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

Hemophilia is inherited in an X-linked recessive pattern.
A condition is considered X-linked when gene mutation that causes it is located on the X chromosome, one of the two sex chromosomes.
In males (who have only one X chromosome), one altered copy of the gene in each cell is enough to cause the condition.
Since females have two X chromosomes, a mutation must be present in both copies of the gene to cause hemophilia.
Males are affected by X-linked recessive disorders much more frequently than females.
A major characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.