A new mutation in the hepcidin promoter impairs its BMP response and contributes to a severe phenotype in HFE related hemochromatosis

Abstract

Low levels of hepcidin are responsible for the development of iron overload in p.Cys282Tyr HFE related hemochromatosis. Every genetic factor lowering the hepcidin gene expression could contribute to a more severe phenotype in HFE hemochromatosis. Based on this hypothesis, we identified a heterozygous nc.-153 C>T mutation in the hepcidin gene promoter sequence in a patient homozygous for the p.Cys282Tyr HFE mutation who presented massive iron overload, resisting to well conducted iron depletive treatment. Our results demonstrate that the nc.-153 C>T mutation, located within a BMP-RE (Bone Morphogenetic Protein-Responsive Element): i) decreases the transcriptional activity of the hepcidin promoter, ii) alters its IL-6 (Interleukin-6) total responsiveness, and iii) prevents the binding of the SMAD protein complex (1/5/8 and 4) to the BPM-RE. In conclusion, our results suggest that a mutation in the BMP-RE of hepcidin promoter may impact on human iron metabolism.