TMPRSS6 and hemochromatosis: HH is caused by multiple genetic defects like HFE, TfR2, HJV, TMPRSS6, FPN1, and HAMP. According to different mutant genes, HH is divided into HFE hemochromatosis (type1), juvenile hemochromatosis (type 2), TfR2 hemochromatosis (type 3), and ferroportin hemochromatosis.