AntiRNAP

AntiRNAP refers to autoantibodies directed against RNA polymerase enzymes, most notably RNA polymerase III. The antibodies typically target the POLR3A and POLR3B subunits, though antibodies against other RNA polymerase components have been described less commonly. Anti-RNA polymerase I or II antibodies are rarer and less well characterized.

In clinical practice, anti-RNA polymerase III antibodies are most strongly associated with systemic sclerosis (scleroderma), particularly the diffuse cutaneous form. Their presence is linked to more rapid skin involvement and an increased risk of scleroderma renal crisis. Several studies have also reported an association between anti-RNA polymerase III antibodies and cancer diagnosed near the onset of systemic sclerosis, suggesting a potential cancer-associated autoimmune subset. The mechanisms behind these associations remain an area of ongoing research; one hypothesis involves an immune response to tumor-associated RNA polymerase III antigens that cross-reacts with normal tissues.

Detection of anti-RNA polymerase III antibodies is performed in specialized laboratories using assays such as immunoprecipitation and enzyme-linked immunosorbent assays (ELISA). Results are interpreted as biomarkers that aid in disease subset classification and prognosis rather than as direct drivers of disease.

Related information includes other systemic sclerosis–associated autoantibodies, such as anti-centromere and anti-topoisomerase I, which help define disease subsets and guide clinical management.