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 1: Understand the Genetics of Sickle Cell Anemia
Sickle cell anemia is an autosomal recessive disorder caused by mutations in the hemoglobin gene. The two alleles involved are:
- HbA (normal hemoglobin)
- HbS (sickle-shaped hemoglobin)

### Step 2: Identify the Possible Genotypes
Since sickle cell anemia is controlled by a single pair of alleles, we can outline the possible combinations of these alleles:
1. Homozygous Normal: HbA HbA
2. Heterozygous Carrier: HbA HbS
3. Homozygous Sickle Cell: HbS HbS

### Step 3: Analyze Each Genotype
- **HbA HbA**: This genotype represents a normal individual who does not have sickle cell anemia.
- **HbA HbS**: This genotype represents a carrier who does not show symptoms of the disease but can pass the sickle cell allele to offspring.
- **HbS HbS**: This genotype represents an individual with sickle cell anemia, which is typically lethal before maturity.

### Step 4: Count the Genotypes
From the combinations identified, we can conclude that there are three possible genotypes for sickle cell anemia:
1. HbA HbA
2. HbA HbS
3. HbS HbS

### Conclusion
Thus, the total number of genotypes possible in sickle cell anemia is **3**.

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