Besides the ACPA (and RF)-associated RA phenotype associated with poor long-term prognosis, we have, for example, defined an acute-onset RA phenotype associated with high levels of antibodies against native human CII [34,35], whereas others have described a mild RA phenotype associated with antibodies against the RA33 antigen [36]. The gene discussed is PRTN3; the disease is rheumatoid arthritis.