Final answer:
Sickle cell anemia is an autosomal recessive disorder caused by a mutation in the beta-globin gene and characterized by sickle-shaped red blood cells. Heterozygous carriers have a fitness advantage in areas where malaria is prevalent. Beta-thalassemia is a related anemia condition involving mutations that reduce hemoglobin levels.
Step-by-step explanation:
The question at hand relates to the genetic disorder known as sickle cell anemia. This condition is an autosomal recessive disorder, meaning that it is typically inherited when two copies of the mutated allele are present. Sickle cell anemia is characterized by a mutation in the beta-globin gene which affects hemoglobin's structure, leading to the characteristic sickle shape of the red blood cells. This disorder can result in severe anemia, blockages in blood vessels, pain, organ damage, and can be potentially lethal.
In regions where malaria is endemic, individuals with one mutated allele (heterozygotes) for sickle cell anemia have been found to possess resistance to malaria, thereby increasing their fitness. This is because the presence of the sickle allele in a heterozygous state offers some protection without causing the full-blown disease that occurs in homozygous individuals. Consequently, there is a selective advantage for carriers in such regions, which explains the prevalence of the sickle cell allele in populations from malaria-endemic areas. On the other hand, beta-thalassemia is another form of anemia caused by mutations that affect hemoglobin production, which can also include mutations in the promoter region of the beta-globin gene, leading to low levels of hemoglobin.