Age versus Tf saturation and age versus serum ferritin in patients with FPN-linked hemochromatosis. Values for Tf saturation (A) and serum ferritin (B) were obtained for hemochromatosis patients with the FPN mutants indicated from the specified references. The in vitro behavior of the different FPN mutants is also shown. ^*Data for C326Y obtained by V.V., A.T.M-C., Y.C., and K.J.H.R. †We have not tested the in vitro function of C326S or N144T.