What causes granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA)?

Answers from April Chang-Miller, M.D.

The exact causes of GPA — formerly known as Wegener's granulomatosis — and MPA are unknown.

GPA and MPA are both types of inflammation of the blood vessels (vasculitis). It is believed that one or more genetic and environmental factors, such as infections, allergic reactions, certain drugs and diseases, might trigger an abnormal immune system response that causes GPA and MPA symptoms. However, no specific infection or event has been identified as the cause.

GPA and MPA develop when the immune system mistakenly identifies blood vessel cells as foreign invaders and attacks them. The vessels become inflamed, causing them to narrow or close off, disrupting the flow of blood to various organs and causing organ and tissue damage. No matter the cause, early diagnosis and treatment of GPA and MPA are essential for a full recovery.

July 17, 2014 See more Expert Answers