Mixed Connective Tissue Disease
Mixed connective tissue disease (MCTD) is a rare autoimmune disorder that causes signs and symptoms of several other connective tissue diseases. People with mixed connective tissue disease can experience features of more than one autoimmune musculoskeletal disease - commonly lupus, scleroderma and polymyositis. For this reason, mixed connective tissue disease is sometimes referred to as an overlap disease.
Signs and symptoms of these diseases usually don't appear all at once. This makes diagnosing mixed connective tissue disease somewhat complicated. Often people with mixed connective tissue disease are first diagnosed with lupus. As the disease progresses and other signs and symptoms become apparent, the diagnosis is corrected. There can be characteristic antibodies seen on blood tests associated with mixed connective tissue disease, although this isn't always the case.
Mixed connective tissue disease occurs most often in women and is usually diagnosed in young adults in their 20s and 30s. However, children have occasionally been diagnosed with mixed connective tissue disease.
Information courtesy of the Mayo Clinic.