GSTM1 and anemia (phenotype): Anaemia was defined using the WHO age-specific cut off points for Hb (< 11.5 g/dL for children 6 to < 12 years of age, < 12.0 g/dL for those 12–14 years of age, < 13 g/dL and < 12 g/dL for male and female children aged 15 years, respectively) [37, 38].