Methylation of ^Gγ-globin promoter in CD71⁺ NRBCs. (A) CpG sites −54, −51, +5, +16, and +48 of the ^Gγ-promoter are methylated in CD71⁺ NRBCs as quantitated by pyrosequencing of bisulfite treated DNA. (B) Methylation at sites −54, −51, and +16 is significantly decreased at maximum tolerated dose (MTD) of hydroxyurea compared with the baseline (BL) methylation before treatment (P < .05). (C) Data are presented as median with interquartile range. Significant inverse correlations between combined methylation of all 5 sites and HbF were detected at baseline and at MTD (D) by the Pearson correlation coefficient.