Brief Report: Sickle Cell Disease in a Patient with Sickle Cell Trait and Compound Heterozygosity for Hemoglobin S and Hemoglobin Quebec-Chori

THE sickle cell trait is generally considered to be benign, because the presence of hemoglobin A in a concentration of more than 50 percent in the red cells of persons heterozygotic for hemoglobin A and hemoglobin S (hemoglobin A/S) prevents the polymerization of the remaining hemoglobin S under physiologic conditions.1 Occasional reports suggest, however, that after extreme physical stress or hypoxia, the sickle cell trait can be associated with serious morbidity and even death.2- 4 In most cases, the diagnosis of this trait is straightforward: hematologic measures such as hemoglobin, hematocrit, red-cell indexes, and the reticulocyte count are normal, and electrophoretic techniques demonstrate the presence of hemoglobin A and hemoglobin S. A solubility test is used to confirm that the hemoglobin migrating in the "S" position is sickle hemoglobin. Since electrophoretic techniques separate hemoglobins on the basis of their net charge, any variant that has a net charge similar to that of either hemoglobin A or hemoglobin S will not be identified. The patient was a young child who was initially thought to have sickle cell trait on the basis of standard electrophoretic criteria. Because the child had mild anemia, symptoms consistent with vaso-occlusive episodes, and functional asplenia, further studies were undertaken. The father was not available for study. Since the most recent admission to the hospital, the patient has had several apparent vaso-occlusive crises associated with diffuse bone pain. [...]this case demonstrates the need to evaluate carefully any person with sickle cell trait who has clinical symptoms suggestive of sickle cell disease and specifically to exclude the possibility of an electrophoretically silent hemoglobin variant.