多巴胺D2受体基因与迟发性运动障碍关联研究

目的探讨DRD2基因TaqI多态性的分布与迟发性运动障碍(TD)的关联性.方法应用聚合酶链反应-限制性片段长度多态的方法,检测100例精神分裂症伴TD患者、60例无TD患者和102名正常人DRD2基因TaqI多态性,比较各组等位基因和基因型频率分布的差异.结果经吻合度检验,精神分裂症伴有TD组、无TD组和正常对照组DRD2基因各基因型的分布均符合Hardy-Weinberg平衡法则(x2=0.242,0.208,0.002,υ均=1,P均＞0.05);经比较,显示各基因型及等位基因在各组间分布无显著性差异(经Z检验,υ均=1,P均＞0.05);TD患者DRD2基因多态分布在不同性别之间无显著性差异(P＞0.05);在TD组中,基因型频数及等位基因频数与病程、服药时间、药物、剂量和AIM评分无显著性意义(P＞0.05).结论DRD2基因TaqI多态性可能与TD的发生无关联性.     

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。     

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.     

Brain uptake and distribution of the dopamine D3/D2 receptor partial agonist [11C]cariprazine: An in vivo positron emission tomography study in nonhuman primates

Cariprazine is a dopamine D₃/D₂ receptor partial agonist antipsychotic candidate, which binds with high affinity to dopamine D₃ and D₂ receptors (with ～10‐fold higher in vitro affinity to D₃ vs. D₂ receptors) and with moderate affinity to 5‐HT_1A receptors. The main objective of the present molecular imaging investigation was to evaluate the uptake and reversible binding of 11‐C labeled cariprazine in the nonhuman primate brain, in relation to the known distributions of dopamine D₂ and D₃ receptors. We examined the brains of two cynomolgus monkeys at baseline condition as well as during a pharmacological blocking condition, using unlabeled cariprazine or raclopride as blockers before injection of [¹¹C]cariprazine. Of the total injected radioactivity, ～7% entered the brain and ～3–4% remained in the brain after 90 min, indicating good blood brain barrier penetration and slow washout. It was possible to block cariprazine binding with unlabeled cariprazine and raclopride indicating that [¹¹C]cariprazine binds to dopamine D₃/D₂ receptors. Nondisplaceable binding potential (BP_ND) measurements, using a simplified reference tissue model and cerebellum as the reference region, yielded values of ～1.5 and 0.3 in the striatum and thalamus, respectively. Striatum BP_ND values were reduced by 80 and 85% following pretreatment with 0.1 mg/kg IV injection of unlabeled cariprazine and 1 mg/kg IV injection of unlabeled raclopride, respectively. The data confirm that cariprazine, a novel antipsychotic drug candidate, enters the nonhuman primate brain readily and binds to dopamine D₃/D₂ receptors. Furthermore, in PET imaging [¹¹C]cariprazine can effectively visualize dopamine D₃/D₂ receptors in the nonhuman primate brain. Synapse 67:258–264, 2013. © 2013 Wiley Periodicals, Inc.     

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 [(χ² (2) = 12.35, corrected p = 0.012]. The − 141C Del allele was more common in patients than in controls [0.19 vs. 0.13; χ² (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.     

多巴胺D3受体基因多态性与精神分裂症亚型及利培酮疗效相关性分析

目的探讨多巴胺D3受体(dopamine D3 receptor,DRD3)基因第一外显子丝氨酸9甘氨酸(Ser9Gly)多态性与精神分裂症临床亚型、药物疗效的关联.方法 241 例汉族首发精神分裂症患者,采用限制性片段长度多态性(restriction fragment length polymorphism,RFLP)技术测定基因型.分析判断基因多态性与精神分裂症的临床亚型、药物疗效的关联. 结果精神分裂症各亚型Ser9Gly等位基因分布存在显著性差异(p <0.05).利培酮疗效不同的患者间Ser9Gly等位基因多态性均无显著性差异. 结论 DRD3受体基因第一外显子Ser9Gly多态性可能与精神分裂症亚型相关,而与患者对药物的反应不相关.     

The association between the Lie scale of the Maudsley personality inventory and striatal dopamine D2/D3 receptor availability of healthy Chinese community subjects.

The present study examined the relationship between the Lie scale scores and striatal D(2)/D(3) receptor availability with respect to the cerebellum in 42 healthy community volunteers in Taiwan using single photon emission computed tomography (SPECT) with [(123)I]iodo-benzoaminde (IBZM). Even after controlling of age and educational level, subjects' Lie scale scores of the Maudsley personality inventory correlate negatively with D(2)/D(3) receptor availability. Individual with higher Lie scale scores may have higher impulsivity due to lower dopaminergic availability.     

