Eligibility Criteria

• This study is no longer recruiting participants
• Ages Eligible for Study: 18-90 years
• Genders Eligible for Study: All
• Military personnel and veterans who have symptoms of myositis (polymyositis, dermatomyositis, or inclusion body myositis) during military service.
• Military personnel and veterans who do not have an autoimmune or muscle disease that can be matched with a myositis patient.

For Aim 1 study:

Inclusion Criteria for Myositis Subjects:

• Diagnosis of PM, DM or IBM during military service. Subjects may be active duty or no longer active duty personnel. A matrix diagnosis of myositis will be based on ICD-9 and ICD-10 codes, laboratory tests and medical records in an attempt to match criteria for probable or definite PM, DM or IBM.

Inclusion Criteria for Matched Control Subjects:

• The same gender, race, age within 10 years, and service in the military within 10 years as the myositis subject.

For Aims 2 and 3 of the study:

Inclusion Criteria for Myositis Subjects:

• Diagnosis of myositis during military service or service as a military contractor based on criteria for probable or definite PM or DM, or clinically or pathologically defined or possible IBM. Subjects may be active duty or no longer active duty personnel. Military contractors include those with at least 1 year of collective service on a military base or who actively deployed with military units after October 1998 and developed myositis will be eligible for this study.
• Able and willing to give informed consent, to complete the questionnaires and to donate blood samples.

Inclusion Criteria for Matched Control Subjects:

• Persons with military experience or having served as a military contractor attending the same clinic or hospital as the myositis subject to which they are matched, or if not available, volunteers from the general community (such as other participating military or VA hospitals, private HCPs, or the NIH Healthy volunteer program), gender- race- and age- (within 10 years) and military service period (within 10 years) matched to the myositis subject. Military contractors include those with at least 1 year of collective service on a military base or who actively deployed with military units after October 1998.
• Controls should be without a recognized autoimmune or chronic muscle disease, able and willing to give informed consent, to complete the questionnaires and to donate blood samples.