GSTM1 and anemia (phenotype): The anemia prevalence with Hb < 12.0 g/dL was 29.42%, with 1.74% identified with severe anemia (Hb < 8.0 g/dL for ages 10–19), 11.97% had moderate anemia (Hb: 8.0–10.9 g/dL for ages 10–19), and 15.71% had mild anemia (Hb: 11.0–11.4 g/dL for ages 10–11, and Hb: 11.0–11.9 g/dL for ages 12–19).