Question

Heterozygous sickle cell anemia (sickle cell trait) gives protection against:

• A. G6PD deficiency
• B. Malaria
• C. Thalassemia
• D. Dengue fever

Hint:

Think of the famous heterozygote advantage in malaria-endemic zones.

Answer 1

The Correct Option is B

Step 1: The concept of balanced polymorphism.
Sickle cell trait persists in malaria-endemic regions because carrying one sickle gene gives a survival advantage against malaria. This is the classic example of heterozygote advantage.

Step 2: Why it protects against malaria.
In heterozygotes, red cells infected by Plasmodium falciparum tend to sickle and are cleared by the spleen, and the intracellular environment is unfavorable for the parasite. This reduces parasite multiplication and severity of malaria.

Step 3: Rule out the others.
G6PD deficiency is a separate enzyme defect, not something sickle trait protects against (G6PD deficiency itself also gives some antimalarial protection, but it is not protected against by sickle trait).
Thalassemia is a different inherited hemoglobin disorder, unrelated.
Dengue is a viral infection with no link to sickle trait.

Step 4: Conclusion.
Heterozygous sickle cell anemia protects against malaria, option B.