DNA methylation analysis of the KLF1 gene. (A) Regulation of β-like globin expression in erythropoietic cells by transcription factors BCL11A and KLF1. LCR, locus control region. (B) Target regions (gray) in the KLF1 gene locus that were analyzed for methylation by mass spectrometry. (C) CpG methylation of the KLF1 enhancer region (mean of 5 CpG sites) in GPEP cells of adults, newborns, and patients with JMML. (D) KLF1 enhancer methylation in non-GPEP cell populations of adults, newborns, and patients with JMML. (E) KLF1 enhancer methylation in the erythroleukemia cell line K562 and the non-erythroid myeloid leukemia cell line HL60. Mann-Whitney test: NS, not significant; **P ≤ 0.01.