THURSDAY, Sept. 30 (HealthDay News) -- Antibodies against peptidyl arginine deiminase type 4 (PAD-4) are a specific early marker of rheumatoid arthritis (RA), according to research published in the September issue of Arthritis & Rheumatism.
Jason R. Kolfenbach, M.D., of the University of Colorado Denver in Aurora, and colleagues conducted a study of 83 patients with RA and 83 controls using stored serum samples to determine if antibodies against PAD-4 are present in the preclinical phase of RA. The researchers also compared the timing of the onset of these antibodies to those of other preclinical antibodies.
In the RA group, the researchers found that 18.1 percent had at least one sample positive for anti-PAD-4, compared to only 1.2 percent in the control group; this equated to a sensitivity of 18.1 percent and a specificity of 98.8 percent. PAD-4 was present in the serum for a mean of 4.67 years before the clinical diagnosis of RA, and was associated with anti-cyclic citrullinated peptide (anti-CCP) positivity, although anti-CCP positivity occurred earlier than PAD-4 69 percent of the time.
"Further research is needed to investigate the relative timing of the appearance of multiple autoantibodies in preclinical RA, the physiologic implications of autoantibody binding to the PAD-4 enzyme, and the potential influence on disease development and severity," the authors write.
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