Question

Haemophilia is more commonly seen in human males than in human females because

• A. This disease is due to an X-linked dominant mutation
• B. A greater proportion of girls die in infancy
• C. This disease is due to an X-linked recessive mutation
• D. This disease is due to a Y-linked recessive mutation

Answer 1

The correct option is C This disease is due to an X-linked recessive mutation

Haemophilia is an X-linked recessive disease. It occurs due to mutation in gene present on the X chromosome. It is most commonly seen in human males as males have only one copy of X chromosome and only one altered copy of the gene is sufficient to cause the disease. In females, there are two copies of X chromosomes and two altered copies of gene is required to cause the disease. Since it is recessive disease, one copy of altered gene in females will result in carrier state.

Thus, the correct answer is option C.