Family-based association study of the serotonin-2A receptor gene (5-HT2A) and bipolar disorder

Objectives: The serotonin 2A receptor gene (5-HT2A) is of great interest for research in neuropsychiatric disorders based on the observation that various neuroleptic agents and antidepressants bind with relatively high affinity at 5-HT2A receptors, and the fact that the receptor density in platelets tends to increase in depression. To test for the presence of association between 5-HT2A and bipolar disorder (BP), we studied a large number of triad families having probands affected with DSM-IV bipolar I (BPI), bipolar II (BPII) or schizoaffective disorder, bipolar type. Methods: Two polymorphisms of 5-HT2A, 102T/C, and His452Tyr were analyzed in the 274 bipolar triad families. Both the transmission disequilibrium test (TDT) and haplotype TDT were performed on the genotype data. We also calculated the maternal transmission and paternal transmission for each allele and compared the mean ages of onset across probands grouped by genotype at each of the two markers. Results: No significant transmission disequilibrium between the alleles of 5-HT2A and BP was found. Separate studies of the sub-phenotypes also failed to demonstrate significant association. However, we found a trend towards transmission disequilibrium with the haplotype 102C.His452 (p=0.0504). This trend may become more significant with a larger sample size. Significance: At present, results of this study suggest that the 5-HT2A is unlikely to play a major role in the genetic susceptibility to BP. Future studies will be directed towards increasing sample size, focusing on subtypes of BP or biochemical measures as phenotypes, and investigating other polymorphisms of 5-HT2A to provide more information at the DNA level.     

A preliminary report of the dopamine receptor D4 and the dopamine transporter 1 gene polymorphism and its association with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent childhood-onset psychiatric syndromes affecting 5%–10% of school-age children worldwide. Distortions in the catecholaminergic system seem to be responsible for this condition. Within this system there are several candidate genes, the dopamine receptor D₄ (DRD4) and the dopamine transporter 1 (DAT1), with common polymorphism which might be associated with ADHD. We performed a family based association study with 36 trios and 19 parent proband pairs. All diagnoses were confirmed by the “Hypescheme” diagnostic computer program. In this study we did not observe an association of ADHD with DRD4 and DAT1 polymorphism neither by the haplotype relative risk (HRR) method nor by the transmission disequilibrium test (TdT) method. The odds ratio for the DRD4 7-allele was 1.01 and 0.94 for both statistical tests, respectively, and the respective odds ratio for the DAT1 6-allele were 0.91 and 0.88.     

双相情感障碍与DRD3、DRD2和COMT基因多态性的关联分析

目的　探索多巴胺D3受体 (DRD3)、多巴胺D2受体 (DRD2 )和儿茶酚氧位甲基转移酶 (COMT)基因多态性与双相情感障碍的关系。方法　使用病例 对照的关联分析方法 ,对 10 5名双相情感障碍患者和 12 8名对照者之DRD3、DRD2和COMT的多态性进行检测 ,并进行关联分析。结果　DRD3等位基因在两组间的分布有显著性差异 (χ2 =5 77,P =0 0 2 ) ,Logistic多元回归分析发现基因型 1/ 1和 2 / 2在两组间分布的有显著性差异 (P =0 0 36 ,OR=5 72 7) ,等位基因分析也有显著性差异 (P =0 0 2 2 ,OR =6 786 ) ;DRD2和COMT基因型和等位基因的分布在两组间无显著性差异 (χ2 =1 983,P =0 37/ χ2 =1 6 7,P =0 4 1;χ2 =0 2 16 ,P >0 0 5 / χ2 =0 14 3,P >0 0 5 ) ;将DRD3和DRD2共同分析时发现OR值升高 (OR =6 6 97)。结论　DRD3基因多态性与双相情感障碍有关联 ,且与DRD2有协同作用。     

Lack of association between schizophrenia and alleles in the dopamine D3 receptor gene

