Association Of SNPs In The Promoter Region Of Dopamine Receptor D2 Gene With Schizophrenia And The Effect Of Promoter Polymorphisms On Gene Expression

Objective: In the northern Han nationality,there are few studies on DRD2 gene polymorphisms,and the association between these polymorphisms and the risk of schizophrenia is also rare.At present,forensic psychiatric forensic expertise lacks scientific indicators.This study explored the association between polymorphisms in the promoter region of dopamine receptor D2 gene and schizophrenia and the influence on gene expression.Methods: Venous blood samples were collected from 306 cases of schizophrenia patients and 324 cases of unrelated healthy individuals in northern China,and genomic DNA was extracted.The DRD2 promoter region was sequenced by PCR and Sanger sequencing.SPSS version 18.0 was used to calculate the odds ratio(OR)and 95% confidence interval(CIs).Haploview version 4.1 was used for Haploview equilibrium assessment and haplotype prediction.The association between risk of schizophrenia and alleles,genotypes and haplotypes was calculated by chi-square test.The expression of different polymorphisms and gene fragments in HEK-293 and SK-N-SH cell lines was determined by double luciferase reporter assay.Results: In this study,it was found that there was no statistical correlation between DRD2 gene 5 '-end SNPs and haplotypes and schizophrenia in northern Han Chinese.However,the haplotype H4 was significantly higher expressed in SK-N-SH cells than the other three cells.In HEK-293 and SK-N-SH cell lines,the recombinant vector expression of allele C of rs7116768 was significantly higher than that of allele G.In HEK-293 and SK-N-SH cell lines,the recombinant vector expression of allele A of rs1047479195 was significantly higher than that of allele C.The recombinant vector of rs1799732 allele del C was significantly enhanced in HEK-293 cell line to the allele insC.The-121~-226 bp region of the 5 '-terminal regulation region of DRD2 gene was shown to enhance relative luciferase activity in HEK-293 cell line and inhibit relative luciferase activity in SK-N-SH cell line.The-344~-468 bp region showed enhanced relative luciferase activity in HEK-293 cell lines.The-468~-539 bp region decreased relative luciferase activity in HEK-293 and SK-N-SH cell lines.The-720~-925 bp region showed enhanced relative luciferase activity in SK-N-SH cell lines.The-1234~-1363 bp region decreased relative luciferase activity in HEK-293 and SK-N-SH cell lines.The-1363~-1457 bp region showed enhanced relative luciferase activity in HEK-293 cell lines.The-1457~-1549 bp region inhibited relative luciferase activity in HEK-293 cell lines and enhanced relative luciferase activity in SK-N-SH cell lines.The-1549~-1649 bp region showed enhanced relative luciferase activity in HEK-293 cell lines.Conclusion: In this study,we found that SNPs in the 5 '-end regulation region of DRD2 gene,haplotypes and different regional fragments may lead to the occurrence of schizophrenia by changing the gene expression.There are 5~7 functional regions in 5 '-end of DRD2 gene which can change the gene expression.