Q.35 The harmful allele of sickle-cell anaemia has not been eliminated from human population. Such afflicted people derive some other benefit. Discuss.
The mutant Hb5 type haemoglobin is found at high frequencies (up to 20% and above) in the tropical Africa.
It is known that heterozygotes (Hbs/HbA), having both types of haemoglobin show resistance to malarial infection because the body targets the Plasmodium falciparum infected cell for destruction. In contrast, individuals homozygous for normal haemoglobin
(HbA/HbA) suffer high mortality rates in early childhood due to malarial infection
Thus, the allele for sickle cells has been maintained because heterozygotes have a higher reproductive success than either of the two possible homozygotes.
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