The diagnosis of AIHA (in CLL patients) usually requires the presence of the following criteria [5,6]: hemoglobin (Hb) levels below 11 g/dL without other explainable etiology or recent cytotoxic therapy; evidence of hemolysis by one or more laboratory markers (high reticulocyte count, consumed serum haptoglobin levels, elevated lactate dehydrogenase (LDH), or unconjugated bilirubin levels); evidence of a positive direct antiglobulin test (DAT) for either IgG or C3 or the presence of cold agglutinins. The gene discussed is GSTM1; the disease is autoimmune hemolytic anemia.