Epigenetic alterations, such as DNA methylation and histone acetylation, play crucial roles in the onset and pathogenesis of RA by influencing the post-transcriptional expression of key genes involved in synovial inflammation and bone destruction.31,32 Recent studies have highlighted the effect of epigenetic factors, including DNA methyltransferase (DNMT), Lysine-Specific Demethylase 1 (LSD1), and Histone Deacetylase (HDAC), in regulating osteoclastogenesis in RA.33–35 Nevertheless, therapeutic strategies targeting these epigenetic modifications have yet to be validated in RA patients. This evidence concerns the gene HDAC9 and rheumatoid arthritis.