Iron overload is rare in patients homozygous for the H63D mutation

Previous research has suggested that the H63D HFE mutation is associated with elevated iron indexes. However, the true penetrance of this mutation remains unclear.

To assess the proportion of H63D homozygotes with laboratory abnormalities consistent with iron overload.

The present study was a retrospective analysis of all individuals referred for HFE genotyping in Newfoundland and Labrador between 1999 and 2009, who were found to be homozygous for the H63D mutation. Using electronic health records, results of ferritin, transferrin saturation, aspartate aminotransferase and alanine aminotransferase testing performed closest to the time of genetic testing were recorded for each patient. Iron overload was classified using previously published definitions from the HealthIron study. SPSS version 17.0 (IBM Corporation, USA) was used for descriptive statistics and to compare means using one-way ANOVA.

Between 1999 and 2009, 170 individuals tested positive for H63D⁄H63D. At the time of genotyping, 28.8% had an elevated mean (± SD) ferritin level of 501±829 μg⁄L and 15.9% had an elevated transferrin saturation of 0.45±0.18. At genotyping, 94 individuals had sufficient data available to classify iron overload status. Only three (3.2%) had documented iron overload while the majority (85.1%) had no evidence of iron overload. Sixty individuals had follow-up data available and, of these, only four (6.7%) had documented iron overload, while 45 (75.0%) had no evidence of iron overload. Only one individual had evidence of iron overload-related disease at genotyping and at follow-up.

H63D homozygosity was associated with an elevated mean ferritin level, but only 6.7% had documented iron overload at follow-up. The penetrance of the H63D mutation appeared to be low.