Question

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

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

Answer 1

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

Haemophilia is a X-linked recessive trait. The gene of haemophilia is found on X-chromosome. Haemophilia is more commonly found in females because it is a recessive disease and the homozygous condition is lethal. Females having only X chromosome carrying the gene for haemophilia are carriers. Males have only one X chromosome, hence haemophilia is more common in males because this recessive trait is expressed in males due to one X-chromosome.

So, the correct answer is 'This disease is due to an X-linked recessive mutation'.