A primer for predicting risk of disease in HFE-linked hemochromatosis.

Since the discovery of the hemochromatosis gene (HFE) in 1996, there has been increasing interest in diagnostic testing for the C282Y and H63D mutations. The high frequency of these two alleles and their incomplete penetrance in homozygotes and compound heterozygotes make genetic counseling for hemochromatosis different from some other autosomal recessive conditions in that parents and children may also be at risk for iron overload, while homozygotes may remain asymptomatic. We provide a guideline for genetic counseling in HFE-linked hemochromatosis based on the genetic probability of inheriting HFE mutations and known information about expression of iron overload in various HFE genotypes. Genetic probabilities were based on allele frequencies derived from large population studies and Hardy-Weinberg equilibrium estimates. Expression of iron overload in those of various genotypes was based on available estimates of serum ferritin from population screening studies. Estimates for the likelihood of clinical iron overload requiring follow-up screening or treatment are provided by gender and genotype. The probability of inheriting HFE mutations and developing iron overload can be estimated in family members of a proband with HFE mutations. Many C282Y homozygotes will not have clinical iron overload. The risk is highest in men and their C282Y homozygous brothers and significantly lower in homozygous women. Iron overload is uncommon in compound heterozygotes and H63D homozygotes.