Male child with blood group AB is colourblind. His parents could be

Options

A. Father normal vision with blood group A, mother colourblind with group O
B. Father colourblind with group O, mother colourblind with blood gourp AB .
C. Father normal vision with blood group A, mother colourblind with blood group B
D. Father colourblind with blood group O, mother normal vision with blood group O.

Answer

To solve the question regarding the male child with blood group AB who is colorblind, we will analyze the genetic implications of the traits involved.

### Step-by-Step Solution:

1. **Understanding the Traits**:
- The male child has blood group AB and is colorblind.
- Blood group AB means he has one allele for A (IA) and one allele for B (IB).
- Colorblindness is an X-linked recessive trait, meaning it is carried on the X chromosome.

2. **Genotype of the Male Child**:
- Since the child is male, he has one X chromosome and one Y chromosome.
- His genotype for colorblindness can be represented as X^C Y (where X^C indicates the colorblind allele).

3. **Parental Genotypes**:
- The father must contribute the Y chromosome and one of the alleles for blood group (either A or B).
- The mother must contribute one X chromosome (which carries the colorblind allele) and one allele for blood group.

4. **Analyzing the Options**:
- **Option 1**: Father with normal vision (blood group A) and mother colorblind (blood group O).
- The father can be IAIO (blood group A) and the mother X^C X^C (colorblind, blood group O).
- This combination cannot produce a child with blood group AB. **Incorrect**.

- **Option 2**: Father colorblind (blood group O) and mother colorblind (blood group AB).
- The father would be X^C Y (colorblind, blood group O) and the mother would be X^C IA IB (blood group AB).
- This combination cannot produce a child with blood group AB. **Incorrect**.

- **Option 3**: Father with normal vision (blood group A) and mother colorblind (blood group B).
- The father can be IA Y (blood group A) and the mother can be X^C IB IO (colorblind, blood group B).
- The possible offspring can be X^C Y (colorblind male) and blood group AB (IA IB). **Correct**.

- **Option 4**: Father colorblind (blood group O) and mother normal vision (blood group C).
- This is incorrect because the mother cannot contribute a colorblind allele if she has normal vision. **Incorrect**.

5. **Conclusion**:
- The only viable option that allows for a male child with blood group AB and colorblindness is **Option 3**: Father with normal vision (blood group A) and mother colorblind (blood group B).