Question

Sam’s maternal grandfather is haemophilic. His father and mother are non- haemophilic but mother is a carrier.Based on this information which of the following will be true for Sam.

• A. Sam will definitely be haemophilic.
• B. There is a 50% chance of Sam being haemophilic.
• C. Sam will definitely be non haemophilic.
• D. Sam will be non-haemophilic but a carrier.

Answer 1

The correct option is B

There is a 50% chance of Sam being haemophilic.

Sam’s maternal grandfather is haemophilic. His mother is a carrier which means that the haemophilia gene is transferred to his mother from his grandfather. His father is non-haemophilic, if Sam receives the haemophilia gene from his mother he will be haemophilic and if he receives normal X gene from his mother he will be non-haemophilic. Therefore, there is 50-50 chance of Sam being haemophilic.