Gene Polymorphisms In The Transcription Regulatory Region Of Alox5Ap Gene And Susceptibility Of Ischemic Stroke In Henan Han Population

Background and Aims:Ischemic stroke (IS) is a complex multifactorial disorder and several environmental and genetic risk factors contribute to it. Inflammation has emerged as a key element in all critical steps of atherosclerosis, which underlies the pathogenesis of cardiovascular disease and ischemic stroke.In2004, deCODE Study Group firstly reported ALOX5AP gene as an independent risk factor of ischemic stroke by genome-wide screening in Icelandic population. The ALOX5AP gene encodes5-lipoxygenase activating protein (FLAP), which plays an essential role in the transfer of arachidonic acid to Leukotriene (LT). LT has affect the process of atherosclerosis because of leading to many pathological mechanisms, such as leukocyte activation, promoting the adhesion of monocytes and vascular wall, increasing the permeability of the blood vessel wall and so on. Recently, the data of animal models and clinical research revealed that FLAP was closely related to the occurrence of LT, which affected the process of ischemic stroke.However, the researchers did not find any SNP that caused amino acid change in ALOX5AP gene. Maybe the effect of ALOX5AP gene on ischemic stroke existed in the level of transcriptional regulation.Thus, our study selected ALOX5AP rs17222919which located in the promoter and rs9579646which located in the first intron, TaqMan-PCR technology was adopted to detect the polymorphisms of the two SNPs on810IS patients and825collator, in order to further explore the relationships between the two SNPs and ischemic stroke in Henan Han population.Study population:810cases as patient group with ischemic stroke in departments of neurology in Henan province hospitals were enrolled from March2008to November2010. There were416male and394female with an average of56.1±10.6years. All patients had clinically relevant investigations performed, including brain imaging with CT or/and MRI as well as ancillary diagnostic investigations and standardized blood tests. The patients in case group were divided into three subtypes according to the TOAST classification of IS:large artery atherosclerosis stroke (616cases), small-artery occlusion Lacunar (78cases) and ischemic stroke of other undetermined etiology (116cases).825unrelated heathy controls were selected from subjects in outpatient department who underwent regular check-up examination.428of them were male and397were female with an averageof55.3±10.3years. All of them were Henan Han population. Signed consent form was obtained from each participant. The study protocols were approved by the Ethics Committee on Human Research of Zhengzhou University.Methods:Genomic DNA was extracted by phenol-chloroform extraction method and its content was determined by the amount of nucleic acid protein analyzer. Genotyping was performed by using the TaqMan-PCR technology, and the genotyping results were verified by sequencing.All statistical procedures were performed with SPSS19.0software package. The frequence of the alleles and genotypes between IS group and control group were counted and compared by the Chi-square test. Hardy-weinberg equilibrium、 Haplotype、Linkage disequilibrium were analysed with SHEsis software. Odds ratio with95%confidence intervals (95%CI) were calculated to test the association between risk factors and IS. The interaction between gene mutation and environmental factors were evaluated by Logistic regression models. P value<0.05was taken as statistical significant.Results:1. The rs17222919TG、GG genotype frequencies and G allele frequencies between IS group and control group existed strong difference (P<0.05),and the association between rs17222919and IS was found especially in autosomal dominant mode.2. The rs9579646GG genotype frequencies of SAA group had2.317times higher than those of control group (OR=2.317,95%CI:1.100-4.882), and G allele frequencies of SAA group had1.474times higher than those of control group (OR=1.474,95%CI:1.052-2.066); The rs17222919GG genotype frequencies of LAA group had significantly lower than those of control group (OR=0.519,95%CI:0.295-0.914), and TG genotype frequencies of SUE group had significantly lower than those of control group (OR=0.554,95%CI:0.352-0.870).3. In accordance with the sex and age classification analysis, the rs17222919GG genotype frequencies of male group and younger than50years old had significantly lower than those of control group (OR＝0.443,95%CI:0.207-0.949;OR=0.312,95%CI:0.116-0.840); the rs17222919TG genotype frequencies and G allele frequencies of female group and more than50years of age had significantly lower than those of control group (OR=0.602,95%CI:0.446-0.812;OR=0.679,95%CI:0.548-0.886)&(OR＝0.727,95%CI:0.562-0.941; OR=0.796,95%CI:0.646-0.982)4. The interaction existed in rs17222919TG+GG genotype and hypertension、 diabetes、alcohol smoking, all showing the negative interaction.5. Haplotype analysis showed that, A-G、A-T、G-G haplotypes between IS group and controls group exist significantly differences. A-G haplotypes showed a significant protective effect for IS (OR=0.712,95%CI:0.598-0.848),but A-T、 G-G haplotypes showed a significant risk effect for IS (OR=1.281,95%CI:1.100-1.495; OR=2.229,95%CI:1.288-3.857)Conclusions:1. There may be an association between the ALOX5AP rs17222919and ischemic stroke, and GG genotype may be genetic protective factor for LAA, TG genotype may be genetic protective factor for SUE. TG+GG genotype can reduce risks of IS in subjects with hypertension diabetes or alcohol smoking.2. The G allele and GG genotype of rs9579646may be genetic risk factor of SAA.3. A-T、G-G haplotype maybe increased the risk of IS, but A-G haplotype had protective effect against IS in Henan Han population.