GSTM1 and endothelial dysfunction: RBCs clearance and extracellular Hb scavenging are relatively modest events under steady-state conditions, but are drastically enhanced in hemolytic disorders (e.g., anemia, vasculopathy, endothelial dysfunction, and infections), when high levels of extracellular Hb and heme ultimately lead to the saturation and depletion of Hp and Hx scavenging systems [24], causing heme-mediated oxidative damage to tissues [1,2,25].