The major diagnostic criteria for PRCA due to anti-epoetin antibodies include treatment with epoetin for at least 3 weeks, a red blood cell transfusion requirement of approximately 1 unit per week to keep hemoglobin levels stable, reticulocyte count less than 10 × 109/L and no major drop in white blood cell or platelet counts. This evidence concerns the gene EPO and pure red-cell aplasia.