Dopamine receptor D2 -141C Insertion/Deletion polymorphism in a Finnish population with schizophrenia

Associations of CALM1 and DRD1 polymorphisms, and their expression levels, with Taihang chicken egg-production traits

Egg production by hens is an important reproductive performance index in the poultry industry. To investigate the effects of the CALM1 and DRD1 genes on egg production in chicken, their mRNA expression and single nucleotide polymorphisms (SNP) levels were investigated, and bioinformatics and egg-production association analyses were performed. Three SNPs (g.44069941G > A and g.44069889A > G in CALM1 and g.10742639C > T in DRD1) were detected in the exons and introns of CALM1 and DRD1 in 400 Taihang chickens. Among them, g.44069941G > A was significantly associated with Taihang chicken egg production on the 500th day (p < 0.05), whereas g.10742639C > T was significantly associated with the 300th day (p < 0.05). The expression levels of CALM1 and DRD1 in ovarian tissues of a high-yielding Taihang group were greater than in a low-yielding group (p < 0.05). The bioinformatics analysis revealed that the mutations influenced the mRNA secondary structures of CALM1 and DRD1. This study provides new insights into the potential effects of CALM1 and DRD1 polymorphisms on chicken egg production. The two SNPs g.44069941G > A and g.10742639C > T are potential molecular markers for improving the reproductive traits of Taihang chicken.

Associations between dopamine D2 receptor gene polymorphisms and schizophrenia risk: a PRISMA compliant meta-analysis

OBJECTIVE

To determine the relationships between dopamine D2 receptor gene polymorphisms and the risk of schizophrenia using meta-analysis.

METHOD

The PubMed, Embase, and China National Knowledge Infrastructure databases were searched to identify relevant literature published up to February 2016. The allele contrast model was used. Stata software was used for statistical analysis, with odds ratios (ORs) and 95% confidence intervals (CIs) calculated to evaluate the associations between dopamine D2 receptor gene polymorphisms and the risk of schizophrenia. Meta-regression and publication bias, trim-and-fill, subgroup, sensitivity, cumulative, and fail-safe number analyses were also performed.

RESULTS

This meta-analysis included 81 studies. The rs1801028 and rs1799732 were associated with schizophrenia risk among Asians (P=0.04, OR =1.25, 95% CI =1.01-1.55; P<0.01, OR =0.76, 95% CI =0.63-0.92, respectively), while the rs6277 was associated with schizophrenia risk in Caucasians (P<0.01, OR=0.72, 95% CI =0.66-0.79). The rs1800497 was also associated with schizophrenia risk in population-based controls (P<0.01, OR =0.84, 95% CI =0.72-0.97). The rs6275, rs1079597, and rs1800498 were not associated with schizophrenia risk. In addition, meta-regression indicated that the controls may be sources of heterogeneity for the rs1801028 single-nucleotide polymorphism (SNP), while ethnicity may be sources of heterogeneity for the rs6277 SNP. Publication bias was significant for the rs1801028 SNP, and this result changed after the publication bias was adjusted using the trim-and-fill method.

CONCLUSION

This meta-analysis demonstrated that the rs1801028 may be a risk factor for susceptibility to schizophrenia among Asians, while the rs1799732 may be a protective factor for that population. Large-sample studies are necessary to verify the results of this meta-analysis.

The role of C957T, TaqI and Ser311Cys polymorphisms of the DRD2 gene in schizophrenia: systematic review and meta-analysis

Background

The association between the dopamine D2 receptor (DRD2) gene and schizophrenia has been studied though no conclusive outcomes have been attained. The aim of this study was to perform a systematic review and meta-analysis to explore the relation between three polymorphisms of the DRD2 gene (C957T, TaqI and Ser311Cys) and schizophrenia.

Methods

The search was made in PubMed and EBSCO databases (up to February 2016). The systematic review included 34 case–control association studies (34 for C957T, 16 for TaqI and 36 for Ser311Cys). The association analysis comprised the allelic, additive, dominant, and recessive genetic models. The meta-analysis was performed following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement.

Results

The meta-analysis showed that TaqI (additive model: OR 0.57, 95% CI 0.30–1.14) and C957T (additive model: OR 0.75, 95% OR 0.58–0.97, recessive model: OR 0.79, 95% CI 0.64–0.98) exert a protective effect against developing schizophrenia. However, the sub-analysis for the C957T variant showed that this polymorphism exhibits a risk factor effect on Chinese individuals (allelic model: OR 1.33, 95% CI 1.04–1.70).