强啡肽原基因和多巴胺D2受体基因与精神分裂症的关系研究

目的探讨甘肃省汉族人群强啡肽原（Prodynorphin,PDYN）基因和多巴胺D2受体（dopamine D2 receptor,DRD2）基因与精神分裂症遗传易感性的关系及其相互作用对精神分裂症的影响。方法采用聚合酶链反应-限制性片段长度多态性〈PCR—RFLP）技术检测128例精神分裂症患者和124例健康对照者PDYN基因启动子区68bp可变串联重复序列（variable number tandem repeat,VNTR）多态性及DRD2基因启动子区-141位胞嘧啶插入／缺失（-141C Ins／Del）多态性的基因型和等位基因的频率。结果精神分裂症患者PDYN等位基因和基因型频率与健康对照者没有显著不同;精神分裂症患者DRD2-141C Del等位基因的频率则显著低于健康对照者;在携带DRD2-141C Del等位基因的精神分裂症患者和健康对照者中,精神分裂症患者PDYN等位基因3的频率显著高于健康对照者。结论DRD2-141C Del等位基因的降低可能与精神分裂症的遗传易感性相关,单独的PDYN基因多态性不会改变精神分裂症的危险度,但是通过与DRD2—141C Del等位基因的上位相互作用可能与这种疾病的易感性相关。     

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。     

多巴胺D3受体基因多态性与精神分裂症患者迟发性运动障碍的关联分析

目的　观察广州地区汉族伴或不伴迟发性运动障碍 (TD)的精神分裂症患者多巴胺D3受体 (DRD3)基因Ser 9 Gly多态性分布 ,探讨DRD3基因Ser 9 Gly多态性与TD发生的关系。方法对 1 4 0例精神分裂症患者采用不自主运动评定量表 (AIMS)进行评定 ,其中 53例伴TD ,87例不伴TD。应用聚合酶链反应和限制性内切酶长度多态性方法 ,检测 1 4 0例患者的DRD3基因Ser 9 Gly多态性 ,并对DRD3各等位基因及基因型与精神分裂症患者的TD表型进行关联分析。结果　 (1 )TD组与无TD组患者基因型总体分布的差异无显著性 (χ2 =5 6 ,υ =2 ,P >0 0 5) ,等位基因频数分布的差异有显著性 (χ2 =5 1 1 ,υ =1 ,P <0 0 5)。 (2 )按性别分组后 ,在男性患者中 ,伴TD患者较不伴TD患者 1 / 1基因型和等位基因 1频率的差异有显著性 (χ2 =5 2 4 ,χ2 =5 0 6 ,P <0 0 5) ,等位基因 2的差异有显著性 (χ2 =5 0 6 ,P <0 0 5)。在女性患者中 ,DRD3各基因型及等位基因的频率的差异均无显著性 (P >0 0 5)。结论　DRD3基因Ser 9 Gly多态性可能与精神分裂症尤其是男性患者的TD关联     

Striatal dopamine D2 receptor availability predicts the thalamic and medial prefrontal responses to reward in cocaine abusers three years later

Low levels of dopamine (DA) D2 receptor availability at a resting baseline have been previously reported in drug addicted individuals and have been associated with reduced ventral and dorsal prefrontal metabolism. The reduction in DA D2 receptor availability along with the reduced ventral frontal metabolism is thought to underlie compromised sensitivity to nondrug reward, a core characteristic of drug addiction. We therefore hypothesized that variability in DA D2 receptor availability at baseline will covary with dynamic responses to monetary reward in addicted individuals. Striatal DA D2 receptor availability was measured with [¹¹C]raclopride and positron emission tomography and response to monetary reward was measured (an average of three years later) with functional magnetic resonance imaging in seven cocaine‐addicted individuals. Results show that low DA D2 receptor availability in the dorsal striatum was associated with decreased thalamic response to monetary reward; while low availability in ventral striatum was associated with increased medial prefrontal (Brodmann Area 6/8/32) response to monetary reward. These preliminary results, that need to be replicated in larger sample sizes and validated with healthy controls, suggest that resting striatal DA D2 receptor availability predicts variability in functional responses to a nondrug reinforcer (money) in prefrontal cortex, implicated in behavioral monitoring, and in thalamus, implicated in conditioned responses and expectation, in cocaine‐addicted individuals. Synapse 64:397–402, 2010. © 2009 Wiley‐Liss, Inc.     

