Five major categories are now established: HFE-related or type1 hemochromatosis, frequently found in Caucasians, and four rarer diseases which are type 2 (A and B) hemochromatosis (juvenile hemochromatosis), type 3 hemochromatosis (transferrin receptor 2 hemochromatosis), type 4 (A and B) hemochromatosis (ferroportin disease), and a(hypo)ceruloplasminemia.
By contrast, the frequencies of the common H63D mutation did not differ, and the allele frequencies of the less frequently observed sequence deviations as substitution S65C in the HFE gene and mutation Y250X in the TFR2 gene underlying hemochromatosis type 3 (HFE3) were < 0.02 both in PCT patients and controls.
A rare recessive disorder which leads to iron overload and severe clinical complications similar to those reported in HFE-related hemochromatosis has been delineated and sometimes called hemochromatosis type 3.
We suggest that hemochromatosis patients without HFE mutations should be evaluated for other possible types of hemochromatosis since hemochromatosis type 3 (HFE3) has a clinical appearance similar to HFE 1, and JH may have a late onset in some cases.