PON2 is a positional candidate for SLE risk as the entire PON locus comprising three genes (PON1, PON2 and PON3) on chromosome 7q21.3 lies close to a linkage peak for SLE (LOD score of 2.40) in the same region (7q21-22) [10,11]. Here, PON3 is linked to systemic lupus erythematosus.