In vitro studies showed that also BMP5, 7 and 9 can induce SMAD pathway and hepcidin expression in primary hepatocytes (Truksa et al., 2006) but after the finding that BMP6 is modulated by systemic iron and, more important, that BMP6-/- mice suffer of severe iron overload and the lack of liver hepcidin it was accepted that BMP6 is the major regulator of hepcidin expression (Andriopoulos et al., 2009; Meynard et al., 2009). Here, BMP6 is linked to Tangier disease.