No association between schizophrenia and homozygosity at the D3 dopamine receptor gene

The D₃ dopamine receptor gene is an important candidate gene for schizophrenia, since (because of its almost exclusive expression in the limbic system) it combines the dopamine receptor hypothesis with the limbic system hypothesis of schizophrenia. A BalI restriction fragment length polymorphism of the D₃ dopamine receptor gene has been typed in 107 schizophrenic patients and 98 normal controls from Sichuan (China). With regard to alleles or genotypes, no significant differences were obtained between controls from Europe and China, between patients and controls, and between patient subgroups and controls. These results indicate a lack of association between schizophrenia and the D₃ dopamine receptor gene in our sample. Our findings are at variance with reports of a significant excess of homozygosity at the D₃ dopamine receptor gene in schizophrenic patients from Wales (United Kingdom) and Alsace (France). In conclusion, further studies will be needed with larger samples of patients from Wales and Alsace as well as with samples of different racial groups to prove or disprove the initial positive association between schizophrenia and genotypes of the D₃ dopamine receptor gene. © 1993 Wiley-Liss, Inc.     

No evidence of association between structural polymorphism at the dopamine D3 receptor locus and alcoholism in the Japanese

Dopaminergic systems mediate reward mechanisms and are involved in reinforcing self-administration of dependence-forming substances, including alcohol. Studies have reported that polymorphisms of the dopamine D2 receptor, whose structure and function are similar to those of the dopamine D3 receptor, increase the susceptibility to alcoholism. These observations led to the examination of the possible association between a structural polymorphism of the D3 receptor gene and alcoholism. Genotyping results, employing a PCR-RFLP method, showed no difference in allele and genotype frequencies of the D3 BalI polymorphism (Ser⁹/Gly⁹) between Japanese alcoholics and controls. Moreover, these frequencies were not altered in alcoholics with inactive aldehyde dehydrogenase-2 (ALDH2), a well-defined negative risk factor for alcoholism. These results strongly suggest that the dopamine D3 receptor is not associated with alcoholism. © 1996 Wiley-Liss, Inc.     

Trend for an association between schizophrenia and D3S1310, a marker in proximity to the dopamine D3 receptor gene

There is considerable controversy regarding a putative association between schizophrenia and a biallelic BalI polymorphism in the first exon of the dopamine D3 receptor gene (DRD3), although meta-analyses of published data suggest an association. If such an association exists, it may be detectable at markers physically close to DRD3. Accordingly, we conducted a case-control association study using D3S1310, a short tandem repeat polymorphism located approximately 700 kb telomeric to DRD3 on chromosome 3q13.3. The subjects were Swedish patients with schizophrenia (DSM III-R criteria, n = 110) and screened adult controls (n = 83). A trend for a negative association with the 141 bp allele was detected (χ² = 7.6, d.f. = 1, P = 0.006; odds ratio 0.46, 95% confidence intervals 0.26, 0.81). However, following corrections for multiple comparisons using subgroups (n = 15) the difference was not significant. Also, due to the risk for population stratification in case-control association studies the results must be treated as tentative. If replicated the results may lend further support for the proposition of an association between schizophrenia and DRD3 or a gene in close proximity to DRD3 on chromosome 3q. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:352–357, 1999. © 1999 Wiley-Liss, Inc.     

多巴胺D3受体基因Ser-9-Gly多态性精神分裂症的关联研究

为探讨精神分裂症与多巴胺 D3受体基因 ( dopamine D3receptor gene,DRD3) Ser-9-Gly多态性是否关联。应用PCR-RFLP方法检测了广州地区汉族人群中 1 2 3例家族史阴性、1 1 3例家族史阳性精神分裂症患者、1 6 8例家族史阴性患者父母和 4 7例正常老年人中多巴胺 D3受体基因 Ser-9-Gly多态性 ,并对多巴胺 D3受体基因各等位基因及基因型与精神分裂症进行了相关分析 ,DRD3与精神分裂症、患者性别及家族史均无关联 ( P>0 .0 5 )。提示广州地区汉族人群中DRD3基因 Ser-9-Gly多态性与精神分裂症没有关联。     

No association detected between a D3 receptor gene-expressed variant and schizophrenia

A missense polymorphism (glycine to serine) in the first exon of the dopamine D₃ (DRD3) gene was examined in a sib-pairs schizophrenia collection by the transmission test for linkage disequilibrium (TDT). No association due to linkage disequilibrium was detected using TDT. Additionally, no evidence for excess homozygosity was found. © 1996 Wiley-Liss, Inc.     