Dopamine receptor dysfunction has been implicated in the pathophysiology of schizophrenia. Schizophrenic patients (n= 76) and control subjects (n= 53) were examined for allele frequencies in a 2-allele BalI polymorphism, causing a serine → glycine amino acid substitution in the coding sequence of the dopamine D₃ receptor gene. No statistical significant differences of allele frequencies or genotype frequencies could be found between the two groups. Neither were there any significant relationships between allele frequencies and a number of clinical variables within the schizophrenic subsample. However, if not corrected for multiple testing, an association was found between homozygosity and positive response to neuroleptic drugs. The present study does not provide evidence that the BalI polymorphism in the dopamine D₃ receptor gene is involved in the pathophysiology of schizophrenia. Further investigations with an increased number and variety of patients concerning response to neuroleptic drugs and expression of the receptor in human brain should be performed to definitively exclude this hypothesis.     

多巴胺D4受体基因与强迫症的关联

目的：探讨多巴胺D4受体DRD4基因多态性同强迫症（OCD）的关系。方法：采用PCR-AmFLP技术测定105例OCD患者和100例健康对照者的DRD4基因48bp可变数目重复序列的多态性。结果：OCD组与对照组间等位基因频数分布差异显著（P〈0.05）;其中患者组在4倍48bp重复序列纯合子的分布上明显低于对照组（P〈0.05）。结论：DRD4基因48bp可变数目重复序列的多态性可能与强迫症的发病有关。     

Association of mitochondrial complex I subunit gene NDUFV2 at 18p11 with bipolar disorder in Japanese and the National Institute of Mental Health pedigrees.

BACKGROUND: Linkage with 18p11 is one of the replicated findings in molecular genetics of bipolar disorder. Because mitochondrial dysfunction has been suggested in bipolar disorder, NDUFV2 at 18p11, encoding a subunit of the complex I, reduced nicotinamide adenine dinucleotide (NADH)ubiquinone oxidoreductase, is a candidate gene for this disorder. We previously reported that a polymorphism in the upstream region of NDUFV2, -602G> A, was associated with bipolar disorder in Japanese subjects; however, functional significance of -602G> A was not known. METHODS: We screened the further upstream region of NDUFV2. We performed a case-control study in Japanese patients with bipolar disorder and control subjects and a transmission disequilibrium test in 104 parent and proband trios of the National Institute of Mental Health (NIMH) Genetics Initiative pedigrees. We also performed the promoter assay to examine functional consequence of the -602G> A polymorphism. RESULTS: The -602G> A polymorphism was found to alter the promoter activity. We found that the other haplotype block surrounding -3542G> A was associated with bipolar disorder. The association of the haplotypes consisting of -602G> A and -3542G> A polymorphisms with bipolar disorder was seen both in Japanese case-control samples and NIMH trios. CONCLUSION: Together these findings indicate that the polymorphisms in the promoter region of NDUFV2 are a genetic risk factor for bipolar disorder by affecting promoter activity.     

Association of neural cell adhesion molecule 1 gene polymorphisms with bipolar affective disorder in Japanese individuals.

BACKGROUND: Although the pathogenesis of mood disorders remains unclear, heritable factors have been shown to be involved. Neural cell adhesion molecule 1 (NCAM1) is known to play important roles in cell migration, neurite growth, axonal guidance, and synaptic plasticity. Disturbance of these neurodevelopmental processes is proposed as one etiology for mood disorder. We therefore undertook genetic analysis of NCAM1 in mood disorders. METHODS: We determined the complete genomic organization of human NCAM1 gene by comparing complementary deoxyribonucleic acid and genomic sequences; mutation screening detected 11 polymorphisms. The genotypic, allelic, and haplotype distributions of these variants were analyzed in unrelated control individuals (n = 357) and patients with bipolar disorder (n = 151) and unipolar disorder (n = 78), all from central Japan. RESULTS: Three single nucleotide polymorphisms, IVS6+32T>C, IVS7+11G>C and IVS12+21C>A, displayed significant associations with bipolar disorder (for allelic associations, nominal p =.04, p =.02, and p =.004, respectively, all p >.05 after Bonferroni corrections). Furthermore, the haplotype located in a linkage disequilibrium block was strongly associated with bipolar disorder (the p value of the most significant three-marker haplotype is .005). CONCLUSIONS: Our results suggest that genetic variations in NCAM1 or nearby genes could confer risks associated with bipolar affective disorder in Japanese individuals.     

