TRIM21 and polymyositis: The autoantigen arrays, which were incubated with a mixture of sera derived from patients with SLE, polymyositis (PM), or primary biliary cirrhosis (PBC), specifically identified autoantibodies recognizing mammalian double-stranded DNA (dsDNA), synthetic single-stranded DNA (ssDNA), histone H2A, U1 small nuclear ribonucleoprotein (U1-snRNP), Smith antigen (Sm), Sm/RNP complexes, Ro52, Jo-1, and pyruvate dehydrogenase (PDH).