CTCF and Friedreich ataxia: Similar chromatin remodeling occurs at the FXN locus in FRDA patient tissues where expanded FXN alleles display increased DNA methylation, H3K9me2/3, H3K27me3, HP1 recruitment, and a loss of CCCTC-binding factor (CTCF) binding at sites flanking the expanded GAA repeats (17–21).