Predictor of Clinical Response to Acthar in Myositis

Inclusion Criteria: * Healthy Controls: * An individual will be eligible to be a control subject if his/her age is 18 years or greater. * Myositis Remission Control Group * Definite or probable PM or DM by Bohan and Peter criteria. * PM patients must either possess a myositis-associated autoantibody or undergo adjudication for confirmation of the PM diagnosis by consensus of two experts (Aggarwal or Oddis) to ensure non-PM patients are not enrolled. This step is necessary since there are well known mimics of PM. * Age is greater than or equal to 18 years * Remission of myositis as defined by a myositis disease global activity score \<1 on the MDAAT and no new immunosuppressive or glucocorticoid therapy or dose change within one year. Exclusion Criteria: * Healthy Controls: * An existing diagnosis of a CTD * A potential immune compromised state, for example, treatment with immunosuppressant or anti-rejection medication or a diagnosis of an immune deficiency disease * Myositis Remission Control Group: * Juvenile DM or PM, myositis in overlap with another connective tissue disease, cancer associated myositis, inclusion body myositis, or any other non immune mediated myopathy. * Severe muscle damage defined as a baseline global muscle damage score on the MDI (Myositis Damage Index) of greater than or equal to five centimeters on a ten centimeter VAS. * Patients with malignancy within three years of screening (except basal cell cancer or squamous cell ca…