Since JBS Haldane first speculated that red blood cell (RBC) variants may confer some resistance to malaria, numerous studies using diverse approaches have identified an array of innate variants, which can be grouped as disorders of the erythrocyte cytoskeleton (e.g., Southeast Asian ovalocytosis), variation in erythrocyte surface antigens (e.g., ABO and Duffy), enzymatic aberrations (e.g., glucose-6-phosphate dehydrogenase deficiency), and mutants of α- or β-globin proteins, either as deletions (e.g., α-thalassemia) or point mutations (e.g., hemoglobin [Hb] S or C). The gene discussed is GSTM1; the disease is thalassemia.