Hemoglobinopathies are providing one of the few convincing demonstrations of selection, influencing the frequency of a single gene in the human population. The high rate of disorders, such as the sickle cell anemia and beta-thalassemia that occur in the subtropical or tropical regions within the strip affected by malaria, led Haldane to propose that malaria may be the selective agent responsible for balancing the loss of thalassemia and sickle cell anemia genes due to the early death of homozygous patients. But a new proposal appeared to explain the maintenance of these polymorphisms, based on the differential fertility or parental effect. Some authors observed a distortion favoring the transmission of mutant alleles in non-endemic malaria areas. Based on these observations, the authors proposed a maternal effect to explain these distortions. This study aims at presenting a review of the mechanisms involved in the maintenance of polymorphisms of hemoglobinopathies, both from the classic model and the recently published alternative hypotheses.
Hemoglobinopathies; malaria; genetic polymorphism; maternal effect