No association between dopamine D2 receptor gene (DRD2) and human intelligence

Summary. Significantly diminished intellectual functioning, as indicated by appropriately administered IQ tests with scores below 70, is a frequent mental handicap leading to severe social disadvantages and serves as a paradigm for molecular genetic research of complex disorders and traits due to its multitude of known and unknown, genetic as well as environmental causes. Since the number of confounding variables is expected to be considerably reduced in the normal population at the opposite ends of the IQ distribution, we employed a contrast of extremes approach by comparing adults of high (N = 71) and average IQ (N = 78) in association studies to search for genes involved in the multigenic forms of familial mental retardation. The dopamine D2 receptor gene (DRD2) was chosen as a candidate gene for general cognitive ability (g) since it has been found to be associated with visuospatial ability which in turn is highly correlated with g. Confirming two similar studies in children, however, no significant differences were obtained. Given three negative studies, the DRD2 gene is unlikely to pay a major role in g. Received March 13, 2000; accepted July 27, 2000     

Possible association between a haplotype of the GABA-A receptor alpha 1 subunit gene (GABRA1) and mood disorders.

BACKGROUND: The gamma-aminobutyric acid (GABA) neurotransmitter system has been implicated in the pathogenesis of mood disorders. The GABRA1 gene encodes one of the subunits of GABA-A receptor and is located on human chromosome 5q34-q35, which is a region reportedly linked to mood disorders. We examined the GABRA1 gene as a candidate for mood disorders. METHODS: We performed mutation screening of GABRA1 in 24 Japanese bipolar patients and evaluated associations in Japanese case-control subjects consisting of 125 patients with bipolar disorder, 147 patients with depressive disorders, and 191 healthy control subjects. Associations were confirmed in the National Institute of Mental Health (NIMH) Initiative Bipolar Pedigrees, which consists of 88 multiplex pedigrees with 480 informative persons. RESULTS: We identified 13 polymorphisms in the GABRA1 gene. Nonsynonymous mutations were not found. Association of a specific haplotype with affective disorders was suggested in the Japanese case-control population (corrected p=.0008). This haplotype association was confirmed in the NIMH pedigrees (p=.007). CONCLUSIONS: These results indicate that the GABRA1 gene may play a role in the etiology of bipolar disorders.     

多巴胺D5受体基因多态性与慢性抽动障碍的关联分析

目的研究慢性抽动障碍与多巴胺D5受体基因多态性是否相关联。方法采用聚合酶链式反应(PCR)、限制性片段长度多态性(RFLPs)与琼脂糖电泳技术的方法,对176个符合CCMD-3诊断标准的慢性抽动障碍儿童与其亲生父母的多巴胺D5受体基因多态性分型,采用病例对照研究,数据统计采用单体型相对风险(GHRR和HHRR)与传递不平衡检验(TDT)方法进行分析。结果慢性抽动障碍与多巴胺D5受体基因多态性无显著关联。GHRR值为0．32～1．61;HHRR值为1.82;TDT值为2．25,其P值均大于0．05。结论慢性抽动障碍与多巴胺D5受体基因多态性无关联。     

