<unk>  commonly abbreviated as<unk> , is an autoimmune disease characterized by the presence of elevated blood levels of a specific autoantibody, now called anti-U1 ribonucleoprotein (RNP) together with a mix of symptoms of systemic lupus erythematosus (SLE), scleroderma, and polymyositis. The idea behind the<unk> " disease is that this specific autoantibody is also present in other autoimmune diseases such as systemic lupus erythematosus, polymyositis, scleroderma, etc.<unk>  was characterized as an individual disease in 1972 by Sharp et al., and the term was introduced by Leroy in 1980. It is sometimes said to be the same as undifferentiated connective tissue disease, but other experts specifically reject this idea because undifferentiated connective tissue disease is not necessarily associated with serum antibodies directed against the U1-RNP, and<unk>  is associated with a more clearly defined set of signs/symptoms.
Mixed connective tissue disease
Carnitine palmitoyltransferase II
Undifferentiated connective tissue disease
Scleroderma
Systemic scleroderma
Antisynthetase syndrome
CREST syndrome
Cryopyrin-associated periodic syndrome