Updated assessment of the prevalence, spectrum and case definition of autoimmune disease

► The spectrum of autoimmune disease includes 81 disorders. ► Over half of the autoimmune diseases are rare (<1/104). ► Repeat and coiled-coil domains are common features of autoantigens. ► Autoimmunity sometimes phenocopies diseases due to mutations of putative autoantigens. ► Female bias is most obvious among high-prevalence autoimmune diseases.