TRIM21 and overlapping connective tissue disease: Other autoantibodies, including anti-U1-RNP, anti-PM-Scl, anti-Ku, anti-Ro60/SS-A, anti-Ro52/TRIM21, and anti-NOR 90 tend to be found in SSc-overlap syndromes as well as in other ARD, and are considered less specific for SSc (Table 1) (2).