Question

A woman with cystic fibrosis ,an autosomal recessive condition marries her first cosin.What is the risk that their first child will have cystic fibrosis ?
A. `1//4`
B. `1//2`
C. `3//4`
D. `1//8`

Answer 1

Correct Answer - D
The gentoype of affected woman is cc. Her parents are obligate carries (Cc) and one of her grand parents must also be a carrier. Her first cousin then has a 1/4 chance being a carrier.He has 1/2 chance of transnmitting his c allete if it is present.So the chance of child being a patient of cystic fibrosis is `1//4xx1//2=1//8`