GSTM1 and anemia (phenotype): A good proportion of children had either mild (Haemoglobin (Hb) concentration 10.0–10.9 g/dl) or moderate (Hb concentration 7.0–9.9 g/dl) anaemia over the study period, and only three cases of severe anaemia (Hb concentration <7.0 g/dl) were identified, occurring in September and November 2004 (Table 1).