This test detects antibodies directed against the 70-kilodalton (70kD) protein of the U1-ribonucleoprotein complex. These antibodies are strongly associated with mixed connective tissue disease (MCTD) and can also appear in systemic lupus erythematosus (SLE).

  • Diagnostic Value: Anti-RNP-70 is particularly important in identifying MCTD, a condition with overlapping features of lupus, scleroderma, and polymyositis.
  • Disease Differentiation: The presence of Anti-RNP-70 helps distinguish MCTD from lupus and other autoimmune conditions when symptoms overlap.
  • Clinical Insight: Patients with these antibodies may present with joint pain, Raynaud’s phenomenon, muscle weakness, or skin changes — making early detection essential for monitoring disease progression.

Because of its specificity, the Anti-RNP-70 test is a key tool in diagnosing and differentiating autoimmune connective tissue diseases.