GSTM1 and anemia (phenotype): The findings of greater association with anemia of two α-globin gene defects (OR: 34.0, 95%CI: 8.6–139.3) and homozygous Hb E (OR: 13.9, 95%CI: 3.5–55.7) (Table 4) agreed with the findings in previous studies conducted among pregnant women, and women of reproductive age in northeast Thailand6,12.