Methylation of γ- and β-globin promoter sequences in fetal hepatocytes and adult CD34⁺ peripheral blood hematopoietic cells. (A) Methylation of the 2 γ-globin promoters and the β-globin promoter in purified fetal hepatocytes. Data from 2 independent samples are shown. (B) Methylation of the γ- and β-globin promoters in CD34⁺ peripheral blood cells. □ indicates unmethylated; ■, methylated; and ▩, indeterminate sequencing.