Limiting the FXS-associated DNA methylation analysis in this group to only those loci that satisfied an FDR <0.05 in the peripheral blood analysis (N = 1183 probes; Figure 1A; see Methods) yielded results similar to those found in peripheral blood: eight FXS-methylated loci and one FXS-demethylated locus; all nine differentially methylated loci are annotated to the FMR1 promoter (Bonferroni <0.05) (Figure 1C; Additional file 8: Table S4). Here, FMR1 is linked to fragile X syndrome.