The probability of having a haemophilia carrier daughter by a haemophilia carrier mother and a normal father is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 25%
Hemophilia is an X-linked recessive disorder. A carrier mother has one normal X chromosome and one hemophilia-carrying X chromosome (XhY). A normal father has one normal X chromosome and one normal Y chromosome (XY).
Cross Analysis:
When we cross the genotypes, we get four possible combinations for their children:
- X (from father) and X (from mother) → XX (normal daughter)
- X (from father) and Xh (from mother) → XhX (carrier daughter)
- Y (from father) and X (from mother) → XY (normal son)
- Y (from father) and Xh (from mother) → XhY (hemophilic son)
Probability Calculation:
Out of these four possibilities:
There is one carrier daughter genotype XhX out of the total four possible outcomes.
So:
- Probability of having a carrier daughter = \(\frac{1}{4}\) = 25%