多巴胺受体D2型基因启动区多态性与精神分裂症关联研究

目的探讨湖北武汉地区汉族人群中多巴胺受体D2型基因(dopamine receptor D2, DRD2)启动区-141位点胞嘧啶插入/缺失多态性与精神分裂症的关联关系.方法应用聚合酶链反应-限制性片段长度多态性方法,对120例精神分裂症患者、100名健康对照者进行基因分型.对精神分裂症患者的 DRD2 -141位点胞嘧啶插入/缺失多态性进行了相关分析.结果 DRD2型基因启动区-141位点的等位基因、基因型频率在精神分裂症组与对照组之间的分布差异有统计学意义(P<0.05).在精神分裂症组中,-141C缺失的等位基因频率为0.11,对照组为0.18(比值比为0.55,95%可信区间为0.30～0.96,P <0.05).结论 -141位点胞嘧啶插入/缺失多态性非独立性地对精神分裂症与 DRD2基因的相关性产生修饰作用.-141位点胞嘧啶缺失可能是湖北武汉汉族精神分裂症患者的保护因素之一.     

Genetic association between the dopamine D3 gene polymorphism (Ser9Gly) and schizophrenia in Japanese populations: evidence from a case-control study and meta-analysis

Dysregulation in the dopaminergic system has been implicated in the pathophysiology of schizophrenia (SCZ). Dopamine D3 receptors (DRD3) concentrated in limbic regions of the brain (important for cognitive, emotional and endocrine function) may be particularly relevant to SCZ. A recent meta-analysis with mixed ethnicities reported a marginal significant association between the Ser9Gly homozygosity in the first exon of the DRD3 gene and SCZ. To further evaluate the controversial association between this polymorphism and SCZ, a case–control study and meta-analysis was conducted using the homogeneous Japanese population. In our Japanese case–control sample (246 cases/198 controls), we found an association between the DRD3 Ser9Gly polymorphism and SCZ (genotype: χ² = 9.76, d.f. = 2, p = 0.008; Ser allele versus Gly allele: χ² = 7.96, d.f. = 1, p = 0.0048; OR = 0.65; 95% CI = 0.48–0.88). However in a meta-analysis of nine Japanese case–control studies comprising 2056 subjects the association between DRD3 Ser9Gly polymorphism and SCZ did not persisted. The Mantel–Haenszel pooled OR for SCZ among carriers of the DRD3 Ser9Gly homozygosity (Ser/Ser homozygotes and Gly/Gly homozygotes) of the nine Japanese studies was 1.16 (95% CI 0.97–1.39), pointing to a non-significant effect of the DRD3 Ser9Gly homozygosity as a risk factor for SCZ. Overall, our results suggest that the DRD3 Ser9Gly polymorphism may not confer susceptibility to SCZ in the Japanese population. Given that the Ser9Gly variant may play a putative role in DRD3 function, further studies on the DRD3 with linked variants are warranted.     

No association between the dopamine D3 receptor Bal I polymorphism and schizophrenia in a family‐based study of a Palestinian Arab population

Several recent meta‐analyses appear to show a weak but significant effect of both forms of the gly/ser DRD3 polymorphism in conferring risk for schizophrenia. Since most studies have employed the artifact‐prone case‐control design, we thought it worthwhile to examine the role of this polymorphism using a robust family‐based strategy in an ethnic group not previously systematically studied in psychiatric genetics, Palestinian Arabs. We failed to obtain any evidence in 129 Palestinian triads, using the haplotype relative risk (allele frequency: Pearson chi‐square = 0.009, P > 0.1, df = 1, n = 258 alleles) or transmission disequilibrium test design (chi‐square = 0.38, P > 0.1, n = 86 families) for association/linkage (or increased homozygosity) of the DRD3 Bal I polymorphism to schizophrenia in our sample. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:778–780, 2000. © 2000 Wiley‐Liss, Inc.     

