SLE and other autoimmune diseases are driven by loss of immune tolerance to “self” molecules in the body. This triggers the immune system to target parts of the body, leading to inflammation and tissue injury. There is no single, known cause for this loss of self-tolerance in SLE. Instead, a combination of internal and external factors play a role in SLE etiology, including genetic, hormonal, immunologic, and environmental determinants. For example, over 100 genetic abnormalities are associated with lupus, but unless these genes are coupled with environmental triggers (e.g., viral or bacterial illness, ultraviolet light exposure) or epigenetic changes, it is rare for SLE to occur due to genes alone.