Two novel nonsense mutations of HFE gene in five unrelated italian patients with hemochromatosis.

BACKGROUND & AIMS: Most hemochromatosis patients of Northern European descent are homozygous for the C282Y mutation of HFE gene. In Italy, many patients with iron overload are not homozygous for C282Y, and the presence of other mutations or other genetic determinant has been suggested. METHODS: Five unrelated Italian patients heterozygous for C282Y with the classic hemochromatosis phenotype were studied. The entire coding sequence and the exon-intron boundaries of the HFE gene were analyzed. Chromosome 6p haplotypes were defined in each patient by analysis of D6S265, D6S105, and D6S1281 microsatellites. RESULTS: Two novel nonsense HFE mutations were identified in exon 3 in the C282Y negative chromosome. The first one, a G-to-T transition at codon 168, was detected in 3 probands; the second, a G-to-A transition at codon 169, was detected in the others. CONCLUSIONS: The 2 nonsense mutations in the compound heterozygous state with C282Y result in the classic hemochromatosis phenotype in several unrelated Italian patients. This confirms that hemochromatosis in Italy is not as homogeneous as in northern Europe and suggests that other mutations can exist in C282Y or H63D heterozygotes with iron overload. These findings have practical implications for diagnostic and screening strategies for hemochromatosis.