Many of the autoimmune diseases are rare. As a group, however, autoimmune diseases afflict millions of Americans.
Some autoimmune diseases occur more frequently in certain minority populations.
For example, lupus is more common in African-American and Hispanic women than in Caucasian women of European ancestry. Rheumatoid arthritis and scleroderma affect a higher percentage of residents in some Native American communities than in the general U.S. population.