Definition
By Mayo Clinic staffMixed connective tissue disease (MCTD) is an uncommon autoimmune disorder that causes overlapping features of primarily three connective tissue diseases — lupus, scleroderma and polymyositis. Mixed connective tissue disease also may have features of rheumatoid arthritis. For this reason, mixed connective tissue disease is sometimes referred to as an overlap disease.
Indications of these diseases usually don't appear all at once, which complicates the diagnosis of mixed connective tissue disease. People with mixed connective tissue disease often are first diagnosed with lupus. As the disease progresses and other signs and symptoms become apparent, the diagnosis is updated.
Mixed connective tissue disease occurs most often in women and is usually diagnosed in their 20s and 30s. Occasionally children are diagnosed with mixed connective tissue disease.
- Bennett RM. Clinical manifestations of mixed connective tissue disease. http://www.uptodate.com/home/index.html. Accessed Dec. 15, 2009.
- Mixed connective tissue disease (MCTD). The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec04/ch032/ch032c.html. Accessed Dec. 25, 2009.
- Hoffman RW, et al. Immune pathogenesis of mixed connective tissue disease: A short analytical review. Clinical Immunology. 2008;128:8.
- Bennett RM. Definition and diagnosis of mixed connective tissue disease. http://www.uptodate.com/home/index.html. Accessed Dec. 15, 2009.

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