How many genotypes are possible in Sickel-cell anamia ?

Options

A. 2
B. 3
C. 4
D. 1

Answer

To determine how many genotypes are possible in sickle-cell anemia, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Basics of Sickle-Cell Anemia**:
- Sickle-cell anemia is a genetic disorder caused by a mutation in the gene that encodes the beta chain of hemoglobin. This mutation leads to the production of abnormal hemoglobin, known as HbS.

2. **Identify the Alleles**:
- There are two main alleles involved in sickle-cell anemia:
- **HbA**: Normal hemoglobin allele.
- **HbS**: Sickle-cell hemoglobin allele.

3. **Determine Possible Genotypes**:
- Genotypes are combinations of alleles that an individual can inherit. The possible combinations of the alleles are:
- **HbA HbA**: Homozygous normal (no sickle-cell disease).
- **HbA HbS**: Heterozygous (carrier of sickle-cell trait, does not have the disease).
- **HbS HbS**: Homozygous sickle-cell (has sickle-cell disease).

4. **Count the Genotypes**:
- From the combinations identified, we can see that there are three distinct genotypes:
- HbA HbA
- HbA HbS
- HbS HbS

5. **Conclusion**:
- Therefore, the total number of possible genotypes for sickle-cell anemia is **3**.

### Final Answer:
- The number of possible genotypes in sickle-cell anemia is **3**.