Higuchi et al. showed that five patients receiving Cu-free enteral nutrition developed anaemia and neutropenia despite a dose of 9000 UI erythropoietin per week due to very low Cu and ceruloplasmin levels (Cu levels in these patients ranged from 7 to 10 μg/dL and ceruloplasmin levels ranged from 2.7 to 3.6 mg/dL). This evidence concerns the gene EPO and anemia (phenotype).