FMR1 and fragile X syndrome: (hydroxy-)methylated DNA immunoprecipitation assays, (h)MeDIP, were used to investigate the DNA methylation (5mC) and hydroxymethylation (5hmC) landscape of the broader FMR1 locus in peripheral blood mononuclear cells (PBMC) samples from eight fragile X syndrome patient and four control individual samples (Fig. 1a).