GSTM1 and paroxysmal nocturnal hemoglobinuria: In diseases associated with systemic hemolysis, such as paroxysmal nocturnal hemoglobinuria and hemolytic uremic syndrome, or in aggressive forms of glomerular injury in which hemoglobinuria owing to erythrocyte injury/lysis within glomerular capillaries is a prominent feature, cells comprising the glomerular microvasculature (endothelial cells, mesangial cells, and podocytes) are exposed to high concentrations of free/labile heme released from of hemoglobin (Hb).