Transferrin receptor 2 (TFR2) is highly expressed in liver and erythroid precursor cells and is a close homologue of human transferrin receptor 1 (TFRC). Transferrin (TF), loaded with iron (holoTF), transports two ferric iron ions through the blood. Two holoTFs bind to a TFR2 dimer (with lower affinity than to TFRC) and mediates cellular uptake of holoTF in a non-iron dependent manner (Kawabata et al. 1999, Trinder & Baker 2003). Defects in TFR2 can cause hemochromatosis 3 (HFE3; MIM:604250), an iron metabolism disorder characterised by iron overload. Excess iron is deposited over decades in a variety of organs leading to their failure, resulting in serious illnesses including cirrhosis, hepatomas, diabetes, cardiomyopathy, arthritis and hypogonadotropic hypogonadism (Camaschella et al. 2000, Wallace & Subramaniam 2007).