Conclusion

Our meta-analysis suggests an association of the DRD2 gene and the risk for schizophrenia, given that TaqI and C957T polymorphisms presented a protective effect against schizophrenia, and in the sub-analyses the C957T variant increased the risk for this disorder in the Chinese population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12993-016-0114-z) contains supplementary material, which is available to authorized users.

-141C insertion/deletion polymorphism of the dopamine D2 receptor gene is associated with schizophrenia in Chinese Han population: Evidence from an ethnic group-specific meta-analysis

Accumulate evidence has implicated dopamine D2 receptor gene polymorphisms in the etiology of schizophrenia. A single nucleotide polymorphism, -141C insertion/deletion (Ins/Del) (rs1799732), in the promoter region of the dopamine D2 receptor gene has been linked to schizophrenia; however, the data are inconclusive. This study investigated whether the -141C polymorphism is associated with the risk of schizophrenia in different ethnic groups by performing a meta-analysis. A total of 24 case-control studies examining the association between -141C Ins/Del polymorphism and schizophrenia were identified according to established inclusion criteria. Significant association was revealed between -141C Ins/Del polymorphism and schizophrenia risk in dominant genetic model (Ins/Ins + Ins/Del versus Del/Del) (odds ratio = 0.33, 95% confidence interval = 0.14-0.81, z = 2.41, P = 0.02) in Chinese Han but not in Caucasian, Japanese or India populations. Our results indicate that -141C Ins/Del polymorphism might be a susceptibility factor for schizophrenia in Chinese Han population.

The -141C Ins/Del and Taq1A polymorphism in the dopamine D2 receptor gene may confer susceptibility to schizophrenia in Asian populations

It has been reported that two single nucleotide polymorphisms (SNP) Taq1A and -141C Ins/Del in the DRD2 gene may be associated with susceptibility to schizophrenia. Due to inconclusive and mixed results, a meta-analysis was conducted to further clarify the relationship between the two SNP and schizophrenia susceptibility. A systematic literature search for the association of these two SNP with schizophrenia susceptibility was conducted using PubMed, ScienceDirect, Chinese Biomedical Literature Database, and Chinese National Knowledge Infrastructure. Odds ratios (OR) with 95% confidence intervals (CI) were used to assess the strength of the associations reported. A total of 5558 schizophrenic patients and 6792 healthy controls from 31 articles were included in this study. Evidence regarding the association between -141C Ins/Del polymorphism and schizophrenia was found in the allele frequency comparison (Ins versus Del: OR 1.29, 95% CI 1.06-1.57; p=0.01, Praw=0.1, PFalse Discovery Rate=0.023). In ethnic subgroup analysis, the result revealed that the 141C Ins/Del polymorphism was associated with schizophrenia in all genetic models in Asians, but not in Caucasians. For Taq1A polymorphism, a significant association was found in the allele frequency (A1 versus A2: OR 0.71, 95% CI 0.52-0.98, p=0.03). Stratification by ethnicity indicated an association between the Taq1A polymorphism and schizophrenia in Asians, but not Caucasians. The present study suggests that the -141C Ins/Del polymorphism carries a significantly increased risk of schizophrenia, while the Taq1A polymorphism carries a significantly decreased risk of schizophrenia susceptibility in Asians.

Association between DRD2 (rs1799732 and rs1801028) and ANKK1 (rs1800497) polymorphisms and schizophrenia: a meta-analysis

The role of dopamine D2 receptor (DRD2) polymorphisms in schizophrenia remains controversial. We performed a meta-analysis to determine whether DRD2 polymorphisms influence the risk of schizophrenia and examined the relationship between rs1799732, rs1801028, and rs1800rs028 an23381d rs1800497 genetic variants and the etiology of schizophrenia. Relevant case-control studies were retrieved by database searches and selected according to established inclusion criteria. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the associations. Meta-regression, subgroup analysis, sensitivity analysis, and cumulative meta-analysis were performed. A total of 76 studies with 16096 cases and 18965 controls were included. Specifically, 24 studies with 6075 cases and 6643 controls involved rs1799732, 36 studies with 8043 cases and 10194 controls involved rs1801028 and 16 studies with 1978 cases and 2128 controls involved rs1800497. No significant associations were observed between rs1799732 and rs1800rs732 and rs1800497 and schizophrenia. The rs1801028 locus was associated with schizophrenia, with a pooled OR of 1.221 (95% CI = 1.037-1.438, P = 0.016). This meta-analysis indicates that the rs1801028 locus may be associated with schizophrenia. These data provide possible references for future case-control studies related to schizophrenia.

