Some studies13,14 have reported that anemia was frequently accompanied by depressive symptoms in older adults, while a meta-analysis has shown a positive association between anemia and depression in adults and maternal populations.15 In a case-control study, individuals with depression were found to have lower hemoglobin (Hb) levels.16 However, other studies have not reported conclusive evidence supporting the link between anemia and depression.17,18 Therefore, whether anemia is a risk factor for depression needs further elucidation. Here, GSTM1 is linked to anemia (phenotype).