Df. Wallace et al., A novel mutation of HFE explains the classical phenotype of genetic hemochromatosis in a C282Y heterozygote, GASTROENTY, 116(6), 1999, pp. 1409-1412
Background & Aims: Most patients with genetic hemochromatosis are homozygou
s 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 s
tudy was to investigate the basis of iron overload in a patient with classi
cal hemochromatosis who was only heterozygous for C282Y and negative for H6
3D. Methods: Genotype for the C282Y, H63D, and S65C mutations of HFE was de
termined in patient RFH, his family members, and 365 controls. The HFE gene
was sequenced in patient RFH. Allele-specific reverse-transcription polyme
rase chain reaction was performed to investigate RNA splicing. Allele frequ
ency was determined by allele-specific oligonucleotide hybridization. Resul
ts: The patient is compound heterozygous for C282Y and a novel splice site
mutation (IVS3 + 1G --> T). His sister has an identical genotype and elevat
ed serum ferritin and transferrin saturation. The novel mutation functional
ly alters messenger RNA splicing, causing obligate skipping of exon 3. Howe
ver, 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 c
ompound heterozygous state with C282Y results in iron overload that can pro
gress 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.