CR2 is a membrane glycoprotein that binds to the degradation debris of C3 and plays critical roles in relaying immune signals such as activating B cells via cooperating with the B cell receptors.403,405 Genetic defects in CR2 may lead to impaired debris clearance ability and abnormal B cell signaling, which are both promotive on SLE activity. The gene discussed is CR2; the disease is systemic lupus erythematosus.