Based on the imputed data, mild anaemia (Hb between 80 and 120 g/l) was present in 27 % of HUU and 28 % of HEU children and severe anaemia (Hb < 80 g/l) was present in 5 % of HUU and 2 % of HEU children (χ2P = 0·001). Here, GSTM1 is linked to anemia (phenotype).