Serum CALC2 levels were assessed in 18 patients with rheumatoid arthritis (RA), 19 patients with ankylosing spondylitis (AS), and 18 age- and sex-matched controls in cohort 1 and 8 patients with OA and 14 age- and sex-matched controls in cohort 2. Here, CALCB is linked to ankylosing spondylitis.