Sickle Cell Trait and Splenic Syndrome-Reply

In Reply.— Dr Steinberg's letter raises two interesting questions. The first is whether α-thalassemia protects blacks with sickle cell trait from high-altitude splenic syndromes. Approximately 30% of blacks with sickle cell trait also have α-thalassemia. These individuals have a lower percentage of hemoglobin S and a lower MCV than persons with sickle trait without α-thalassemia.1-3We agree that lower concentrations of hemoglobin S in the sickle trait erythrocyte may be beneficial to those with α-thalassemia. However, it is important to remember that 70% of blacks with sickle cell trait do not have α-thalassemia. These individuals vastly outnumber nonblacks with sickle trait, and the percentage of hemoglobin S in their erythrocytes (40% ±0.6%)1is identical to that observed in our nonblack patients. Given these considerations, the disproportionate number of cases of altitude-induced splenic syndrome observed in nonblacks is likely due to factors other than the incidence of α-thalassemia in