FMR1 and fragile X syndrome: In an effort to understand why there is FMR1 mRNA buildup in FXTAS pathology, Todd et al. (2010) examined histone acetylation at the human FMR1 locus and found, interestingly, that histone acetylation was increased at the FMR1 locus in premutation carriers compared to control or FXS-derived cell lines, which correlated with increased FMR1 mRNA levels in premutation cell lines.