Dopamine D1 receptor (DRD1) 5' region haplotypes significantly affect transcriptional activity in vitro.

The role of dopamine D1 receptor (DRD1) gene promoter polymorphisms in schizophrenia remains controversial. We aimed to characterize the polymorphisms in the promoter region because little is known about the extent of variance in this region and potential roles in gene transcription activity. In a previous case-control study, we amplified and genotyped the polymorphisms of DRD1 gene. According to its haplotype estimation, we identified eight SNPs and confirmed ten different haplotypes by cloning and sequencing the fragment spanning -1990 to +10. The promoter activity of these haplotypes was analyzed using dual luciferase assays in SH-SY5Y and HEK293 cells. Compared with the reference haplotype, the constructed haplotypes containing different variation sites could significantly alter the luciferase activity. Additionally, the prediction of the transcription factor binding sites was performed. Our examination could provide the informative reference for the role of DRD1 gene promoter in schizophrenia.