Molecular Epidemiological Study On ALOX5 Gene And LTA4H Gene And Risk Of Stroke In Eastern Chinese Han Population

Stroke is an important health problem worldwide, and it is still a leading cause of mortality and morbidity in Chinese. It has been established that the underlying pathogenesis is likely to be mediated by both genetic and environmental risk factors.Leukotrienes has play an important role for the progression of atherosclerosis, which is a chronic inflammatory disease that underlies the pathogenesis of cardiovascular disease and stroke . Whereas the synthesis of proinflammatory leukotrienes is mediated by 5-lipoxygenase (ALOX5), the protein encoded by the ALOX5 gene and leukotriene A4 hydrolase (LTA4H), the protein encoded by the LTA4H gene.The ALOX5 and LTA4H was required for leukotriene biosynthesis, and could play an essential role in the transfer of arachidonic acid to leukotriene. The human ALOX5 gene is mapped to chromosome 10q11.2 and consists of fourteen exons. The human LTA4H gene is mapped to chromosome 12q22 and consists of nineteen exons. Based on its important physiological functions, ALOX5 and LTA4H can be considered good candidate genes for stroke risk. To date, the association between genetic variations in the ALOX5 and LTA4H gene and risk of stroke in Eastern Chinese population has not been reported. The SNP(single nucleotide polymorphism) is the polymorphism of DNA caused by a single nucleotide sequence variation on the level of genome. SNP is one of the most common autogenous variations and accounts for more than 90% of foregone polymorphisms. In the present study, we selected 4 SNPs in ALOX5 gene and 5 SNPs in LTA4H gene from the data for Chinese in the HapMap to investigate the association between common genetic variants across ALOX5 gene and LTA4H gene sequence and risk of stroke in our ongoing hospital-based case–control study in an Eastern Chinese Han population.[Objective] The aim of the present study is to investigate the association between the ALOX5 gene and LTA4H gene polymorphism and stroke in Eastern Chinese in a haplotype-based analysis.[Methods] We recruited only patients with one of three subtypes of stroke: cerebral thrombosis(thrombosis), lacunar infarction(lacunar), and intracerebral hemorrhage(hemorrhage). Those cases who had other types of stroke (transient ischemic attack, subarachnoid hemorrhage, embolic brain infarction, brain tumors, and cerebrovascular malformation) and severe systemic diseases (collagenosis, endocrine, and metabolic disease (except for diabetes mellitus, DM), inflammation, neoplastic, or renal diseases) were excluded. Diagnosis of stroke was based on the results of strict neurological examination—CT, MRI, or both—according to the International Classification of Diseases, tenth Revision (ICD-10). Controls were selected simultaneously from the same demographic area and frequency-matched to the cases by age, sex. We conducted a comprehensive association study of 691 stroke patients and 732 controls to assess the associations between the ALOX5 gene and LTA4H gene polymorphism (SNPs) and stroke risk. Genotyping was performed by using the PCR-RFLP assay. [Results]1.Basic characteristics of the subjectsThe mean age was 66.28±10.50 years for the cases and 65.51±8.94 years for the controls (P= 0.131); (61.3%) cases and (64.9%) controls were male (0.226). There was no significant difference in the distribution of age and sex between the cases and controls. As expected, cases had a higher prevalence of conventional risk factors for vascular disease, including BMI, family history of CVD, self-history of CAD, hypertension and DM, higher blood pressure, glucose, TG, TC and lower level of HDL cholesterol. However, some risk factors did not differ. For example, smoking and alcohol intake were not statistically significant (P=0.403 and P=0.319, respectively) between our two groups. Interestingly, we found either white blood count or neutrophil ratio in first time test of blood routine levels were significantly higher in overall stroke cases than in controls (P<0.001, both).2.Individual SNP association analysisFor all SNPs, We observed that two SNPs showed significant difference in the point estimate and the variance of the ORs between the cases and controls, rs6538697 (P=0.022) in LTA4H and rs2029253 (P=0.030) in ALOX5.`For rs6538697, Multivariate logistic regression analysis revealed that homozygotic type CC genotype had a increased risk of stroke (adjusted OR, 1.75; 95% CI, 1.09-2.82), compared with the wild type TT and heterozygous type TC. When stratification analyses were performed according to the gender, age, BMI, CAD history, hypertension history and DM history, rs6538697 CC genotype showed a significant detrimental effect in the subjects of male, no history of heart disease, no history of hypertension or no history of diabetes. For rs2029253, Multivariate logistic regression analysis revealed that GG genotype had a decreased risk of stroke (adjusted OR, 0.76; 95% CI, 0.59-0.97), compared with the wild type AA and heterozygous type AG. After fully adjusted, rs2029253 CC genotype showed a significant protective effect.[Conclusion] Our findings suggested that LTA4H rs6538697 and ALOX5 rs2029253 polymorphism may contribute to stroke susceptibility in Eastern China. Larger studies and functional studies are needed to confirm our findings.