A novel mutation of HFE explains the classical phenotype of genetic hemochromatosis in a C282Y heterozygote.
OBJECTIVE
Most patients with genetic hemochromatosis are homozygous for a single mutation of the HFE gene (C282Y). There is a second mutation, H63D, but its role in iron overload is less conclusive. The aim of this study was to investigate the basis of iron overload in a patient with classical hemochromatosis who was only heterozygous for C282Y and negative for H63D.


METHODS
Genotype for the C282Y, H63D, and S65C mutations of HFE was determined in patient RFH, his family members, and 365 controls. The HFE gene was sequenced in patient RFH. Allele-specific reverse-transcription polymerase chain reaction was performed to investigate RNA splicing. Allele frequency was determined by allele-specific oligonucleotide hybridization.


RESULTS
The patient is compound heterozygous for C282Y and a novel splice site mutation (IVS3 + 1G --> T). His sister has an identical genotype and elevated serum ferritin and transferrin saturation. The novel mutation functionally alters messenger RNA splicing, causing obligate skipping of exon 3. However, the IVS3 + 1G --> T mutation was found to be rare and was not detected in 630 control European chromosomes.


CONCLUSIONS
IVS3 + 1G --> T in the compound heterozygous state with C282Y results in iron overload that can progress to a severe phenotype of classical hemochromatosis. The demonstration of IVS3 +1G --> T highlights the possibility of other rare HFE mutations, particularly in C282Y heterozygotes with iron overload.
Wallace
D F
DF
Centre for Hepatology, Department of Medicine, Royal Free and University College Medical School, University College London, Royal Free Campus, London, England.
Dooley
J S
JS
Walker
A P
AP
D000328:Adult; D004274:DNA, Recombinant; D005260:Female; D005787:Gene Frequency; D006680:HLA Antigens / Q000235:genetics*; D006432:Hemochromatosis / Q000235:genetics*; D000071020:Hemochromatosis Protein; D006579:Heterozygote; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics
D004274:DNA, Recombinant; C103673:HFE protein, human; D006680:HLA Antigens; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D012333:RNA, Messenger