Mixed connective tissue disease

Now understood to be a distinct disease, mixed connective tissue disease (MCTD) is variously considered an overlap between systemic lupus erythematosus, scleroderma, and polymyositis; a specific subest of  scleroderma with objective features of other diseases, such as SLE or polymyositis; or a distinct disease entity.

Most patients with MCTD have autoantibodies to U1 small nuclear ribonucleoproteins (anti-U1 snRNP OR anti-U1 RNP),