As the name implies, MCT disease contains elements of several rheumatoid-collagen entities, including SLE, PSS, and dermatomyositis. Clinically, there is arthralgia or arthritis in 90%-95% of patients, Raynaud’s phenomenon in about 80%-90%, abnormal esophageal motility in about 70%, muscle pain in about 70%, and fever in about 30%. There is a low incidence of renal disease. Various autoantibodies have been found, and there is a positive ANA test result in more than 95% (usually with a speckled pattern), elevated SS-A in up to 50% of cases, and elevated anti-dsDNA antibody in about 25%. The characteristic serologic feature of MCT disease is a high titer of autoantibody against RNP in 95%-100% of patients. Lesser degrees of RNP elevation are found in some patients with SLE and PSS.