Our finding that serum hepcidin-25, but not MCV, is a predictor of serum ferritin levels in HD patients may be explained by the fact that an alteration of serum hepcidin-25 or ferritin occurs more rapidly than changes in MCV, since prolonged iron-deficient erythropoiesis is needed to change MCV [6]. Here, HAMP is linked to Huntington disease.