No one knows the exact cause or causes of autoimmune diseases. However, research scientists believe that genetics and the environment both play a role in a person developing the condition.
(Click Autoimmune Disease Cause for more information.)
There are more than 80 types of autoimmune diseases that can affect almost any organ or system of the body. One way to group these diseases is by the body system(s) they attack. The body systems that autoimmune diseases can affect include:
- Blood and blood vessels
- Digestive tract (including the mouth)
- Nerves and brain
(Click Types of Autoimmune Diseases for the complete list and to learn more.)
Autoimmune diseases can affect almost any organ or body system. The exact symptoms will depend on which tissues are targeted. In many people, the first symptoms are fatigue, muscle aches, and low fever.
(Click Autoimmune Disorder Symptoms for more information.)
Autoimmune diseases often don't show a clear pattern of symptoms at first, which can make an autoimmune disease diagnosis difficult. However, with time, doctors can make a diagnosis by performing a physical exam, asking a number of questions about a person's medical history, and ordering certain tests or procedures. However, a diagnosis can take time, and it may take several visits to find out exactly what is wrong and to find the best treatment.