SERPINA1 Gene SNP Rs6647 Variant Association Study With Genetic Risk Of Large Artery Atherosclerotic Stroke

Objective:Stroke is one of the neurological diseases with the highest disability rate among the elderly.A genome-wide association study recently identified the SNP rs6647 variant G allele in SERPINA1 gene had a significant association with the large artery atherosclerotic stroke(LAS)risk.Until now,the precise regulatory mechanism by which the SNP rs6647 variant G allele increases the LAS risk remains to be determined.Methods:In this study,GWAS datasets and Genomic database were used for analysis.First,a functional annotation of the rs6647 variant was performed by using the Haplo Reg v4.1.Secondly,the expression quantitative trait loci(e QTLs)analysis based on multiple datasets(containing 56 tissues)was conducted for determining the potential association between the rs6647 and SERPINA1 expression in various tissues,the significance level is adjusted by Bonferroni method,with a threshold of 0.05/56=8.93E-04.Thirdly,two independent GEO ischaemic stroke gene expression datasets were used to carry out a case-control gene expression analysis.Fourthly,whole blood samples from 8 LAS patients and 14 healthy subjects were collected,and the expression of SERPINA1 level measured by RT-q PCR was compared between groups.Finally,we used the co-expression gene network analysis(Coexpediac)of SERPINA1 gene to analyze the co-expression genes,biological pathway and gene-disease studies of SERPINA1 gene.Results:1.The functional annotation suggested that the rs6647 regulates gene expression in multiple human tissues especially in brain and blood;the variant of SNP rs6647 is most localized in the enhancer region of primary neutrophil histone in peripheral blood and embryonic brain tissue.2.The e QTLs analysis revealed a significant association of the rs6647 G allele with increased expression of SERPINA1 gene only in whole blood.Through e QTL analysis of Braineac,it was found that the rs6647 G allele mutation was not associated with the expression of SERPINA1 and its surrounding genes in human brain tissue.It was found that in addition to the SERPINA1 gene itself,this mutation may affect the expression of other genes at and around the SERPINA1 site.The rs6647 G allele was significantly correlated with the expression of SERPINA1 gene and its surrounding IFI27L1 gene in cell_transformation_fibroblast(P=2.49E-04)and heart_left_ventricle(P=8.92E-04),while DDX24 was significantly correlated with the aorta(P=6.77E-04).SERPINA1 levels did not differ between men and women.3.We further found an increased expression of SERPINA1 gene in the whole blood samples of ischaemic stroke patients compared with the controls.4.We also found an increased expression(1.85-fold)of SERPINA1 gene in the peripheral blood of LAS patients compared with the controls.5.In the co-expression gene network analysis,we found that SERPINA1 gene and its co-expression network genes were involved in multiple pathways of inflammation and immunity and so on.Associated genes of atherosclerosis causing by SERPINA1 included HPX,ALDOB,CYP2C9,HRG,CYP2E1,ORM1 and CYP2C8,AMBP,KNG1,APOC3,etc.;This is the first study revealing the association of SERPINA1 gene with LAS and multiple diseases,we also found that SERPINA1 gene and its co-expression genes were associated with a number of chronic diseases,such as atherosclerosis,coronary heart disease,inflammation,insulin resistance,metabolic syndrome and hypertension.Conclusion:1.This study suggest that SERPINA1 gene expression in whole blood bridges the rs6647 variant G allele with increased LAS risk,providing new insights into the mechanisms underlying role of the rs6647 in increasing the LAS risk.2.The expression of SERPINA1 gene in peripheral blood of LAS patients was higher than that of healthy subjects.3.SERPINA1 is associated with atherosclerosis,inflammation and other diseases,SERPINA1 and its co-expression network gene regulate multiple biological pathways of inflammation,immunity and lipid metabolism in the body.