Question

What is the probability that a daughter from a carrier female (XᴴXʰ) and haemophilic male (XʰY) will be haemophilic?

Options

• 50%

• 100%

• 75%

• 25%

Answer 1

A carrier female (XᴴXʰ) can pass either Xᴴ or Xʰ to daughters. A haemophilic male (XʰY) always passes Xʰ to daughters. Therefore, daughters can be XᴴXʰ (carrier, 50%) or XʰXʰ (haemophilic, 50%). The probability of a daughter being haemophilic is 50%.