Mikuls TR, Edison J, Meeshaw E, et al. - Researchers assessed serum autoantibodies to malondialdehyde–acetaldehyde (MAA) before the diagnosis of  rheumatoid arthritis (RA). This study involved cases (n = 214) and controls (n = 210). The samples from both groups were taken to assess levels of anti‐MAA antibody isotypes, anti–cyclic citrullinated peptide 2 (anti–CCP‐2), and IgM rheumatoid factor prior to as well as post-RA diagnosis. Findings revealed raised IgG and IgA anti‐MAA autoantibodies before RA diagnosis but these appeared in the preclinical course compared with anti–CCP‐2 or rheumatoid factor. A likely role of MAA formation as well as of anti‐MAA immune responses in the transition from subclinical autoimmunity to clinically apparent arthritis was also suggested.