多巴胺转运体基因与注意缺损多动障碍

目的　探讨注意缺损多动障碍（ＡＤＨＤ） 与多巴胺转运体（ＤＡＴ１） 基因间的关系。方法　分别采用基于单体型和基于基因型的单体型相对风险分析方法,在上海地区汉族人群中对ＡＤＨＤ 与ＤＡＴ１ 基因微卫星多态性进行遗传关联分析。结果　①上海地区汉族人中,ＤＡＴ１ 基因多态以４８０ ｂｐ 重复片段为主,其基因频率为９２％ 。②以父母双亲为对照,经ＧＨＲＲ 和ＨＨＲＲ 分析,ＤＡＴ１ 基因与ＡＤＨＤ 均无关联。结论　上海地区汉族人群中ＤＡＴ１ 基因多态与ＡＤＨＤ 无关。     

多巴胺D_3受体基因多态性与精神分裂症临床表型

目的：探讨多巴胺D3受体（DRD3）基因多态性与精神分裂症临床表型的关系。方法：对73个精神分裂症核心家系83例精神分裂症患者（患者组）及其146名父母（父母组）应用聚合酶链反应、限制性内切酶消化方法、琼脂糖凝胶电泳结合紫外凝胶成像系统检测DRD3基因中的3个位点（Ser9Gly、Ala38Thr和-205A/G）的多态性;采用阳性与阴性症状量表（PANSS）评定精神分裂症临床表型。结果：两组DRD3基因中3个位点的基因型分布及等位基因的频率分布差异无显著性;但在患者组中,对Ser9Gly位点3种基因型（Ser9Ser、Ser9Gly和Gly9Gly）进行分组比较时,Gly9Gly组的PANSS抑郁因子评分明显高于Ser9Ser组和Ser9Gly组,3组间比较,差异有显著性（P=0.042）。对Ala38Thr位点3种基因型（Ala38Ala、Ala38Thr和Thr38Thr）进行分组比较,PANSS总分及各因子分在Ala38Ala、Ala38Thr和Thr38Thr组间差异均无显著性。对-205A/G位点3种基因型（A/A、A/G和G/G）进行分组比较,G/G组的PANSS反应缺乏因子评分明显高于A/A组和A/G组,3组间比较,差异有显著性（P=0.048）。结论：DRD3基因变异可能与精神分裂症的病理症状有关。     

Association between DRD4 gene and performance of children with ADHD in a test of sustained attention.

BACKGROUND: The adoption of neuropsychological tests as endophenotypic measures can provide an increased sensitivity to specific dimensions of attention-deficit/hyperactivity disorder (ADHD). METHODS: The association between a variable number of tandem repeats polymorphism at the dopamine D4 receptor gene (DRD4) and the performance of children and adolescents with ADHD in a continuous performance test (CPT) was evaluated. The sample comprised 90 clinically referred children and adolescents with ADHD. Errors of omission and commission in the CPT were computed and the number of 48-base pairs tandem repeats in the exon III of DRD4 was assessed. RESULTS: The presence of a 7-repeat allele was associated with more errors of commission and the homozygosity of the 4-repeat allele was related to fewer errors of commission and omission even after adjusting for age. CONCLUSIONS: These findings bring further evidence on the role of DRD4 polymorphisms on the performance in sustained attention tasks among children and adolescents with ADHD diagnosis.     

A transmission disequilibrium test of the Ser9/Gly dopamine D3 receptor gene polymorphism in adult attention-deficit hyperactivity disorder

