Disease-specific autoantibodies directed against post-translation citrullinated proteins/peptides (ACPAs) are specific serological markers for rheumatoid arthritis (RA) and have been accepted as one of the classification criteria for the disease. Beyond diagnosis these autoantibodies have also been shown also to predict disease severity. These autoantibodies can be detected several years prior to the clinical onset of RA, with increasing titers overtime, as disease onset is established.