FMR1 and fragile X syndrome: These findings confirm the dynamic role of R-loops in the pathogenesis of FXS (Lee et al., 2023); Regarding 3D genome regulation, the latest research has found that in various cell types of FXS patients, the expansion of the CGG sequence triggers the formation of large-scale H3K9me3 regions around the autosomes and the FMR1 gene, leading to significant adjustments in chromatin structure, accompanied by severe structural disorder of topologically associating domains (TADs) and chromatin loops.