Convincing data support the hypothesis that genetic factors are involved in the etiology of attention-deficit hyperactivity disorder (ADHD). Various lines of evidence have shown that the dopamine system plays a crucial role in the pathophysiology of ADHD. The dopamine D3 receptor gene (DRD3) represents a promising candidate to examine in ADHD. Animal studies have shown that DRD3 mRNA is highly expressed in the ventral striatum suggesting an involvement of this receptor in the control of motor behaviour. Manipulation of DRD3 in rodents has led to a mouse model with nonfunctional D3 receptors that displays hyperactive behaviour in various environmental conditions. Furthermore, administration of 7-OH-DPAT, a dopaminergic agonist that binds preferentially to D3 receptors exerts an inhibitory effect on locomotor activity while D3 antagonists induce hyperactivity. Among various polymorphisms described for DRD3, the BalI polymorphism is most interesting because it codes for an aminoacid substitution in the N-terminus of the receptor. The receptor products of the two alleles (Ser/Gly) exhibit differential affinity for dopamine. To determine if DRD3 Ser9/Gly is involved in the susceptibility to ADHD we genotyped 39 adults with ADHD and their respective parents (trios). Adult ADHD represents a promising phenotype for studying the genetic component of the disorder. In fact, a recent family study has shown that relatives of adult ADHD patients have a higher rate of ADHD compared to relatives of children with ADHD suggesting a stronger genetic component for the adult version. The results of genotyping in the 39 trios analyzed with the transmission disequilibrium test showed no excess of transmission for DRD3 MscI/BalI alleles (χ²=0.360; DF=1; P=0.54). This result, although from a relatively small sample, indicates that it is unlikely that DRD3 is playing a major role in the etiology of ADHD in our sample.     

Changes in striatal dopamine transporters in bipolar disorder and valproate treatment

BackgroundPrevious studies suggested that a disturbance of the dopamine system underlies the pathophysiology of bipolar disorder (BD). In addition, the therapeutic action of medications for treating BD, such as valproate (VPA), might modulate dopamine system activity, but it remains unclear. Here, we aimed to investigate the role of the striatal dopamine transporter (DAT) in BD patients and in social defeat (SD) mice treated with VPA.MethodsWe enrolled community-dwelling controls (N = 18) and BD patients (N = 23) who were treated with VPA in a euthymic stage. The striatal DAT availabilities were approached by TRODAT-1 single photon emission computed tomography. We also established a chronic SD mouse model and treated mice with 350 mg/kg VPA for 3 weeks. Behavioral tests were administered, and striatal DAT expression levels were determined.ResultsIn humans, the level of striatal DAT availability was significantly higher in euthymic BD patients (1.52 ± 0.17 and 1.37 ± 0.23, p = 0.015). Moreover, the level of striatal DAT availability was also negatively correlated with the VPA concentration in BD patients (r = −0.653, p = 0.003). In SD mice, the expression of striatal DAT significantly increased (p < 0.001), and the SD effect on DAT expression was rescued by VPA treatment.ConclusionsThe striatal DAT might play a role in the pathophysiology of BD and in the therapeutic mechanism of VPA. The homeostasis of DAT might represent a new therapeutic strategy for BD patients.     

Genome-wide scan and conditional analysis in bipolar disorder: evidence for genomic interaction in the National Institute of Mental Health genetics initiative bipolar pedigrees.

BACKGROUND: In 1989 the National Institute of Mental Health began a collaborative effort to identify genes for bipolar disorder. The first 97 pedigrees showed evidence of linkage to chromosomes 1, 6, 7, 10, 16, and 22 (Nurnberger et al 1997). An additional 56 bipolar families have been genotyped, and the combined sample of 153 pedigrees studied. METHODS: Three hierarchical affection status models were analyzed with 513 simple sequence repeat markers; 298 were common across all pedigrees. The primary analysis was a nonparametric genome-wide scan. We performed conditional analyses based on epistasis or heterogeneity for five regions. RESULTS: One region, on 16p13, was significant at the genome-wide p <.05 level. Four additional chromosomal regions (20p12, 11p15, 6q24, and 10p12) showed nominally significant linkage findings (p 相似文献   

Increased affinity of dopamine for D(2) -like versus D(1) -like receptors. Relevance for volume transmission in interpreting PET findings

