Lupus is a complex disease, and its cause is unknown. It is likely that a combination of genetic, environmental, and possibly hormonal factors work together to cause the disease. Scientists are making progress in understanding lupus, as described here and in the "Current Research" section of this booklet. The fact that lupus can run in families indicates that its development has a genetic basis. Recent research suggests that genetics plays an important role; however, no specific "lupus gene" has been identified yet. Studies suggest that several different genes may be involved in determining a person's likelihood of developing the disease, which tissues and organs are affected, and the severity of disease. However, scientists believe that genes alone do not determine who gets lupus and that other factors also play a role. Some of the factors scientists are studying include sunlight, stress, certain drugs, and infectious agents such as viruses.
It is likely that a combination of...factors work together to cause the disease.
In lupus, the body's immune system does not work as it should. A healthy immune system produces proteins called antibodies and specific cells called lymphocytes that help fight and destroy viruses, bacteria, and other foreign substances that invade the body. In lupus, the immune system produces antibodies against the body's healthy cells and tissues. These antibodies, called autoantibodies, contribute to the inflammation of various parts of the body and can cause damage to organs and tissues. The most common type of autoantibody that develops in people with lupus is called an antinuclear antibody (ANA) because it reacts with parts of the cell's nucleus (command center). Doctors and scientists do not yet understand all of the factors that cause inflammation and tissue damage in lupus, and researchers are actively exploring them.
Symptoms of Lupus
Each person with lupus has slightly different symptoms that can range from mild to severe and may come and go over time. However, some of the most common symptoms of lupus include painful or swollen joints (arthritis), unexplained fever, and extreme fatigue. A characteristic red skin rash-the so-called butterfly or malar rash-may appear across the nose and cheeks. Rashes may also occur on the face and ears, upper arms, shoulders, chest, and hands. Because many people with lupus are sensitive to sunlight (called photosensitivity), skin rashes often first develop or worsen after sun exposure.