Compared to patients with >20%Arg1, those with ≤20%Arg1 include patients with higher serum EPO levels (12.6 vs. 14.6 mU/ml), lower hematocrit (39% vs. 44%), lower serum hemoglobin (12.4 g/dl vs. 14.1 g/dl) and thus a higher number of patients with anemia (44% vs. 19%). Here, EPO is linked to anemia (phenotype).