•Serum anti-MAA (IgG) Ab positivity more frequent in RA vs. non-RA•No association of anti-MAA status with HLA-DRB1 shared epitope•Anti-MAA positivity more common in ACPA (-) participants with HLA-DRB1*03 and associated with radiological progression. The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.