PON1 and systemic lupus erythematosus: In summary, our results suggest that PON2 genetic variation is significantly and independently associated with variation in serum PON activity (after incorporating effects of age, SLE status, relevant PON1 and PON3 variation), although to a much lesser extent than PON1. We found no obvious association between PON2 tagSNPs and SLE risk, however, we observed few modest associations with lupus nephritis and SLE-related immunological disorder which await replication in larger independent samples.