The most frequently reported primary clinical consideration for prescribing a PRBC transfusion was anemia symptoms (106 [72.1%] patients; mean Hb, 8.1 g/dL), followed by Hb value (37 [25.2%] patients; mean Hb, 8.1 g/dL) and medical history (4 [2.7%] patients; mean Hb, 8.5 g/dL). The gene discussed is GSTM1; the disease is anemia.