In all the studies, a number of differentially methylated sites are located in genes known to be associated with osteoarthritis such as RUNX1, RUNX2, NFATC1, ADAMTS-4, COL9A3, COL11A2, and FGFR2 (Fernández-Tajes et al., 2014; Jeffries et al., 2014; Rushton et al., 2014; Alvarez-Garcia et al., 2016; Zhang et al., 2016a; Bonin et al., 2016). Here, RUNX2 is linked to osteoarthritis.