If a child is born with sickle - cell anaemia then his /her parents must be :

Options

A. Homozygous
B. Heterozygous
C. Co - dominant
D. Nullizygous

Answer

To solve the question regarding the inheritance of sickle cell anemia, we can follow these steps:

### Step 1: Understand the Genetics of Sickle Cell Anemia
Sickle cell anemia is caused by a mutation in the hemoglobin gene, which is located on chromosome 11. It is an autosomal recessive disorder. This means that a person must inherit two copies of the mutated gene (one from each parent) to express the disease.

### Step 2: Determine the Genotype of the Child
If a child is born with sickle cell anemia, the child must have the genotype "hh" (homozygous recessive), where "h" represents the sickle cell allele.

### Step 3: Infer the Genotypes of the Parents
Since the child has sickle cell anemia (hh), both parents must carry at least one copy of the sickle cell allele. The possible genotypes for the parents can be:
- Both parents are homozygous recessive (hh).
- One parent is homozygous recessive (hh) and the other is heterozygous (Hh).
- Both parents are heterozygous (Hh).

However, for the child to be homozygous recessive (hh), at least one parent must be homozygous recessive. Therefore, both parents must carry the sickle cell allele.

### Step 4: Conclusion
Thus, the parents of a child with sickle cell anemia must be either:
- Homozygous recessive (hh) or
- Heterozygous (Hh) but at least one must be homozygous (hh) for the child to inherit the sickle cell anemia.

### Final Answer
The correct answer is that the parents must be homozygous recessive (hh) or at least one of them must be homozygous recessive.

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