GSTM1 and anemia (phenotype): In the TRACT trial, in children with severe uncomplicated anaemia (Hb 4-6g/dl) who were not randomised to receive an immediate transfusion, close clinical and Hb monitoring forde novo development of signs of severity or haemoglobin drops to < 4g/dl demonstrated that 386/787 (49%) of children developed severe and complicated anaemia, 295 of these were due to drops in the Hb < 4g/dl16.