Sickle-Cell Anemia Is a Disease That Alters the Structure of Hemoglobin

question 19

Essay

Sickle-cell anemia is a disease that alters the structure of hemoglobin, and in turn, can cause severe health problems in individuals if left untreated. The disease is expressed in homozygous recessive individuals, whereas the heterozygous condition usually does not result in any symptoms of the disease. Sickle-cell anemia primarily affects Africans and Caucasians of Mediterranean descent. Typically, when a disease occurs only in the homozygous recessive condition, the incidence of the gene in the population is predicted to decline overtime, particularly when it can be detected either phenotypically or by genetic testing. In East Africa, the disease still occurs in about 40% of the population. Give an explanation for why the incidence of the disease has remained so high in African populations.