In conclusion, by focusing on specific T cell populations highly relevant for RA (CD4+ naïve and memory T cells) from two phenotypically distinct and homogeneous RA cohorts using an epigenome wide RRBS sequencing approach, we discovered intrinsic DNA methylation differences, including confirmation of decreased DNA methylation in CpGs within GALNT9 in RA patients. Here, GALNT9 is linked to rheumatoid arthritis.