GSTM1 and anemia: BCL11A: The primary variant tagging this locus, rs1427407, was strongly associated with HbF levels (β = 0.47, p = 7 x 10−10) and also showed a marked influence on anaemia: median [Hb] was 8.2 g/dL for GG genotype patients, 8.6 g/dL for the GT genotype, and 8.9 g/dL for the TT genotype [p = 0.011] (Fig 2).