The Arg allele in position 192 of PON1 is associated with carotid atherosclerosis in subjects with elevated HDLs.

Human serum paraoxonase (PON1) is an HDL-associated enzyme involved in the protection of lipoproteins from oxidation. A polymorphism at position 192 (Gln/Arg) influences its activity in a substrate-dependent manner. The aim of the present study was to evaluate, in vivo, the contribution of the PON1-192 polymorphism to the protective effect of HDLs.