C3 and systemic lupus erythematosus: The variant allele of rs6920220 showed associations only with SLE clinical phenotypes; in particular, it conferred a higher risk to develop clinical features such as pericarditis, pleurisy, and nephritis but a protective role with respect to decreased C3 and C4 levels in the clinical history, suggesting that TNFAIP3 gene may be involved in different disease pathways [28].