Linkage to chromosome 1q in Greek families with juvenile hemochromatosis

Hereditary hemochromatosis (HH) is a genetically heterogeneous disease. The HFE gene resides on chromosome 6 and its mutations account for the majorit y of HH cases in populations of northern European ancestry. Recently, two n ew types of hemochromatosis have been identified: Juvenile hemochromatosis (JH or HFE2), which maps to chromosome 1q21, and an adult form defined as H FE 3, which results from mutations of the TFR 2 gene, located at 7q22. We h ave performed a linkage study in five unrelated families of Greek origin wi th non-HFE hemochromatosis. Linkage at the chromosome 1q21 JH locus was det ected in affected members with the use of polymorphic markers. Comparison o f haplotypes between Greek and Italian JH patients revealed the presence of a common haplotype. However, the fact that many other haplotypes carrying the JH defect were observed in the two populations indicates that the respe ctive mutations may have occurred in different genetic backgrounds. We sugg est 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 on set in some cases. (C) 2001 Academic Press.