Mixed connective tissue disease (MCTD) is a syndrome with features of scleroderma, rheumatoid arthritis, SLE and polymyositis-dermatomyositis.
The manifestations of the disease include arthritis, Raynaud's phenomenon, scleroderma of the fingers, muscle weakness and tenderness, interstitial lung disease and a skin rash resembling dermatomyositis or SLE.
These patients have antibodies to U1 snRNP in high titre. Renal disease is unusual in these patients. The disease appears to respond to moderate doses of corticosteroids.