Blinded sera from 631 patients (409 consecutive out-patients and 222 randomly selected stored sera) with RA (n = 164) and non-RA (osteoarthritis [n = 120], polymyalgia rheumatica/giant cell arteritis [n = 80], spondyloarthritis [n = 36], and other inflammatory rheumatic or non-inflammatory disease [n = 67]) were tested for the presence of anti-MCV and anti-CCP2 antibodies according to the manufacturers' instructions. Here, AGBL2 is linked to spondyloarthropathy.