Activity, non-selective attention and emotionality in dopamine D2/D3 receptor knock-out mice

In order to assess the role of dopamine (DA) D2 and D3 receptors in the modulation of behaviour, we analysed exploration in a spatial novelty in mouse model systems. Genetically engineered mice mutants have been used that carry normal, partial or no expression of D2R, D3R, or both D2R/D3R (double mutants) DA receptor subtypes. Adult male mice were exposed for 30 min to a Làte-maze. The behaviour was analysed for indices of activity, orienting (rearing frequency), scanning times (rearing duration) and defecation score (emotionality). D2R −/− and +/− as well as the D2R/D3R double homozygous mutants were less active than wild-type (WT) controls in travelled distance. In contrast D3R +/− were more active than WT mice in the first part of the test. As to orienting frequency, the D2R −/− were less active than WT during the entire test-period, whereas the D2 +/− mutants were less active than WT only in the second part of the test. Moreover, the D3R −/− and +/− mutants showed less and more rearing frequency than WT, respectively, during the entire test. Finally, the D2/D3R −/− double mutants were also less active than WT during the entire test period. As to scanning times, D2R +/− and −/− mutants were higher than WT during the entire test or only in the second part, respectively. The D3R +/− and −/− were not different from WT, whereas the D2/D3R −/− double mutants showed shorter scanning times only in the first part of the test. As to emotionality index, the defecation score, was lower only in D3R +/− mutants. Thus, the dopamine D2 and D3 receptor subtypes appear to be differentially involved in the modulation of activity, orienting and scanning phases of attention. Lastly double mutation experiments reveal an interaction between D2R and D3R with the former prevailing on the latter.     

Striatal dopamine D2/D3 receptor availability correlates with individual response characteristics to pain

We studied in healthy humans the contribution of cerebral dopamine D2/D3 receptors to individual differences in response characteristics to painful stimulation. Positron emission tomography was used to measure the dopamine D2/D3 binding potential (D2/D3 BP) with [(11)C]raclopride in the striatum (n = 8) and with [(11)C]FLB 457 in the extrastriatal regions (n = 11). Sensitivity to cutaneous heat pain was assessed by a traditional threshold method and by an analysis based on the signal detection theory which allows the separation of an individual subject's discriminative capacity from the response criterion, i.e. the area under the receiver operating characteristic curve provides a measure of the sensory discriminability (sensory factor) and the response criterion gives an estimate of the subject's response bias or attitude (nonsensory factor). The pain threshold and response criterion were inversely correlated with the D2/D3 BP in the right putamen, whereas the discriminative capacity was not significantly correlated with the D2/D3 BP in any brain region. The correlation of the D2/D3 BP in the putamen with the pain threshold and the subject's response criterion may rather be explained by a dopaminergic effect on nonsensory factors determining the subject's attitude towards pain than by a dopaminergic effect on the subject's discriminative capacity. Alternatively, striatal dopamine D2/D3 receptors could control a modulatory pathway producing a parallel shift in the stimulus-response function for sensory signals, mimicking a change in the subject's response criterion.     

Age-related changes of dopamine D1-like and D2-like receptor binding in the F344/N rat striatum revealed by positron emission tomography and in vitro receptor autoradiography

To clarify age-related changes in dopamine D1-like and D2-like receptor binding in the striatum, positron emission tomography (PET) and in vitro receptor autoradiography (in vitro ARG) were performed using F344/N rats of various ages (6, 12, 18, and 24 months). In the PET study, [11C]SCH23390 and [11C]raclopride were used to image dopamine D1-like receptors and dopamine D2-like receptors, respectively, while [3H]SCH23390 and [3H]raclopride were used for the in vitro ARG study. With PET, we calculated the binding potential (= k3/k4, Bmax/Kd) of [11C]SCH23390 and [11C]raclopride in the striatum according to the curve fitting (CF) and the Logan plot (LP) methods. The binding potential of [11C]SCH23390 in the striatum demonstrated significant decrease as a function of age (max. decrease -26%) by the LP method, while this was not observed in the data analyzed by the CF method. In contrast, the binding potential of [11C]raclopride in the striatum decreased significantly with age by both the CF (max. decrease -28%) and the LP (max. decrease -36%) methods. However, no significant difference by either method was observed in rats between 6 and 12 months old using either ligand. In the in vitro ARG study, the specific binding (fmol/mg tissue) of [3H]SCH23390 and [3H]raclopride in the striatum were determined. Both [3H]SCH23390 and [3H]raclopride binding declined considerably with age as noted by comparing 12, 18, and 24-month-old rats against those 6 months old (max. decrease -29% and -31%, respectively). The substantial difference in binding shown in 12-month-olds in comparison with 6-month-olds using either ligand with in vitro ARG was in contrast with the PET results. These distinctions between the PET and the in vitro ARG studies may be attributed to the receptor microenvironment created under these experimental conditions. The results indicate that PET with LP analysis is useful in obtaining age-related changes of D1-like and D2-like receptor binding in the striatum of living rats.     

