SLC30A10 Deficiency: A Novel Cause of Polycythemia and Hepcidin Deficiency

Like iron, manganese is an essential yet potentially toxic metal. While inherited forms of iron excess were discovered long ago, the first disease of inherited manganese excess was only recently reported in 2012. Mutations in a metal transport protein, SLC30A10, were described in patients with manganese excess, polycythemia, liver failure and Parkinsonism. Manganese excess in these patients is attributed to an essential role for SLC30A10 in hepatobiliary manganese excretion. Polycythemia, liver failure and Parkinsonism are attributed to manganese excess although the underlying mechanisms have yet to be established. To explore the role of SLC30A10 in metal biology and disease, we have generated Slc30a10-deficient mice. Characterization of these mice indicates that murine Slc30a10 deficiency recapitulates the human disease. Given that manganese and iron share some transport pathways, we interrogated iron homeostasis in these mutant mice. Intriguingly, mice display hepcidin deficiency and tissue iron excess. While hepcidin deficiency may explain the tissue iron excess, the cause of hepcidin deficiency is unclear. Based on expression profiling of hypoxia-regulated genes, we propose that hepcidin deficiency reflects aberrant activation of hypoxia signaling by manganese excess in the absence of true hypoxia. Overall, this data suggests novel interactions between iron and manganese with implications for our understanding of the mechanisms by which aberrant metal homeostasis leads to human disease.