Question

A haemophilic man marries a normal homozygous woman. What is the probability that their son will be haemophilic?

विकल्प

• 100%

• 75%

• 50%

• 0%

Answer 1

0%

Explanation:

Haemophilia is a sex-linked recessive disorder carried on the X chromosome. A haemophilic man has the genotype X^hY (where X^h is the affected X chromosome) and the normal homozygous woman has the genotype XX. When they have sons, the sons inherit the Y chromosome from the father (because males are XY) and one X chromosome from the mother. Since the mother is normal and has only normal X chromosomes, all the sons will inherit a normal X chromosome and will therefore be normal (not haemophilic). Hence, the probability that their son will be haemophilic is 0%.