Lack of association between Alzheimer's disease and Gln-Arg 192 Q/R polymorphism of the PON-1 gene in an Italian population

Alzheimer's disease (AD) is characterized by deposition of oxidized low-density lipoprotein (LDL) forming the senile plaque and by structural changes and cell death in acetylcholine-producing neurons. Paraoxonase-1 (PON-1) is a secreted protein primarily associated with high-density lipoproteins (HDL) and participates in the prevention of LDL oxidation. PON-1 is also an arylesterase that hydrolyzes paraoxon, an active toxic metabolite of parathion, thus providing protection against organo-phosphate poisoning and metabolization of environmental neurotoxins that might be responsible for neurodegeneration with aging. Serum levels of PON-1 are genetically determined and strongly influenced by a common polymorphism on the position 192 of the PON-1 gene. The aim of this study was to evaluate whether the polymorphism of the PON-1 gene is associated with AD. We studied 124 Italian subjects affected by probable AD and 135 age- and sex-matched controls. The distribution of PON-1 genotypes was 64 QQ, 46 QR, 14 RR in the AD patients and 57 QQ, 59 QR, 19 RR in the control subjects. No statistically significant difference was found between the two groups in our population (p = 0.130 for homozygous QQ, p = 0.279 for heterozygous QR, and p = 0.502 for homozygous RR). These results suggest that the human Gln-Arg 192 Q/R polymorphism of the PON-1 gene is not associated with AD in an Italian population. Copyright © 2003 S. Karger AG, Basel.