Autoimmune diseases are a broad category of related diseases in which the person's immune system attacks his/her own tissue. The ability to develop an autoimmune disease is determined by a dominant genetic trait that is very common and may present in families as different autoimmune diseases within the same family. It is important for families with members who have autoimmune diseases to mention this fact when another member of the family is experiencing medical problems that appear to be difficult to diagnose (such as CD). There are just a few of many of the more familiar autoimmune disorders:

Lupus
Multiple Sclerosis
Pernicious anemia
Graves' disease
Myasthenia gravis
Sjogren's syndrome
Insulin dependent diabetes
Scleroderma
Rheumatoid arthritis
Addison's disease
Primary biliary cirrhosis