Analysis of paraoxonase 1 (PON1) genetic polymorphisms and activities as risk factors for ischemic stroke in Turkish population

BACKGROUND: Paraoxonase1 (PON1) is protective against the development of atherosclerosis, a risk factor for ischemic stroke. PON1 gene has one promoter region (-107T/C) and two coding region (192Q/R and 55L/M) polymorphisms that affect the levels and catalytic efficiency of the enzyme, respectively. In this study, we aimed to determine the importance of -107T/C, 192Q/R and 55L/M polymorphisms of PON1 gene and three PON1 activities (diazoxonase, paraoxonase, arylesterase) as risk factors for ischemic stroke. METHODS: Study population was comprised of 172 unrelated adult Caucasian patients with acute hemispheric ischemic stroke and 105 symptom-free controls. Genotypes were attained by PCR followed by restriction enzyme digestion and phenotypes were determined by spectrophotometric assays. RESULTS: This is the first study analyzing diazoxonase activity as a risk factor for ischemic stroke. Nevertheless, diazoxonase, paraoxonase and arylesterase activities were almost the same in stroke patients and controls. The -107TT genotype was associated with a 1.97 times increased risk for stroke in elderly (age > 59). Individuals with this genotype were found to have the lowest PON1 enzyme activities among the -107T/C genotypes. Triple combined haplotype QRLMTC was found to be 6.94- and 10.4-times protective against ischemic stroke in the overall and the elderly population, respectively. 55LL genotype was associated with a 1.78-fold increase in the risk of ischemic stroke. CONCLUSION: PON1 genotypes, but not activities, are related with the risk of stroke.