2. Subjects must either have the classic rash(es) of DM (heliotrope, Gottron sign or Gottron papules), possess one of the myositis-associated autoantibodies (e.g. anti-synthetase, anti-SRP, anti-Mi-2, anti-PM-Scl, anti TIF1-γ etc.), or have the diagnosis of PM agreed upon by a 3-member Adjudication Committee consisting of a rheumatologist, neurologist and neuromuscular pathologist.