| Stroke, a common neurological disease featured by high incidence, morbidityand mortality, can bring severe harm to human health. Thus it has become a leadingcause of morbidity and mortality in both urban and rural Chinese areas. Ischemicstroke (IS) with an atherosclerotic trigger boasts an increasingly high incidence,accounting for80%or so of all the strokes. It has been reported that risk factors suchas hypertension, diabetes, obesity, smoking, dyslipidemia, sex and age, etc. are tightlyassociated with IS. However, risk factors can explain only part of the pathogenesisand genetic variations also play vital roles in the development of IS. IS, a complexmultifactorial and polygenetic disorder of genetic heterogeneity, is the result ofmutual interaction between individual’s genetic background and variousenvironmental factors. Considerable genetic epidemiological studies about differentraces, especially those about candidate genes and candidate pathway, have identifiedmany predisposing genes that are associated with IS risk including those in theleukotrienes (LTs) biosynthesis pathway.Given that vascular inflammation has been recognized as an importantmechanism of atherosclerotic disease, expressions of proinflammatory genes may play pivotal parts in the pathogenesis of IS. LTs biosynthesis pathway, consisting of afamily of arachidonic acid metabolites, makes a positive contribution to inflammatorydiseases involving atherosclerosis. Genetic variations in the members of LTs pathwaycan increase susceptibility to IS by promoting the development of atherosclerosis.Since a study conducted by the deCODE group suggested that genetic variants inALOX5AP gene and LTA4H gene in LTs pathway conferred higher risk of IS, severalgroups attempted to replicate the association of IS with genetic polymorphisms in LTspathway. Genetic association studies in different populations were subsequentlycarried out. However, the results were controversial and conflicting. Moreover, thecurrent case-control studies were mainly about single gene and single locus and rarewere in regard with interactions between relevant genes in LTs pathway and nonewere concerned with that interactions in Chinese population.The present study selected LTs biosynthesis pathway as its candidate pathwayand genes encoding key enzymes and proteins in this pathway as its candidate genes.Case-control association study was conducted so that relationship between geneticpolymorphisms and IS susceptibility in Eastern Han Chinese can be analyzed on themolecular level. Since it was not only a single gene and single single nucleotidepolymorphism (SNP) locus analysis but also an interaction analysis of distinct genesin this pathway, the present study reported the role of genetic polymorphisms in ISpathogenesis from the perspective of gene-gene interactions, so that it can providereference for the relevant genetic study in Eastern Han Chinese about the humangenome epidemiology and meanwhile make a scientific contribution to the furtherresearch of IS genetic etiology as well as the individual-specific IS prevention andtreatment.[Objective] This study was aimed to explore the association of geneticpolymorphisms in the members of the LTs biosynthesis pathway and its interactions with IS susceptibility in Eastern Han Chinese.[Methods] A case-control study was conducted with a total of690unrelated patientsthat were clinically diagnosed IS and a control group of767non-stroke individuals.All subjects were genetically-unrelated Eastern Han Chinese (mainly from Jiangsuand Anhui provinces) and recruited from the First Affiliated Hospital of NanjingMedical University (Nanjing) from January2009to January2011under a strictinclusion criterion. Carefully designed structural questionnaires of epidemiology weredistributed among them and the relevant clinical indexes, blood samples and genomeDNA were collected. Five polymorphisms loci were selected in four genes i.e.ALOX5AP, ALOX5, LTA4H, and LTC4S gene that encode key enzymes and proteinsin LTs pathway. And with tight quality supervision, PCR-PIRA (primer introducedrestriction analysis) was used to identify primer and incision enzymes and PCR-RFLP(restriction fragment length polymorphism) to genotype and detect the relevant SNPsloci. Apart from that, combined methods including single locus analysis andinteraction analysis of multiple genes and loci were employed to explore the effect ofgenetic variations in LTs biosynthesis pathway on IS risk.[Results]1. Clinical characteristics of subjectsThe present study finished a complete and thorough epidemiology and genotypeinvestigation in690IS cases and a control group of767subjects. The mean age was67.87±9.52for the cases and67.54±9.46for the controls respectively with nostatistically significant difference between the two groups (P=0.504). However, IScases had a higher prevalence of conventional risk factors including sex (male),smoking, hypertension and diabetes and were significantly distinct from the controls(P <0.05). Meanwhile, average clinical indexes such as BMI, SBP, DBP, FPG, TC,TG, LDL-C, UA, and Lp(a) were significantly higher (P <0.01) in IS cases than that in controls while the average HDL-C were lower in IS cases than that in controls.2. Single-locus analysisIn loci of ALOX5rs2029253A>G and LTC4S rs730012A>C, the frequencies ofthree genotypes in the case and control groups were significantly different (P=0.005and0.025, respectively). In locus LTC4S rs730012A>C, the frequency of C allele inIS cases was higher than that in controls (13.1%vs.10.6%, P=0.033) and carriers ofC allele were more susceptible to IS than those of A allele (OR=1.28，95%CI1.02-1.60). There was no significant difference between the two groups in genotypicdistributions and in allelic frequencies of other genes in the LTs pathway (P>0.05).Multivariable Logistic regression analysis adjusted for age, sex, BMI, smoking,hypertension and diabetes was performed under recessive genetic model and itsuggested that ALOX5rs2029253A>G variant bore a negative association with ISsusceptibility (OR=0.78,95%CI0.60-1.00, P=0.048) while LTA4H rs6538697T>C and LTC4S rs730012A>C variants had increased risk of IS (OR=1.66,95%CI1.04-2.64, P=0.032and OR=3.63,95%CI1.01-13.05, P=0.048, respectively).Genetic polymorphisms of ALOX5AP rs10507391A>T and rs12429692A>T showedno significant association with IS risk (P>0.05).3. Combined analysis of multiple genes and lociIndividuals carrying the combination of three genetic risk factors, i.e. ALOX5APrs12429692T allele, ALOX5rs2029253A allele, and LTA4H rs6538697C allele hadan significantly increased susceptibility to IS (adjusted OR=1.79,95%CI1.07-2.08,P=0.026). Besides, the combined interaction effects of ALOX5AP rs12429692TT,ALOX5rs2029253AA/AG, and LTA4H rs6538697TC denoted a significantinfluence on IS susceptibility (adjusted OR=2.67,95%CI1.14-6.25, P=0.024).[Conclusion] Genetic polymorphisms in members of the LTs biosynthesis pathwayand its gene-gene interactions may exert an influence on the IS risk in Eastern Han Chinese. The present study provided experimental support in expounding the fact thatthe genetic polymorphisms interactions can affect the risk of complex diseases and itis expected that further studies about other populations can confirm the effect of thisinteractions on IS susceptibility. |
PDF Full Text Request