Autoantibodies to within BGCN homolog (WIBG), GABA(A) receptor-associated protein-like 2 (GABARAPL2), zinc finger protein 706 (ZNF706) and peptidyl arginine deiminase 4 (PAD4) proteins are significantly detected in patients with early rheumatoid arthritis (RA). Sera from RA patients and controls were tested on the 25 purified proteins by ELISA. (A) Optical density (OD) read at 405 nm. The cutoff, marked as a horizontal line, defines positive sera with an OD value higher than twice the mean OD of the control groups (patients with ankylosing spondylitis (AS), psoriatic arthritis (PsA), systemic lupus erythematosus (SLE), systemic sclerosis (SSC) and healthy subjects). (B) Percentage of positive sera. P-values were obtained by comparing the group with early RA to the control groups (AS, PsA, SLE, SSC and healthy subjects).