Mixed Connective Tissue Disease (MCTD) By Alana M Nevares, MD, The University of Vermont Medical Center Reviewed / Revised Oct 2022 View Patient Education Symptoms and Signs Diagnosis Prognosis Treatment Key Points Topic Resources Raynaud Syndrome With Pallor Raynaud Syndrome With Cyanosis Mixed connective tissue disease is an uncommon, specifically defined syndrome characterized by clinical features of systemic lupus erythematosus, systemic sclerosis, and polymyositis with very high titers of circulating antinuclear antibody to a ribonucleoprotein antigen.