Sickle-cell disease is a debilitating disease that results from being homozygous recessive for the "sickle-cell allele" of a hemoglobin gene. Why is the allele present and even common in many human populations?

Heterozygote advantage

Explanation:

The sickle cell allele in a heterozygote state confers a kind of resistance to malaria in areas where the disease is endemic while it is deleterious in homozygous condition. Hence, this heterozygote advantage ensures that the recessive allele is present and quite common in the population.

what have scientists found to be the most efficient and effective way to insert new sequences into an individual? a-scientists have created genetically altered foods that release dna during digestion. b-scientists use viruses to insert specific gene sequences. c-scientists irradiate genes so that they can be absorbed through the skin.