We report a case of a patient with systemic lupus erythematosus (SLE) who presented with encephalopathy and was subsequently diagnosed with thrombotic thrombocytopenic purpura (TTP) based on ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin motifs 13) deficiency. This evidence concerns the gene ADAMTS13 and thrombotic thrombocytopenic purpura.