GSTM1 and anemia (phenotype): When exploring associations of Hb and anemia with other iron indicators, we found that Hb had positive associations with serum iron (coef: 0.33, 95% CI: 0.16, 0.49, p < 0.0001, second in dominance) and hepcidin (coef: 0.17, 95% CI: 0.02, 0.31; p = 0.023; sixth in dominance) and a negative association with sTfR (coef: −0.55, 95% CI: −0.92, −0.18; p = 0.004; fourth in dominance) (Supplementary Table S1B–D).