Types of Lupus Disease

Although "lupus" is used as a broad term, there actually are several kinds of lupus:

Systemic lupus erythematosus

(SLE) is the form of the disease that most people are referring to when they say "lupus." The word "systemic" means the disease can affect many parts of the body. The symptoms of SLE may be mild or serious. Although SLE usually first affects people between the ages of 15 and 45 years, it can occur in childhood or later in life as well. This booklet focuses on SLE.

Discoid lupus erythematosus

Refers to a skin disorder in which a red, raised rash appears on the face, scalp, or elsewhere. The raised areas may become thick and scaly and may cause scarring. The rash may last for days or years and may recur. A small percentage of people with discoid lupus have or develop SLE.

Drug-induced lupus

Refers to a form of lupus caused by specific medications. Symptoms are similar to those of SLE (arthritis, rash, fever, and chest pain) that typically go away when the drug is stopped.

Neonatal lupus

A rare form of lupus affecting newborn babies of women with SLE or certain other immune system disorders. At birth, the babies have a skin rash, liver abnormalities, or low blood counts, which entirely go away over several months. However, babies with neonatal lupus may have a serious heart defect. Physicians can now identify most at-risk mothers, allowing for prompt treatment of the infant at or before birth. Neonatal lupus is very rare, and most infants of mothers with SLE are entirely healthy.

Understanding What Causes Lupus

Lupus is a complex disease whose cause is unknown. It is likely that there is no single cause but rather a combination of genetic, environmental, and possibly hormonal factors that work together to cause the disease. The exact cause may differ from one person to another. Scientists are making progress in understanding the processes leading to lupus, as described here and in the Current Research section. Research suggests that genetics plays an important role; however, no specific "lupus gene" has been identified. Instead, it appears that several genes may increase a person's susceptibility to the disease.

The fact that lupus can run in families indicates that its development has a genetic basis. In addition, studies of identical twins have shown that lupus is much more likely to affect both members of a pair of identical twins, who share the exact same set of genes, than two nonidentical twins or other siblings. However, scientists think that genes alone cannot account for who gets lupus. Other factors must also play a role. Some of the factors that scientists are studying include sunlight, stress, certain drugs, and infectious agents such as viruses. Even though a virus might trigger the disease in susceptible individuals, a person cannot "catch" lupus from someone else.

In lupus, the body's immune system does not work as it should. A healthy immune system produces substances called antibodies 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 ("auto" means self), contribute to the inflammation of various parts of the body, causing damage and altering the function of target organs and tissues. In addition, some autoantibodies join with substances from the body's own cells or tissues to form molecules called immune complexes. A buildup of these immune complexes in the body also contributes to inflammation and tissue injury in people with lupus. Researchers do not yet understand all of the factors that cause inflammation and tissue damage in lupus, and this is an active area of research.