Association study between the dopamine D4 receptor gene and schizophrenia

The dopamine D4 receptor is of major interest in schizophrenia research due to its high affinity for the atypical neuroleptic cloza-pine and a high degree of variability in the receptor gene (DRD4). Although several genetic linkage analyses performed on schizophrenia multiplex families from different regions of the world have either excluded or failed to prove that DRD4 is a major genetic factor for the development of schizophrenia, analyses for moderate predisposing effects are still of significant interest. We performed a study examining differences in allele frequencies of 4 different DRD4 polymorphisms in schizophrenia patients and age, sex, and ethnic origin matched controls. None of these 4 polymorphisms showed evidence for genetic association with schizophrenia, although a trend towards excess of the allele with 7 repeats in the (48)_n bp exon III polymorphism was observed. Complexities in the DRD4 genetic investigation and further analytic approaches are discussed. © 1995 Wiley-Liss, Inc.     

No association between the Ser9Gly polymorphism of the dopamine D3 receptor gene and schizophrenia in a Spanish sample.

This study aims to further evaluate the controversial association between the Ser9Gly polymorphism in codon 9 of the D3 dopamine receptor gene (DRD3) and schizophrenia in psychiatric inpatients acutely hospitalized in two general hospitals in Madrid, Spain. The Ser9Gly polymorphism of the DRD3 was examined in 178 schizophrenic patients, 286 patients with other psychiatric diagnoses, and 132 controls recruited. Genotype frequencies were in Hardy-Weinberg equilibrium. No association was found between schizophrenia and the Ser9Gly polymorphism of the D3 dopamine receptor gene.     

Association study of dopamine D3 receptor gene and schizophrenia

Several groups have reported an association between schizophrenia and the MscI polymorphism in the first exon of the dopamine D3 receptor gene (DRD3). We studied this polymorphism using a North American sample (117 patients plus 188 controls) and an Italian sample (97 patients plus 64 controls). In the first part of the study, we compared allele frequencies of schizophrenia patients and unmatched controls and observed a significant difference in the total sample (P = 0.01). The second part of the study involved a case control approach in which each schizophrenia patient was matched to a control of the same sex, and of similar age and ethnic background. The DRD3 allele frequencies of patients and controls revealed no significant difference between the two groups in the Italian (N = 53) or the North American (N = 54) matched populations; however, when these two matched samples were combined, a significant difference was observed (P = 0.026). Our results suggest that the MscI polymorphism may be associated with schizophrenia in the populations studied. © 1995 Wiley-Liss, Inc.     

No association between a promoter dopamine D4 receptor gene variant and schizophrenia

The dopamine D₄ receptor has been implicated in the pathogenesis of schizophrenia. An association between a putative functional promoter polymorphism (?521C/T) in the dopamine D₄ receptor gene (DRD4) and schizophrenia was recently reported. In the present study, patients with schizophrenia (n = 132) and control subjects (n = 388) were analyzed with respect to the DRD4 ? 521C/T polymorphism. No significant case control differences emerged. The present results do not support a major role for DRD4 in the etiology of schizophrenia among Caucasians from Sweden. © 2001 Wiley‐Liss, Inc.     

Association between three functional polymorphisms of dopamine D2 receptor gene and tardive dyskinesia in schizophrenia

The dopamine D2 receptor (DRD2) gene is considered one of the candidate genes contributing to the development of tardive dyskinesia (TD). In the present study, we investigated the genetic association between three functional polymorphisms (Ser311Cys, ?141C Ins/Del and TaqI A) in the DRD2 gene and TD (200 patients with schizophrenia: 44 with TD and 156 without TD). No significant difference in the allelic and genotypic distribution between patients with TD and those without TD was observed. However, we found a slightly significant association between the ?141C Ins/Del polymorphism and the total Abnormal Involuntary Movement Scale (AIMS) score (P = 0.037). The significant association between the ?141C Ins/Del polymorphism and the total AIMS score did not remain after the regression analysis was taken into account (P = 0.14). Our results suggest that that three functional polymorphisms in DRD2 may not play a major role in the occurrence of TD. © 2001 Wiley‐Liss, Inc.     

Association of dopamine receptor D5 gene polymorphism with peculiarities of voluntary attention in schizophrenic patients and their relatives

We studied the relationship between DRD5 gene polymorphism presented by microsatellites with cognitive signs in 152 schizophrenic patients, 81 mentally healthy relatives, and 125 mentally healthy control individuals. An association was found between DRD5 polymorphism with efficiency of visual voluntary attention in patients (p=0.02) and their relatives (p=0.006). Carriers of two copies of the 148-b.p. allele were characterized by low efficiency of attention. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 1, pp. 71–73, January, 2008