GSTM1 and anemia (phenotype): The anemia subgroups were: none/normal (Hb ≥ 12.5 g/dL), mild (10 ≤ Hb < 12.5), moderate (9 ≤ Hb < 10), severe (8 ≤ Hb < 9), or very severe (Hb < 8).