Berens HM, Polinski KJ, Mikuls TR, et al. - In 678 first-degree relatives (FDR) of people with RA and 330 with OA, serum was examined for anti-cyclic citrullinated peptide (anti-CCP)3.1 (IgG/IgA) in order to examine the relationship of age and anti-CCP in people without RA. In FDR, growing age was significantly related to positivity for anti-CCP3.1 and anti–CCP-IgA yet not anti–CCP-IgG. In FDR and OA people, the anti-CCP3.1 prevalence was significantly raised following the age of 50 years. Thus, in individuals without RA, the growing age should be taken into account in the interpretation of anti-CCP3.1 positivity.