Correlations between hepcidin and sTfR and GDF15 in patients with either (A) severe or (B) moderate HbE β-thalassemia. Scatter plots show individual data points for log hepcidin against either log sTfR or log GDF15. Hepcidin is inversely correlated with sTfR and GDF15 in patients with severe clinical phenotype, but there is no significant correlation among patients with moderate disease (despite the 2 patient groups carrying similar or identical β-globin gene mutations). P values indicate significance in the correlation. ns, not significant.