Anaemia was common, with a mean Hb level of 7.40 g dL−1 (s.d., 1.55 g dL−1) and a mean erythrocyte count of 3.03 × 106 μL−1 (s.d., 0.81 × 106 μL−1). Here, GSTM1 is linked to anemia (phenotype).