The rare disease that killed comedy legend Harold Ramis narrows the blood vessels, slowly starving the organs they supply.

Ramis died today at the age of 69 from complications of vasculitis, an autoimmune disease in which the body attacks its own arteries and veins. The severity depends on the degree of the inflammation in the blood vessels and the organs affected. And while some cases of go into remission with treatment, others are chronic, debilitating and deadly.

Ramis had been battling vasculitis for four years, according to a statement from his agency.

Find out more about Ramis's work.

Symptoms of vasculitis include fever, loss of appetite, weight loss, fatigue and general aches and pains, according to the National Institutes of Health. Depending on the organs affected, it can also cause splotchy skin, shortness of breath, blindness, hearing loss, muscle weakness and paralysis.

Blood tests can detect disease-causing antibodies and other markers of inflammation to help diagnose the condition, and a biopsy can confirm the narrowing of the blood vessels. An X-ray taken while special dye flows through the blood vessels, known as angiography, can also help diagnose the disease.

Find out about clinical trials for vasculitis.

Ramis is survived his wife, Erica, sons Julian and Daniel, daughter Violet and two grandchildren.

Harold Ramis battled vasculitis for four years, (Image credit: Ron Galella, Ltd./WireImage/Getty Images)