Genetic factors influencing ferritin levels in 14,126 blood donors: Results from the Danish Blood Donor Study

BACKGROUND Many biologic functions depend on sufficient iron levels, and iron deficiency is especially common among blood donors. Genetic variants associated with iron levels have been identified, but the impact of genetic variation on iron levels among blood donors remains unclear. STUDY DESIGN AND METHODS The effect of six single-nucleotide polymorphisms (SNPs) on ferritin levels in 14,126 blood donors were investigated in four genes: in Human Hemochromatosis Protein gene (HFE; rs1800562 and rs179945); in Transmembrane Protease gene, Serine 6 (TMPRSS6-regulating hepcidin; rs855791); in BTB domain containing protein gene (BTBD9 - associated with restless legs syndrome; rs9357271); and in the Transferrin gene (TF; rs2280673 and rs1830084). Multiple linear and logistic regression analyses were used to evaluate the effect of each SNP on ferritin levels and the risk of iron deficiency (ferritin < 15 ng/mL). RESULTS In HFE, the G-allele of rs1800562 was associated with lower iron stores in both sexes. This was also true for the C-allele of rs179945, but in men only. Also, the T-allele of TMPRSS6 rs855791 was negatively associated with iron stores in men. Homozygocity for C in rs1799945 was associated with iron deficiency in women. Results for all other genetic variants were insignificant. CONCLUSION Genetic variants associated with hemochromatosis may protect donors against depleted iron stores. In addition, we showed that presence of the T-allele at rs855791 in TMPRSS6 was associated with lower iron stores in men.