The importance of the HAMP/FPN axis is illustrated by diseases of systemic iron overload such as hemochromatosis and β-thalassaemia, where hepcidin production is impaired (Camaschella, 2005; Musallam et al., 2012), and in anaemia of chronic disease where hepcidin production is inappropriately elevated (De Falco et al., 2013; Nemeth and Ganz, 2014). Here, HAMP is linked to anemia (phenotype).