Question

Genetic disorder in Africans which reduces oxygen uptake is:

• A. Phenylketonuria
• B. Haemophilia
• C. Colour blindness
• D. Sickle cell anemia

Answer 1

The correct option is D

Sickle cell anemia

The correct option is D:

Explanation of the correct option:

1. Sickle cell anemia is an autosomal disease that is the most common genetic disorder in Africans.
2. The disease is based on the substitution of the sixth codon in the gene that codes for the $\beta$-chain of hemoglobin.
3. For this reason, the sixth amino acid in the $\beta$-chain of hemoglobin, glutamic acid, is replaced by valine.
4. The main symptom of this disorder is a decrease in oxygen uptake.

Explanation of the incorrect options:

Option A:

1. The congenital disability that causes an amino acid to build up in the body is called phenylketonuria (PKU).
2. In a child with PKU, phenylalanine cannot be converted to tyrosine because the enzyme phenylalanine hydroxylase is not working properly.
3. This leads to dangerously high levels of phenylalanine, which build up in the blood and become toxic to the brain and nervous system.

Option B:

1. Haemophilia is a disorder in which the blood does not clot normally.
2. Excessive bleeding (external and internal) occurs after injury or damage when blood is unable to clot properly.

Option C:

A reduced ability to distinguish between certain colors is color blindness.

Final answer: Genetic disorder in Africans which reduces oxygen uptake is sickle cell anemia.