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CYBRD1 as a modifier gene that modulates iron phenotype in HFE p.C282Y homozygous patients.

ABSTRACT: Most patients with hereditary hemochromatosis in the Caucasian population are homozygous for the p.C282Y mutation in the HFE gene. The penetrance and expression of hereditary hemochromatosis differ largely among cases of homozygous p.C282Y. Genetic factors might be involved in addition to environmental factors.In the present study, we analyzed 50 candidate genes involved in iron metabolism and evaluated the association between 214 single nucleotide polymorphisms in these genes and three phenotypic outcomes of iron overload (serum ferritin, iron removed and transferrin saturation) in a large group of 296 p.C282Y homozygous Italians. Polymorphisms were tested for genetic association with each single outcome using linear regression models adjusted for age, sex and alcohol consumption.We found a series of 17 genetic variants located in different genes with possible additive effects on the studied outcomes. In order to evaluate whether the selected polymorphisms could provide a predictive signature for adverse phenotype, we re-evaluated data by dividing patients in two extreme phenotype classes based on the three phenotypic outcomes. We found that only a small improvement in prediction could be achieved by adding genetic information to clinical data. Among the selected polymorphisms, a significant association was observed between rs3806562, located in the 5'UTR of CYBRD1, and transferrin saturation. This variant belongs to the same haplotype block that contains the CYBRD1 polymorphism rs884409, found to be associated with serum ferritin in another population of p.C282Y homozygotes, and able to modulate promoter activity. A luciferase assay indicated that rs3806562 does not have a significant functional role, suggesting that it is a genetic marker linked to the putative genetic modifier rs884409.While our results support the hypothesis that polymorphisms in genes regulating iron metabolism may modulate penetrance of HFE-hereditary hemochromatosis, with emphasis on CYBRD1, they strengthen the notion that none of these polymorphisms alone is a major modifier of the phenotype of hereditary hemochromatosis.

SUBMITTER: Pelucchi S

PROVIDER: S-EPMC3590088 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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CYBRD1 as a modifier gene that modulates iron phenotype in HFE p.C282Y homozygous patients.

Pelucchi Sara S Mariani Raffaella R Calza Stefano S Fracanzani Anna Ludovica AL Modignani Giulia Litta GL Bertola Francesca F Busti Fabiana F Trombini Paola P Fraquelli Mirella M Forni Gian Luca GL Girelli Domenico D Fargion Silvia S Specchia Claudia C Piperno Alberto A

Haematologica 20120706 12

<h4>Background</h4>Most patients with hereditary hemochromatosis in the Caucasian population are homozygous for the p.C282Y mutation in the HFE gene. The penetrance and expression of hereditary hemochromatosis differ largely among cases of homozygous p.C282Y. Genetic factors might be involved in addition to environmental factors.<h4>Design and methods</h4>In the present study, we analyzed 50 candidate genes involved in iron metabolism and evaluated the association between 214 single nucleotide p ...[more]

PMID: 22773607

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Project description:BackgroundScreening program participants with iron overload (IO) phenotypes without HFE p.C282Y/p.C282Y are incompletely characterized.MethodsWe studied white participants who had IO phenotypes without p.C282Y/p.C282Y in post-screening clinical examinations (CE). We defined IO phenotypes as a) elevated serum ferritin (SF) and transferrin saturation (TS) at screening and CE, and b) absence of IO treatment, anemia, transfusion >10 units, alcohol intake >30 g/d, hepatitis B or C, and pregnancy. We defined IO-related disease as elevated alanine or aspartate aminotransferase (ALT/AST) or swelling/tenderness of 2nd/3rd metacarpophalangeal (MCP) joints. All participants had HFE p.C282Y and p.H63D genotyping.ResultsThere were 32 men and 26 women (mean age 54±16 y). Median food/supplemental iron intakes were 14.3/0.0 mg/d. Relative risks of HFE genotypes were 12.9 (p.C282Y/p.H63D), 3.0 (p.H63D/p.H63D), 1.9 (p.C282Y/wt), 0.9 (p.H63D/wt), and 0.5 (wt/wt) compared to 42,640 white screening participants without IO phenotypes or p.C282Y/p.C282Y. Regression on SF revealed positive associations: MCV (p = 0.0006; β coefficient = 0.4531); swelling/tenderness of MCP joints (p = 0.0033; β = 0.3455); and p.H63D/wt (p = 0.0015; β = 0.4146). IO-related disease (18 elevated ALT/AST, one swelling/tenderness of MCP joints) occurred in 19 participants (7 men, 12 women). Median MCV was higher in participants with IO-related disease (97 fL vs. 94 fL; p = 0.0007). Logistic regression on IO-related disease revealed a significant association with diabetes (p = 0.0416; odds ratio 18.9 (95% confidence interval 1.0, 341.1)).ConclusionsIn the present 58 screening program participants who had IO phenotypes without HFE p.C282Y/p.C282Y, relative risks of HFE genotypes p.C282Y/p.H63D, p.H63D/p.H63D, and p.C282Y/wt were significantly higher than in 42,640 white screening participants with neither IO phenotypes nor p.C282Y/p.C282Y. SF was significantly associated with MCV, swelling/tenderness of 2nd/3rd MCP joints, and p.H63D/wt. IO-related disease was significantly associated with MCV and diabetes.

