Sickle Cell Trait and Competitive Athletics: Is There a Risk?

Abstract

The gene for sickle hemoglobin has a nearly global distribution, occurring with great frequency in Africa (and from there to the Western Hemisphere), southern Europe, the Mideast, and parts of the Indian subcontinent. In the homozygous state, homozygosity for sickle cell genes (sickle cell anemia) produces great concentrations of sickle hemoglobin [HbS] within the RBCs, usually >90%. Such large concentrations of HbS are associated with spontaneous sickling under physiologic conditions in vivo that result in severe hemolytic anemia and vasooclusive complications that compromise and threaten health, and even survival. In contrast, the heterozygous state, designated sickle cell trait, is associated with only 30% to 40% HbS in the RBCs, most of the remainder being normal adult hemoglobin (HbA). These relatively small concentrations of HbS are not associated with in vivo sickling.