GSTM1 and hemoglobinopathy: Four cases (Table 2, numbers 1–4) showed normal Hb levels with high HbF and were described as hereditary persistence of fetal Hb (HPFH) (Satta et al., 2011; Radmilovic et al., 2013; Rani et al., 2018), a kind of benign hemoglobinopathy.