(3) Clostridium difficile toxin B was detected by PCR, (4) normal genetic testing for HFE (human hemochromatosis protein gene) mutation excluding hemochromatosis, negative flow cytometry for PNH (paroxysmal nocturnal hemoglobinuria), a normal glucose-6-phosphate dehydrogenase screen (excluding hemolysis secondary to G6PD deficiency anemia), and (5) transesophageal echocardiogram which showed that the prosthetic mitral valve is functioning well without evidence of paravalvular leak or mitral valve regurgitation. The gene discussed is G6PD; the disease is hemochromatosis.