Furthermore, cerebral oxygen saturation was lower in patients with anemia than those without anemia (with anemia: Hb level 8.7 ± 2.3 g/dL, cerebral rSO2: 50 ± 11%; without anemia: Hb level 12.3 ± 4.2 g/dL, cerebral rSO2: 66 ± 8%) [26]. This evidence concerns the gene GSTM1 and anemia.