Abstract
Systemic Lupus Erythematosus (SLE) is defined by its clinical features and by the almost invariable presence in the blood of antibodies directed against one or more components of cell nuclei. Certain manifestations seem to be associated with the presence of different antinuclear antibodies and genetic markers, which suggests that SLE may be a family of diseases. However, clinical presentations frequently overlap, and there is currently no conclusive evidence that SLE is more than a single disorder with a broad range of manifestations, the expression of which may be influenced by the patient's genetic background. Occasionally patients have features of both . . .