Question

The gene for haemophilia is located on 'X' chromosome. Hence it is normally impossible for

• A. Haemophilic father to pass the gene to this daughter
• B. Carrier mother to pass the gene to her daughter
• C. Carrier mother to passes the gene to her son
• D. Haemophilic father to pass the gene to his son

Answer 1

The correct option is D Haemophilic father to pass the gene to his son

Haemophilia is a X-linked recessive disorder in which person do not produce clotting factor. Female have XX chromosome in which one X is affected and one X is normal. When she inherit affected X chromosome she has second normal chromosome which compensates the haemophilic gene and thus, called as a carrier. But haemophilic father (XY) inherit haemophilia to all his daughter because she carries one X from father and one from mother whereas none of his sons will be affected because he carries only Y chromosome from his father. Thus, the correct answer is option D.