Eligibility Criteria

• Participation requires siblings of the same gender — one sibling diagnosed in the last five years with adult or juvenile rheumatoid arthritis, lupus, scleroderma, or myositis, and one brother or sister who does NOT have an autoimmune disease.
• Twins are encouraged to participate, but siblings within five years age difference may also join.

The minimum inclusion criteria needed for enrollment are a twin pair or sibling pair, as defined by an eligible proband and his/her eligible twin or sibling, willing and able to give informed consent, to enroll in the study, to complete the questionnaires and to donate blood and urine samples (in case of children, parent/legal guardian must also be willing and able to provide informed consent).

Proband inclusion criteria:

• Children (< 18 years of age) or adults (18 or more years of age) require a diagnosis of a systemic rheumatic disorder (by American College of Rheumatology (ACR) or other criteria for the adult or juvenile forms of RA, SLE, SSc, or IIM (per (92;93)). Regarding the childhood-onset diseases: JRA will be defined by age of onset <17 years of age; for other diseases age of onset will be <18 years. Probands will be diagnosed within 5 years of enrollment in the study, with at least one twin or other sibling of the same gender within 5 years of age and without a recognized systemic rheumatic disorder or other autoimmune disease available for study.

Twin-sibling inclusion criteria:

• Children or adults who are twins or other siblings of a proband sharing the same biological parents, but without a recognized systemic rheumatic or autoimmune disorder, of the same gender and within 5 years of age of the proband. If monozygotic twins are enrolled from a family, another unaffected non-twin sibling sharing the same biological parents will be enrolled for each proband if available to allow for log-linear genetic analyses. All probands and unaffected siblings need to be at least one year of age at the time of autoimmune disease diagnosis. In the case of triplets or greater multiples, all such siblings are eligible for enrollment.

Parent inclusion criteria:

• Individuals who are the genetic father and mother of the proband and twin-sib. Both parents will be enrolled whenever possible.

Healthy volunteer inclusion criteria:

• Healthy controls, recruited in part via the NIH Healthy Volunteers program, and as reasonably as possible, matched to a subset of probands based on age (within 5 years), gender, and race (when feasible). Healthy volunteers should be in good health, without a recognized systemic rheumatic disorder or other autoimmune disease, and should not be taking antiinflammatory medicines, including nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroids.

For all subjects: ability of the subject or parents/legal guardians to provide informed consent to all aspects of the study after full protocol information is provided.

Should a participant enroll at a time when his/her twin/sibling is willing and able to give informed consent, but his/her twin/sibling never enrolls (eg. Due to no longer being willing or able to give informed consent), the enrolled participant will remain in the study and his/her data will be used in the analyses not pertinent to his/her twin/sibling. Data analysis will also occur in this manner should the enrolled participant s sibling enroll, but never send in blood samples and/or questionnaires.