Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by production of autoantibodies against nuclear, cytoplasmic, and cell surface molecules that transcend organ-specific boundaries. Tissue deposition of antibodies or immune complexes induces inflammation and subsequent injury of multiple organs and finally results in clinical manifestations of SLE, including glomerulonephritis, dermatitis, thrombosis, vasculitis, seizures, and arthritis. Evidence strongly suggests the involvement of genetic components in SLE susceptibility (summary by Oishi et al., 2008). Genetic Heterogeneity of Systemic Lupus Erythematosus An autosomal recessive form of systemic lupus erythematosus (SLEB16; 614420) is caused by mutation in the DNASE1L3 gene (602244) on chromosome 3p14.3. An X-linked dominant form of SLE (SLEB17; 301080) is caused by heterozygous mutation in the TLR7 gene (300365) on chromosome Xp22. See MAPPING and MOLECULAR GENETICS sections for a discussion of genetic heterogeneity of susceptibility to SLE.