Hereditary Hemochromatosis Manifesting After Treatment of Paroxysmal Nocturnal Hemoglobinuria With Eculizumab.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal hematopoietic stem cell disorder caused by an acquired somatic mutation in one of the genes required for synthesis of glycosylphosphatidylinositol (GPI), an anchoring protein.1-8 GPI binds several proteins to the cell, including CD55 and CD59, which inhibit cellular destruction by the alternate complement pathway. Without these proteins, PNH erythrocytes are susceptible to hemolysis via the membrane attack complex.1-8 The degree of hemolysis in PNH often exceeds the haptoglobin binding capacity of the plasma, resulting in hemoglobinuria.