title: Contribution of different HFE genotypes to iron overload disease: a pooled analysis.
abstract: OBJECTIVE
  To determine the contribution of the C282Y and H63D mutations in the HFE gene to clinical expression of hereditary hemochromatosis.
  
  
  METHODS
  Pooled analysis of 14 case-control studies reporting HFE genotype data, to evaluate the association of different HFE genotypes with iron overload. In addition, we used data from the pooled analysis and published data to estimate the penetrance of the C282Y/C282Y genotype.
  
  
  RESULTS
  Homozygosity for the C282Y mutation carried the largest risk for iron overload (OR = 4383, 95% CI 1374 to >10,000) and accounted for the majority of hemochromatosis cases (attributable fraction (AF) = 0.73). Risks for other genotypes were much smaller: OR = 32 for genotype C282Y/H63D (95% CI 18.5 to 55.4, AF = 0.06); OR = 5.7 for H63D/H63D (95% CI 3.2 to 10.1, AF = 0.01); OR = 4.1 for C282Y heterozygosity (95% CI 2.9 to 5.8, with heterogeneity in study results, making this association uncertain); and OR = 1.6 for H63D heterozygosity (95% CI 1 to 2.6, AF = 0.03). Estimates of penetrance for the C282Y/C282Y genotype were highly sensitive to estimates of the prevalence of iron overload disease. At a prevalence of 2.5 per 1000 or less, penetrance of the C282Y/C282Y genotype is unlikely to exceed 50%. Penetrance of other HFE genotypes is much lower.
  
  
  CONCLUSIONS
  C282Y homozygosity confers the highest risk for iron overload but the H63D mutation is also associated with increased risk. Our data indicate a gradient of risk associated with different HFE genotypes and thus suggest the presence of other modifiers, either genetic or environmental, that contribute to the clinical expression of hemochromatosis.
authors.affiliation: Department of Medical History and Ethics, University of Washington, Seattle, Washington 98195, USA. wburke@u.washington.edu.
authors.forename: W
authors.initials: W
authors.lastname: Burke
authors.forename: G
authors.initials: G
authors.lastname: Imperatore
authors.forename: S M
authors.initials: SM
authors.lastname: McDonnell
authors.forename: R C
authors.initials: RC
authors.lastname: Baron
authors.forename: M J
authors.initials: MJ
authors.lastname: Khoury
mesh_terms: D019943:Amino Acid Substitution; D016022:Case-Control Studies; D000071020:Hemochromatosis Protein; D006579:Heterozygote; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D019190:Iron Overload / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D020125:Mutation, Missense; D019683:Penetrance; D012307:Risk Factors
chemical_list: C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins