A man suffering from haemophilia, married a normal woman whose father was haemophilic. What is the expected pattern in their children ?

Options

A. All son are affected but all daughters are normal
B. 50% of sons and 50% of daughters are affected
C. All daughters are affected but all sons are normal
D. 75% of the progeny is affected

Answer

To solve the problem of a man suffering from hemophilia marrying a normal woman whose father was hemophilic, we need to analyze the genetic inheritance pattern of hemophilia, which is an X-linked recessive disorder.

### Step-by-Step Solution:

1. **Identify the Genotypes**:
- The man is hemophilic, which means he has the genotype X^H Y (where X^H represents the hemophilic allele).
- The woman is normal but has a father who is hemophilic. This means she must carry one normal allele and one hemophilic allele, making her genotype X^H X (where X^H is the hemophilic allele inherited from her father and X is the normal allele).

2. **Determine Gametes**:
- The man can produce two types of gametes: X^H (hemophilic) and Y (normal).
- The woman can produce two types of gametes: X (normal) and X^H (hemophilic).

3. **Set Up a Punnett Square**:
- Create a Punnett square to visualize the possible combinations of alleles from the parents:
```
X X^H
----------------
X^H | X^H X | X^H X^H |
----------------
Y | X Y | X^H Y |
----------------
```

4. **Analyze the Offspring**:
- The potential genotypes of the offspring from the Punnett square are:
- X^H X (female carrier)
- X^H Y (affected male)
- X X (normal female)
- X Y (normal male)

5. **Determine the Phenotypes**:
- From the genotypes:
- X^H X: Carrier female (not affected)
- X^H Y: Affected male
- X X: Normal female
- X Y: Normal male

6. **Calculate the Ratios**:
- The offspring can be categorized as follows:
- 1 affected male (X^H Y)
- 1 carrier female (X^H X)
- 1 normal female (X X)
- 1 normal male (X Y)
- This results in:
- 50% of sons (1 out of 2) affected and 50% of daughters (1 out of 2) affected (1 carrier, 1 normal).

7. **Conclusion**:
- The expected pattern in their children is that 50% of sons and 50% of daughters are affected (where affected means being a carrier for daughters).

### Final Answer:
The expected pattern in their children is that **50% of sons and 50% of daughters are affected**.