Our objective was to assess the iron indexes of patients with one or more mutations of the HFE gene with a specific interest in studying the effect of the H63D/H63D genotype. Eight hundred twenty subjects who underwent HFE mutational testing for C282Y and H63D mutations were retrospectively identified. Data collected included age, gender, HFE genotype, and values for serum ferritin, iron saturation, aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Compared to the Wild/Wild genotype (0.34 +/- 0.17), genotypes H63D/C282Y (0.44 +/- 0.14 P < 0.01), H63D/H63D (0.51 +/- 0.21 P < 0.01), and C282Y/C282Y (0.64 +/- 0.20 P < 0.01) had significantly higher transferrin saturation levels and were independent predictors of higher iron saturation in multivariate regression analysis. Compared to the Wild/Wild genotype, no abnormal HFE genotypes had significantly higher ferritin levels, although the genotype H63D/H63D was an independent predictor of higher serum ferritin (P = 0.02) in regression analysis. There was no significant difference in the proportion of patients with abnormally elevated AST (P = 0.64) or ALT (P = 0.80) between groups. H63D homozygotes have elevated transferrin saturation compared to the Wild genotype, comparable to that of C282Y homozygotes and compound heterozygotes. The clinical significance of this finding is unclear but warrants further study.