GNPAT rs11558492 is not a major modifier of iron status : study of Italian hemochromatosis patients and blood donors

Background and Aim. HFE-related Hemochromatosis (HH) is characterized by marked phenotype heterogeneity, probably due to the combined action of acquired and genetic factors. Among them, GNPAT rs11558492 was proposed as genetic modifier of iron status, but results are still controversial. To shed light on these discrepancies, we genotyped 298 Italian p.C282Y homozygotes and 169 healthy controls. Material and methods. Allele and genotype frequencies were analysed and compared with those reported in Exome Variant Server (EVS). To explore the role of rs11558492 as a potential modifier of iron status, serum ferritin (SF), liver iron concentration (LIC) and iron removed (IR) were studied according to allele and genotype frequencies. In addition, the effect of the SNP on liver fibrosis was examined comparing patients with absent/mild-moderate fibrosis to those with severe fibrosis-cirrhosis. Results. GNPAT rs11558492 minor allele (G) frequency (MAF) was 20.3% in HFE-HH, 17.2% in controls and 20.6% in EVS database. Genotype frequencies were 64% and 69.2% (AA), 31.2% and 27.2% (AG), 4.8% and 3.6% (GG) in HFE-HH and controls, respectively. No significant differences were found comparing genotype and allele frequencies even selecting subgroups of only-males with extreme phenotypes and low alcohol intake. SF, IR and LIC levels did not significantly differ according to rs11558492 genotypes. Also, MAF did not differ between patients with absent/mild fibrosis and severe fibrosis/cirrhosis. Conclusions. Our findings indicate that GNPAT rs11558492 is not a major modifier of iron status and is not associated with liver fibrosis in HFE-HH patients