Further, when the children were disaggregated by age, the authors found a larger and statistically significant effect in younger children aged 3–5.9 months, with a 7.6 g/L (P = 0.02) increase in Hb concentration and a 14.6% (P = 0.02) reduction in anaemia prevalence (Olney et al., 2015). Here, GSTM1 is linked to anemia (phenotype).