Complete Characterization of the 3′ Region of the Human and Mouse Hereditary Hemochromatosis HFE Gene and Detection of Novel Splicing Forms,,

The human HFE gene was identified in 1996 as the gene whose mutations are responsible for hereditary hemochromatosis in most patients. Expression analysis by Northern blot indicated that the gene was approximately 4.1 kb in length. However, the cDNA reported was only 2716 bp. These results implied that at least 1.4 kb of the mRNA remained to be identified. In the present study, we detected several 3′ EST clones while screening the genomic region of the gene in search of potential additional HFE mRNA sequences. Subsequent sequencing of these EST clones and RT-PCR experiments revealed that exon 7 of the HFE gene has, in fact, a length of 1944 bp and it presents two polyadenylation signals. The new human HFE exon 7 region has been screened in non-C282Y HH patients in search for new putative mutations. Mouse 3′ RACE experiments also further extend the previously reported mouse HFE exon 6 sequence. Additionally, we report two novel end forms of the human HFE gene detected by 3′ RACE experiments and several novel splicing forms identified in the HepG2 cell line.