Fig. 4

Repressive epigenetic switch spanning entire FMR1 locus in FXS PBMCs. Relative ChIP-qPCR enrichment of the indicated chromatin histone post-translational modifications (H3K4me2, H3K9me2, H3K9me3, and H4K20me1) in three control (blue) and eight (red) patients samples (A to H, as in Fig. 2). Data represent the mean of relative enrichment to input in log2 with standard deviation SD (left panels). Significance levels of the mean difference in control and FXS PBMCs is indicated by triple asterisks p ≤ 0.001, double asterisks p ≤ 0.01, single asterisk p ≤ 0.05, or no star p > 0.05 using a t test with unequal variance (Additional file 11: Table S4). The bar graphs on the right hand-side represents individual patient data for the indicated marks in region 2I3-4 located in the first intron of the FMR1 gene. The upper panel illustrates the FMR1 locus organization with pyrosequencing (HsFMR1 and B3) as well as PCR assays locations (listed in Additional file 1: Table S1 and Additional file 9: Table S2)