Lupus erythematosus, known as systemic lupus erythematosus (SLE), is an autoimmune disease in which pathogenic autoantibodies and immune complexes form and mediate damage to organs and tissues, and there are often clinical manifestations of multisystem involvement, with a variety of autoantibodies represented by antinuclear antibodies in the serum. The main causes are as follows: 1. Genetic: ① Epidemiological and family surveys: some data show that 8 times more SLE patients have SLE in the first generation of relatives than in families without SLE patients, and 5-10 times more monozygotic twins have SLE than dizygotic twins. (2) Susceptibility genes: Studies have demonstrated that SLE is a polygenic disease, and it is assumed that multiple genes interact under certain conditions to alter the normal immune tolerance and cause the disease. However, the SLE-related genes found now can only explain about 15% of the genetic possibility. 2, environmental factors: ① sunlight: ultraviolet light causes apoptosis of skin epithelial cells, and new antigens are exposed and become self-antigens. ②Drugs and chemical reagents: some drugs can make DNA methylation decrease, thus inducing drug-related lupus. ③Microbial pathogens, etc.: they can also induce the disease. 3. Estrogen: The prevalence is significantly higher in women than in men, 9:1 in the pre-menopausal stage and 3:1 in children and the elderly. In summary, SLE is mainly caused by three etiologies: genetic, environmental and estrogenic.