GSTM1 and anemia (phenotype): All children with thalassaemia disease were anaemic, and three fourths of the children with α0-thalassaemia trait, β-thalassaemia trait and homozygous Hb E were anaemic compared with an anaemia prevalence of 46.8 % among children without clinically significant IHbD (P < 0.001; Table 3).