Anti-RNA polymerase III antibodies in systemic sclerosis: Multicentric study from Argentina.

OBJECTIVE: To describe the frequency of anti-RNA polymerase III antibody in patients with Systemic Sclerosis (SSc) of a group of healthcare centres from Argentina and to explore differences among patients with positive and negative anti-RNA polymerase III antibody. PATIENTS AND METHODS: Data from clinical records, anamnesis and physical examination were collected from 135 patients with SSc (ACR/EULAR 2013). A serum sample from each patient was obtained for the detection of anti-RNA polymerase III IgG antibodies by ELISA. RESULTS: In all, 97.8% were women and the median age at diagnosis was 53 years (range 12-87), 77.7% had limited cutaneous SSc (lcSSC), 19,3% patients had diffuse cutaneous SSc (dcSSC) and 2.9% had scleroderma sine scleroderma. The 67.5% of the patients were from a Mestizos or Amerindian ethnic group. Anti-RNA polymerase III was positive in 5.9% of the patients. In 36 patients, the anticentromere (ACA) and anti-Scl70 antibodies were negative; anti-RNA polymerase III was positive in 16.7% of these 36 patients. Pitting scars and pulmonary artery hypertension were more frequent in anti-RNA polymerase III positive patients who were also older at diagnosis. No association with gastric antral vascular ectasia was found. The only patient with scleroderma renal crisis was anti-RNA polymerase III positive. CONCLUSIONS: Anti-RNA polymerase III frequency found in this study was one of the lowest reported, which could be related to the predominance of the Amerindian and Mestizo ethnic group. It is possible that the detection of anti RNA polymerase III allows better classification of SSc patients, to know their prognosis and to improve their follow-up, therefore more studies are needed.