Systemic lupus erythematosus (SLE) could have the most complicated phenotype and the most diverse genetics of any genetically complex human disease. Recent research shows that genetic ablation of the gene encoding 60kD Ro, a common autoantigen for SLE patients, results in an SLE-like illness in Ro-/- mice. These data add to the expanding cooperation between mouse and human SLE genetic studies and are the first in which ablation of an autoantigen induces an autoimmune disease.