Is Sickle Cell Trait as Benign as is Usually Assumed?

Sickle cell anemia is a disease which results from the inheritance of two hemoglobin S (Hb S) genes. Sickle-cell anemia individuals are referred to as Hb SS patients, and are known to suffer from a variety of life-threatening symptoms. Paramount in the clinical complications of sickle cell patients is the "sickle-cell crisis". If a crisis is not stopped by prompt medical attention, it may result in death. It is becoming increasingly clear that some sickle cell anemic patients have more benign clinical profiles than do others. The genetic reason for such clinical differences has been well determined: although the mutation that changes the "normal" hemoglobin gene is the same in all patients, the genetic material outside of the gene influences how the gene is expressed. This genetic material is referred to as the beta-globin haplotype. Carriers of the sickle cell gene are referred to as Hb AS individuals. Hb AS carriers usually have a normal life free of the clinical problems associated with the disease suffered by sickle cell patients. However, it is becoming increasingly clear that under strenuous situations, some Hb AS carriers do experience heat illness and other life threatening problems while others do not. The purpose of this project is to determine if there is a genetic reason for why some athlete carriers of the sickle cell trait experience heat illness, while others do not. Although the genetic reason for the different clinical outcomes of sickle cell anemic patients is now well understood (different haplotypes result in different disease courses), the possibility that the same haplotypes might be the reason why some sickle cell carriers have worse clinical profiles has never been explored. In this project we will work with a sickle-cell trait registry of athletes, and we will test the haplotypes of Hb AS athletes who have and who have not had heat illness. Our study is the first to attempt to clarify if there is a genetic reason for this occurrence. Total participation time for the study is thirty minutes or less. Information provided by the participant will be analyzed within one year of participation. Deidentified results will be kept for five years, per the University of South Florida's Institutional Review Board protocol, and will be available upon request to the principal investigator. Participants can do complete the study in under half an hour in the privacy of their own home.