The gene responsible for sickle-cell disease is thought to have arisen from a mutation that protected against

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The gene responsible for sickle-cell disease is thought to have arisen from a mutation that protected against malaria. Individuals homozygous for the sickle-cell allele (SS) suffer from sickle-cell disease, but those heterozygous for the allele (AS) have protection against malaria. This is an example of balancing selection, as the heterozygous genotype confers an advantage in regions with high malaria incidence, while the homozygous recessive genotype results in a severe genetic disease.

The Gene Responsible for Sickle-Cell Disease Is Thought to Have