title: A novel homozygous stop-codon mutation in human HFE responsible for nonsense-mediated mRNA decay.
abstract: HFE-hemochromatosis (HH) is an autosomal disease characterized by excessive iron absorption. Homozygotes for H63D variant, and still less H63D heterozygotes, generally do not express HH phenotype. The data collected in our previous study in the province of Matera (Basilicata, Italy) underlined that some H63D carriers showed altered iron metabolism, without additional factors. In this study, we selected a cohort of 10/22 H63D carriers with severe biochemical iron overload (BIO). Additional analysis was performed for studying HFE exons, exon-intron boundaries, and untranslated regions (UTRs) by performing DNA extraction, PCR amplification and sequencing. The results showed a novel substitution (NM_000410.3:c.847C>T) in a patient exon 4 (GenBankJQ478433); it introduces a premature stop-codon (PTC). RNA extraction and reverse-transcription were also performed. Quantitative real-time PCR was carried out for verifying if our aberrant mRNA is targeted for nonsense-mediated mRNA decay (NMD); we observed that patient HFE mRNA was expressed much less than calibrator, suggesting that the mutated HFE protein cannot play its role in iron metabolism regulation, resulting in proband BIO. Our finding is the first evidence of a variation responsible for a PTC in iron cycle genes. The genotype-phenotype correlation observed in our cases could be related to the additional mutation.
authors.affiliation: Department of Science, University of Basilicata, Viale dell'Ateneo Lucano, 85100 Potenza, Italy. Electronic address: mariacarmela.padula@unibas.it.
authors.forename: Maria Carmela
authors.initials: MC
authors.lastname: Padula
authors.affiliation: Department of Science, University of Basilicata, Viale dell'Ateneo Lucano, 85100 Potenza, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Martelli
authors.affiliation: Department of Science, University of Basilicata, Viale dell'Ateneo Lucano, 85100 Potenza, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Larocca
authors.affiliation: Department of Science, University of Basilicata, Viale dell'Ateneo Lucano, 85100 Potenza, Italy.
authors.forename: Rocco
authors.initials: R
authors.lastname: Rossano
authors.affiliation: Clinic of Hematology, Hospital-University Company "Ospedali Riuniti di Ancona", Via Conca, 60126 Ancona, Italy.
authors.forename: Attilio
authors.initials: A
authors.lastname: Olivieri
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D018389:Codon, Nonsense; D018388:Codon, Terminator; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D005293:Ferritins / Q000097:blood; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D019190:Iron Overload / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D059365:Nonsense Mediated mRNA Decay; D020641:Polymorphism, Single Nucleotide; D011487:Protein Conformation; D012189:Retrospective Studies
chemical_list: D018389:Codon, Nonsense; D018388:Codon, Terminator; C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D005293:Ferritins
keywords: HFE; Hemochromatosis; Mutations; Nonsense-mediated mRNA decay (NMD); Premature translation-termination codon (PTC)