Evidence indicates that dopamine (DA) mainly acts as a volume transmission (VT) transmitter through its release into the extracellular fluid where the D(1) -like and D(2) -like receptors are predominantly extrasynaptic. It was therefore of interest to compare the affinities of the two major families of DA receptors. [(3)H] raclopride /DA and [(3)H] SCH23390/DA competition assays compared the affinity of DA at D(2) -like and D(1) -like receptors in rat dorsal striatal membrane preparations as well as in membrane preparations from CHO cell lines stably transfected with human D(2L) and D(1) receptors. The IC(50) values of DA at D(2) -like receptors in dorsal striatal membranes and CHO cell membranes were markedly and significantly reduced compared with the IC(50) values of DA at D(1) -like receptors. These IC(50) values reflect differences in both the high and low affinity states. The K(iH) value for DA at [(3)H] raclopride-labeled D(2) -like receptors in dorsal striatum was 12 nM, and this can help explain PET findings that amphetamine-induced increases in DA release can produce an up to 50% decrease of [(11)C] raclopride binding in the dorsal striatum in vivo. These combined results give indications for the existence of striatal D(2) -like receptor-mediated DA VT at the local circuit level in vivo. The demonstration of a K(iH) value of 183 nM for DA at D(1) antagonist-labeled D(1) -like receptors instead gives a likely explanation for the failure of a reduction of D(1) -like receptor binding after amphetamine-induced DA release in PET studies using the D(1) -like antagonist radioligands [(11)C] SCH23390 and [(11)C] NNC. It seems difficult to evaluate the role of the extrasynaptic D(1) receptors in VT in vivo with the PET radioligands available for this receptor.     

There is no association between the serotonin receptor gene and bipolar I disorder in the Korean population

Abstract

Objective: Despite the close relationship between the functional polymorphism C(-1019)G (rs6295) of the serotonergic 1A receptor (5-HT1A) and mood, few studies have investigated the relationship between rs6295 and bipolar disorder. Aims: In this study, we aimed to investigate whether rs6295 is associated with clinical prognosis and treatment response in patients with bipolar I disorder acute manic episodes. Methods: One hundred twenty-eight patients with bipolar I disorder and one hundred sixty-eight healthy controls were recruited. Associations between patients with bipolar I disorder and healthy controls were compared. In addition, age at onset, number of admissions, and treatment response, including response rate, mean changes in manic symptoms, number of anti-manic agents and the total dosage of mood stabilizers for acute manic symptoms were compared between the rs6295 GG and CG+ CC groups in patients with bipolar I disorder. We conducted a separate subgroup analysis according to gender. Results: There were no differences in frequency between patients and controls. In patients with bipolar disorder, clinical prognosis and treatment response were no different between GG and CG+ CC groups. However, in a subgroup analysis according to gender, male, but not female, patients in the GG group had a longer duration of illness and a greater number of both previous episodes and psychiatric ward admissions than did the GC+ CC group. Conclusions: Further studies should investigate the relationship between 5-HT1A polymorphisms and bipolar disorder in terms of mood episode and gender.     

Genetic structure of the dopamine receptor D4 gene (DRD4) and lack of association with schizophrenia in Japanese patients

In order to investigate the contribution of genetic variation in the human dopamine receptor D4 gene (DRD4) to the risk of developing schizophrenia, we carried out a genetic analysis of 27 polymorphisms in 216 schizophrenic patients and 243 healthy controls from the Kyushu region of Japan. Twenty-two single nucleotide polymorphisms (SNPs) and five insertion/deletion polymorphisms were analyzed in this study, including four novel SNPs and a novel mononucleotide repeat. Linkage disequilibrium (LD) and haplotype analyses reveal weak LD across the DRD4 gene. In univariate analysis female individuals with allele -521C had a higher risk for schizophrenia. However, this finding was not significant after correction for multiple hypothesis testing. No other polymorphisms or haplotypes differed between schizophrenic patients and controls. Likewise, multivariate analyses did not reveal any statistically significant associations.