However, similar to what is observed in FXS embryos, when the cells are cultured under differentiation conditions, there is a downregulation of the transcript, acquisition of CpG DNA methylation, loss of H3K9 acetylation, and gain in H3K9 methylation at the Fmr1 locus (Fig. 3) [114]. Here, FMR1 is linked to fragile X syndrome.