Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare immune system disorder that causes asthma, an excessive number of eosinophils (a type of white blood cell) in the blood, and the inflammation of blood vessels, or vasculitis. In order to properly treat EGPA, it is critical that the level of disease activity can be determined over the course of the disease. The purpose of this study is to determine new biological markers, or biomarkers, that may be used to assess the severity of this disease in people with EGPA.

EGPA, also known as allergic granulomatosis angiitis, is a systemic vasculitis. EGPA is marked by three distinct symptoms: asthma; eosinophilia, evidenced by an excessive number of eosinophils in the blood and tissues; and vasculitis involving the skin, lungs, nerves, kidneys, and other organs. Nerve involvement may also occur in EGPA, causing pain, tingling, numbness, and muscle wasting in the hands and feet. Because EGPA patients may not show any visible signs of active disease, current methods of monitoring disease progression usually represent a period of extended inflammation and disease activity. Thus, patients may go untreated during a period of undetectable disease when damage might be preventable. This study will use novel scientific methods to identify new biomarkers that can be used to monitor disease activity in EGPA patients. These biomarkers may be used to help direct clinical care for EGPA patients and assist in future drug development.

Study visits will occur every 6 months, or annually. Blood and urine collection will occur at every visit. A physical exam and medical and medication history will at every visit; also, participants will be asked to complete several questionnaires to assess disease activity, health status, and tobacco, alcohol, and drug use.

Inclusion Criteria:

Patients with a diagnosis of eosinophilic granulomatosis with polyangiitis are eligible for the study.

Parent or guardian willing to provide informed consent, if applicable

Exclusion Criteria:

- Inability to give informed consent and to sign the consent form

Individuals with eosinophilic granulomatosis with polyangiitis (Churg-Strauss). Enrollment will be sequential and participants will have disease in various stages and of different duration.