A variety of autoantigens that elicit T-cell responses in patients with SSc are widely distributed in tissues, have been described, and include types I, II, and V CIs (CI, CII, CV); laminin; low molecular weight (MW) N-sulfated heparin sulfate; 3500 MW RNA antigen; elastin; and DNA topoisomerase I (189, 194–198). This evidence concerns the gene TOP1 and systemic sclerosis.