Which antibody is diagnostic of mixed connective tissue disease: (A) Anti-histidyl t-RNA synthetase, (B) Anti-U1-ribonucleoprotein, (C) Anti-Myeloperoxidase, (D) Anti-Proteinase-3
Answer is B. Anti-U1-ribonucleoprotein - MCTD
Anti-histidyl t-RNA synthetase - Inflammatory myopathies.