On the other hand, levels of three active chromatin marks, H3 acetylation (H3Ac), H4 acetylation (H4Ac) and H3K4 dimethylation (H3K4me2), were reportedly lowered at the FMR1 promoter in FXS (Gheldof et al. 2006). The gene discussed is FMR1; the disease is fragile X syndrome.