Genetic polymorphisms in the dopamine-2 receptor (DRD2), dopamine-3 receptor (DRD3), and dopamine transporter (SLC6A3) genes in schizophrenia: Data from an association study

OBJECTIVE

To investigate the association between dopaminergic polymorphisms [DRD2 -141C Ins/Del, DRD3 Ser9Gly, and SLC6A3 VNTR] and schizophrenia.

METHODS

Two hundred and eighty-eight outpatients with schizophrenia (DSM-IV criteria) [mean age (SD)=36.4 (12.4), 60.1% males] and 421 unrelated healthy controls [mean age (SD)=40.6 (11.3), 51.3% males] from a homogeneous Spanish Caucasian population were genotyped using standard methods.

RESULTS

There was a significant difference in genotype distribution for the DRD2 -141C Ins/Del polymorphism [(chi(2) (2)=12.35, corrected p=0.012]. The -141C Del allele was more common in patients than in controls [0.19 vs. 0.13; chi(2) (1)=9.14, corrected p=0.018, OR (95% CI)=1.57 (1.17-2.10)]. Genotype and allele distributions for DRD3 Ser9Gly and SLC6A3 VNTR polymorphisms were similar in both groups. However, there was tentative evidence of an interaction effect between DRD3 Ser9Gly and SLC6A3 VNTR [Wald=9.56 (4), p=0.049]. Compared to the SLC6A3 10/10 genotype category, the risk of schizophrenia was halved among those with 9/10 [OR=0.51 (95% CI=0.30-0.89), p=0.017]. This protective effect was only present in combination with DRD3 Ser/Ser genotype because of the significant interaction between 9/10 and both Ser/Gly [OR=2.45 (95% CI=1.16-5.17), p=0.019] and Gly/Gly [OR=3.80 (95% CI=1.24-11.63), p=0.019].

CONCLUSIONS

This study provides evidence that a genetic variant in the DRD2 gene and possible interaction between DRD3 and SLC6A3 genes are associated with schizophrenia. These findings warrant examination in replication studies.

Association between the DRD2-141C Insertion/Deletion polymorphism and schizophrenia

Epidemiological studies have demonstrated that the genetic component is an important risk factor for the development of schizophrenia. The genes that codify the different compounds of the dopaminergic system have created interest for molecular investigations in patients with schizophrenia because the antipsychotic drugs, especially those of first generation, act on this cerebral system. Thus the aim of the present study was to investigate the possible association between the -141 Ins/Del (rs1799732) polymorphism of the dopamine receptor type 2 (DRD2) and schizophrenia. The distribution of the alleles and genotypes of the studied polymorphism was investigated in a sample of 229 patients and 733 controls. There were statistical differences in the allelic (χ2=9.78; p=0.001) and genotypic genotypic (χ2=12.74; p=0.001) distributions between patients and controls. Thus the -141C Ins/Del polymorphism of the DRD2 gene (allele Ins) was associated to the SCZ phenotype in the investigated sample.

A dopamine D2 receptor gene-related polymorphism is associated with schizophrenia in a Spanish population isolate

Numerous lines of evidence have highlighted the involvement of the dopamine system in the pathophysiology of schizophrenia. Association studies of dopaminergic genes such as the dopamine D2 receptor gene (DRD2), however, have produced contradictory results. To test the hypothesis that DRD2 polymorphisms are associated with schizophrenia, we investigated two DRD2-related polymorphisms (TaqI A1/A2 or rs1800497 and -141-C Ins/Del or rs1799732) in a Spanish population isolate from northern Spain consisting of 165 controls and 119 patients with schizophrenia. The TaqI A1 allele was less frequent in schizophrenic patients than in controls (P=0.002). A similar association was found for the TaqI A2/A2 genotype (P=0.0003). No association was found for the DRD2 -141-C Ins/Del polymorphism. The strong association between a potentially functional polymorphism, downstream of the DRD2 gene and schizophrenia, suggests that the direct or indirect functional effects of this polymorphism, acting on either the ANKK1 or DRD2 genes, may play a role in the pathophysiology of schizophrenia.