Ablation of ERFE in thalassemic mice restores WT hepcidin levels.Th3/+ mice had significantly lower hepcidin mRNA levels at 3 and 6 weeks of age compared with WT mice. Erfe-deficient mice on a thalassemic background (Erfe^−/−, Th3/+) had similar hepcidin to WT mice at 3 and 6 weeks of age. Erfe^+/−, Th3/+ mice also showed greatly elevated hepcidin compared with Th3/+ mice at the age of 6 weeks. No difference was observed between the 12-week-old mice. Data shown are means ± SEM and were compared for each age group among WT, Th3/+, Erfe^+/−, Th3/+, and Erfe^−/−, Th3/+ mice (n = 9 to 36 per group) by 2-tailed Student t-test. ***P < .001, **P < .01, *P < .05.