Project description:ImportanceHereditary hemochromatosis is predominantly caused by the HFE p.C282Y homozygous pathogenic variant. Liver carcinoma and mortality risks are increased in individuals with clinically diagnosed hereditary hemochromatosis, but risks are unclear in mostly undiagnosed p.C282Y homozygotes identified in community genotyping.ObjectiveTo estimate the incidence of primary hepatic carcinoma and death by HFE variant status.Design, setting, and participantsCohort study of 451 186 UK Biobank participants of European ancestry (aged 40-70 years), followed up from baseline assessment (2006-2010) until January 2018.ExposuresMen and women with HFE p.C282Y and p.H63D genotypes compared with those with neither HFE variants.Main outcomes and measuresTwo linked co-primary outcomes (incident primary liver carcinoma and death from any cause) were ascertained from follow-up via hospital inpatient records, national cancer registry, and death certificate records, and from primary care data among a subset of participants for whom data were available. Associations between genotype and outcomes were tested using Cox regression adjusted for age, assessment center, genotyping array, and population genetics substructure. Kaplan-Meier lifetable probabilities of incident diagnoses were estimated from age 40 to 75 years by HFE genotype and sex.ResultsA total of 451 186 participants (mean [SD] age, 56.8 [8.0] years; 54.3% women) were followed up for a median (interquartile range) of 8.9 (8.3-9.5) years. Among the 1294 male p.C282Y homozygotes, there were 21 incident hepatic malignancies, 10 of which were in participants without a diagnosis of hemochromatosis at baseline. p.C282Y homozygous men had a higher risk of hepatic malignancies (hazard ratio [HR], 10.5 [95% CI, 6.6-16.7]; P < .001) and all-cause mortality (n = 88; HR, 1.2 [95% CI, 1.0-1.5]; P = .046) compared with men with neither HFE variant. In lifetables projections for male p.C282Y homozygotes to age 75 years, the risk of primary hepatic malignancy was 7.2% (95% CI, 3.9%-13.1%), compared with 0.6% (95% CI, 0.4%-0.7%) for men with neither variant, and the risk of death was 19.5% (95% CI, 15.8%-24.0%), compared with 15.1% (95% CI, 14.7%-15.5%) among men with neither variant. Among female p.C282Y homozygotes (n = 1596), there were 3 incident hepatic malignancies and 60 deaths, but the associations between homozygosity and hepatic malignancy (HR, 2.1 [95% CI, 0.7-6.5]; P = .22) and death (HR, 1.2 [95% CI, 0.9-1.5]; P = .20) were not statistically significant.Conclusions and relevanceAmong men with HFE p.C282Y homozygosity, there was a significantly increased risk of incident primary hepatic malignancy and death compared with men without p.C282Y or p.H63D variants; there was not a significant association for women. Further research is needed to understand the effects of early diagnosis and treatment.

Project description:IntroductionHFE p.C282Y homozygosity is the most common cause of hereditary haemochromatosis. There is currently insufficient evidence to assess whether non-specific symptoms or hepatic injury in homozygotes with moderately elevated iron defined as a serum ferritin (SF) of 300-1000 µg/L are related to iron overload. As such the evidence for intervention in this group is lacking. We present here methods for a study that aims to evaluate whether non-specific symptoms and hepatic fibrosis markers improve with short-term normalisation of SF in p.C282Y homozygotes with moderate elevation of SF.Methods and analysisMi-iron is a prospective, multicentre, randomised patient-blinded trial conducted in three centres in Victoria and Queensland, Australia. Participants who are HFE p.C282Y homozygotes with SF levels between 300 and 1000 μg/L are recruited and randomised to either the treatment group or to the sham treatment group. Those in the treatment group have normalisation of SF by 3-weekly erythrocytapheresis while those in the sham treatment group have 3-weekly plasmapheresis and thus do not have normalisation of SF. Patients are blinded to all procedures. All outcome measures are administered prior to and following the course of treatment/sham treatment. Patient reported outcome measures are the Modified Fatigue Impact Scale (MFIS-primary outcome), Hospital Anxiety and Depression Scale (HADS), Medical Outcomes Study 36-item short form V.2 (SF36v2) and Arthritis Impact Measurement Scale 2 short form (AIMS2-SF). Liver injury and hepatic fibrosis are assessed with transient elastography (TE), Fibrometer and Hepascore, while oxidative stress is assessed by measurement of urine and serum F2-isoprostanes.Ethics and disseminationThis study has been approved by the Human Research Ethics Committees of Austin Health, Royal Melbourne Hospital and Royal Brisbane and Women's Hospital. Study findings will be disseminated through peer-reviewed publications and conference presentations.Trial registrationTrial identifier: NCT01631708; Registry: ClinicalTrials.gov.

Dataset Information

CYBRD1 as a modifier gene that modulates iron phenotype in HFE p.C282Y homozygous patients.

Publications

CYBRD1 as a modifier gene that modulates iron phenotype in HFE p.C282Y homozygous patients.

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