Systemic lupus erythematosus (SLE), also known simply as lupus, is an autoimmune disease in which the body’s immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary between people and may be mild to severe. Common symptoms include painful and swollen joints, fever, chest pain, hair loss, mouth ulcers, swollen lymph nodes, feeling tired, and a red rash which is most commonly on the face. Often there are periods of illness, called flares, and periods of remission when there are few symptoms.
The cause is not entirely clear. It is believed to involve hormonal, environmental, and genetic factors. Among identical twins, if one is affected there is a 24% chance the other one will be as well. Female sex hormones, sunlight, smoking, vitamin D deficiency, and certain infections, are also believed to increase the risk. The mechanism involves an immune response by autoantibodies against a person’s own tissues. These are most commonly anti-nuclear antibodies and they result in inflammation. Diagnosis can be difficult and is based on a combination of symptoms and laboratory tests. There are a number of other kinds of lupus erythematosus including discoid lupus erythematosus, neonatal lupus, and subacute cutaneous lupus erythematosus.