Elevated CXCL13 serum levels have been associated with synovitis in RA [17], and serum CXCL13 is decreased following treatment of RA patients with TNF-α inhibitors and anti-CD20 rituximab [17-19], thus implicating CXCL13 as a robust biomarker of RA disease activity. The gene discussed is CXCL13; the disease is rheumatoid arthritis.