A 28-year-old woman has Raynaud phenomenon, proximal muscle weakness with elevated creatine kinase, arthralgia, puffy fingers, and a positive antinuclear antibody with speckled pattern. She lacks antibodies to Sm, centromere, or topoisomerase I. The single autoantibody that best supports a unifying diagnosis in this case is:

• A Anti SSA/Ro
• B Anti double stranded DNA
• C Anti Jo 1 (histidyl tRNA synthetase)
• D Anti U1 ribonucleoprotein (anti nRNP) ✓

Explanation

Mixed connective tissue disease is defined clinically by overlapping features of SLE, systemic sclerosis, and polymyositis, together with high titers of antibodies against U1 ribonucleoprotein (U1 snRNP), which produces a speckled ANA pattern. Anti dsDNA is specific for SLE and argues against MCTD, anti Jo 1 marks the antisynthetase syndrome with interstitial lung disease and mechanic hands, and anti SSA/Ro is associated with Sjogren syndrome and neonatal lupus rather than this overlap picture.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.