7, 8 H2O2 produced by the pneumococcus oxidizes oxy-hemoglobin (Fe2+) from different mammals, including humans, to produce the non-oxygen-binding form of hemoglobin known as met-hemoglobin (Hb-Fe3+).9, 10 The oxidation of hemoglobin by Spn produced toxic species, including labile heme11 and a hemoglobin-derived tyrosyl radical [Fig. 1A, (•Hb-Fe4+)].12 These toxic products are implicated in the pathophysiology of human diseases characterized by intravascular hemolysis, such as sickle cell disease (SCD), and in inflammatory conditions, such as sepsis.13, 14, 15. The gene discussed is GSTM1; the disease is sickle cell disease.