B. 100 %
• C. 25 %
• D. 75 %

Answer 1

The correct option is A 50 %

Down syndrome is a genetic disorder caused by trisomy of an autosome, chromosome number 21. In a family where father is affected by down syndrome and mother is normal, the percentage of affected offspring will be 50% as there's a 50% likelihood for the offsprings to obtain an extra copy of the chromosome 21 from the father.

So, the correct option is '50%'.