Discovery and validation of blood methylation variation associated with the response tumor necrosis factor inhibitors in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the joints that has been associated with changes in the blood methylome. There is high interest to determine if this accessible epigenetic variation is associated with relevant clinical outcomes. An initial longitudinal cohort of n=62 RA patients starting anti-TNF therapy was analyzed by means of the EPIC methylation array (850,000 probes). Methylation profiles were analyzed at baseline and at week 12 of treatment. Association of whole blood epigenetic variation with the clinical response to therapy and with disease activity were performed both at the CpG and biological pathway levels