Mixed connective tissue disease, as first described in 1972, is “classically” considered as an “overlap” of three diseases, systemic lupus erythematosus, scleroderma, and polymyositis. Patients with this pattern illness have features of each of these three diseases. They also typically have very high quantities of antinuclear antibodies (ANAs) and antibodies to ribonucleoprotein (anti-RNP) detectable in their blood. The symptoms of many of these patients eventually evolve to become dominated by features of one of three component illnesses, most commonly scleroderma.
It is now known that overlap syndromes can occur that involve any combination of the connective tissue diseases. Therefore, for example, patients can have a combination of rheumatoid arthritis and systemic lupus erythematosus (hence, the coined name “rhupus”).
How is mixed connective tissue disease diagnosed?
Today, true mixed connective tissue disease is diagnosed when patients demonstrate the clinical features (exam findings) of overlap illnesses (as described above) and have high amounts of the antibodies ANA and anti-RNP in their blood. Mixed connective tissue disease patients do not typically have antibodies such as dsDNA, Scl70, which are particularly common in systemic lupus erythematosus and scleroderma respectively. » Continue reading What is mixed connective tissue disease (MCTD)? »

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