Question:easy
Heterozygous sickle cell anemia (sickle cell trait) gives protection against:
Heterozygous sickle cell anemia (sickle cell trait) gives protection against:
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Think of the famous heterozygote advantage in malaria-endemic zones.
Updated On: Jun 24, 2026
- G6PD deficiency
- Malaria
- Thalassemia
- Dengue fever
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The Correct Option is B
Solution and Explanation
This is a population-genetics classic. A gene that causes disease in the homozygous state can still spread in a population if carrying just one copy helps survival. Sickle cell trait is the textbook case of this heterozygote advantage.
The selective pressure is falciparum malaria. People with one sickle gene handle the infection better: parasitised red cells deform and sickle, the spleen pulls them out of circulation early, and conditions inside the cell hinder the parasite. The net result is milder malaria and better survival, which keeps the sickle gene common exactly where malaria is common.
Run through the distractors. G6PD deficiency is its own enzyme disorder; sickle trait does not shield against it. Thalassemia is a separate globin-chain disorder with no protective link. Dengue is caused by a virus and has nothing to do with the red-cell changes of sickle trait.
So the protection conferred is specifically against malaria.
\[\boxed{\text{Malaria (option B)}}\]
The selective pressure is falciparum malaria. People with one sickle gene handle the infection better: parasitised red cells deform and sickle, the spleen pulls them out of circulation early, and conditions inside the cell hinder the parasite. The net result is milder malaria and better survival, which keeps the sickle gene common exactly where malaria is common.
Run through the distractors. G6PD deficiency is its own enzyme disorder; sickle trait does not shield against it. Thalassemia is a separate globin-chain disorder with no protective link. Dengue is caused by a virus and has nothing to do with the red-cell changes of sickle trait.
So the protection conferred is specifically against malaria.
\[\boxed{\text{Malaria (option B)}}\]
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