It has previously been shown that the presence of antibodies against citrullinated proteins/peptides (ACPA), analysed as anti-cyclic citrullinated peptide (CCP) antibodies of immunoglobulin (Ig)G, IgA, and IgM isotypes, precedes the development of RA by several years [1-4]. The gene discussed is PRTN3; the disease is rheumatoid arthritis.