For patients with known autoimmune disease, or those with positive antinuclear autoantibodies that lack a diagnosis of a particular rheumatologic condition, EXT1/2, NCAM1, and TGFBR3 staining can identify approximately 40% of cases, although our current knowledge gap of the remaining antigens still leaves the majority of SLE patients untypeable. The gene discussed is EXT1; the disease is systemic lupus erythematosus.