Anti-Carbamylated Protein Antibodies in Psoriatic Arthritis

Anti-carbamylated protein (anti-CarP) antibodies are present in approximately one-fourth of the patients who are seronegative for both rheumatoid factor and anti-citrullinated protein antibody and who may therefore have psoriatic arthritis. The investigators hypothesized that detection of anti-CarP antibodies in serum may be useful for diagnosis of psoriatic arthritis.