Dopamine D2 receptor binding in drug-naïve patients with schizophrenia examined with raclopride-C11 and positron emission tomography

The aim was to test the dopamine hypothesis of schizophrenia in a further analysis of D₂-like dopamine binding using the radioligand [¹¹C]raclopride and high resolution 3-dimensional (3D) PET. Eighteen drug-naive patients with schizophrenia and seventeen control subjects were examined. The D₂ binding potential (BP) in the putamen, the caudate and the thalamus was calculated using the simplified reference tissue model. The volume of regions of interest was controlled for by MRI. Symptoms were rated with the Positive and Negative Syndrome Scale for Schizophrenia (PANSS). No significant group differences were found for D₂ BP in the putamen or in the caudate and there was no significant hemispheric difference for any region. In the right thalamus the D₂ BP was significantly lower in patients as compared to control subjects, whereas a numerical difference did not reach statistical significance for the left thalamus. There was no significant correlation between D₂ BP and total PANSS score in any region. There was a highly significant age effect in the caudate and in the putamen, but not in the thalamus. In this relatively large PET study of exclusively drug-naive schizophrenic patients, a lower D₂ BP in the right thalamus was found in the patient group. This finding is in agreement with two previous studies in Sweden and in Japan using the high-affinity radioligand [¹¹C]FLB 457 and provide further support for a role of dopamine in the thalamus related to the pathophysiology of schizophrenia.     

Striatal binding of11C-NMSP studied with positron emission tomography in patients with persistent tardive dyskinesia: no evidence for altered dopamine D2 receptor binding

Summary Dopamine D₂ receptor binding characteristics were studied by positron emission tomography (PET) using N-¹¹C-methyl spiperone as receptor ligand in patients on longterm treatment with neuroleptic drugs and in control subjects. Eight of the patients had symptoms of tardive dyskinesia whereas three patients did not have any symptoms. Control subjects comprised 5 healthy volunteers and 7 patients with pituitary tumors. All patients had been free of neuroleptic drugs for at least 4 weeks. The time dependent regional radioactivity in the striatum was measured and the receptor binding rate, k₃, proportional to receptor number, B_max and association rate for the receptor was calculated in relation to the cerebellum. The lack in difference in k₃ values between TD patients, neuroleptic treated patients without TD and control subjects throws doubt on the hypothesis that changes in striatal D₂ dopamin receptor number or binding affinity is an etiological mechanism for persistent TD.     

Use of positron emission tomography to measure the effects of nalmefene on D1 and D2 dopamine receptors in rat brain

Positron emission tomography (PET) has been used in humans and in non-human primates to image and measure radioligand binding to neuroreceptors. The present study evaluated the feasibility of performing high-resolution PET experiments in a rodent model to measure receptor kinetics. The effects of acute and chronic administration of the opioid antagonist, nalmefene, on the binding activity of [¹¹C]SCH23390 and [¹¹C]N-methylspiperone at D₁ and D₂ dopamine receptors, respectively, was investigated in the rat. The interaction between central opioid and dopaminergic systems has been the focus of much attention due to their interactive role in mediating reinforcement and locomotor activity. In the present study, adult male Sprague–Dawley rats received either a single injection of 10 mg/kg of nalmefene or control vehicle solution 1 h prior to the PET scan or were chronically administered 10 mg/kg/day of nalmefene or vehicle for 7 days by an osmotic minipump. Following acute administration of nalmefene, the binding potential of [¹¹C]SCH23390 in the striatum was significantly increased. No changes in [¹¹C]N-methylspiperone binding were found. Following chronic nalmefene administration, no significant change in either [¹¹C]SCH23390 binding potential or [¹¹C]N-methylspiperone binding was detected. These results suggest that nalmefene administration produces transient changes in the binding potential of D₁-receptors in the striatum that are normalized after 1 week of steady-state administration.     

An association study between the Cys311 variant of dopamine D2 receptor gene and schizophrenia in the Okinawan population

Abstract  Neuroleptic drugs have a high affinity for the dopamine D₂ receptor (DRD2); therefore DRD2 is thought to be a candidate gene for schizophrenia. Arinami et al . have reported a positive association between schizophrenia and the Cys311 variant of the DRD2 gene. We determined the allele frequency of this polymorphism in 78 Okinawan schizophrenic patients and 112 control subjects. The patients and controls did not differ significantly in allele frequencies of Cys311.     

精神分裂症与多巴胺D4受体基因及载脂蛋白E基因的关联分析

目的　探讨上海地区汉族人群载脂蛋白E(apoE)基因、多巴胺D4 受体 (DRD4)基因与精神分裂症的易患性、患者的性别、发病年龄以及病程之间的关系。方法　应用聚合酶链反应扩增技术及限制性片段长度多态性对 80例精神分裂症患者和 80名正常人分别测定apoE、D4基因型和等位基因。结果　 (1 )患者组apoE等位基因ε2 频率明显高于对照组 ,与精神分裂症呈显著正关联 [相对危险度 (RR) =2 0 1 ,P <0 0 5] ;而且患者组男性等位基因ε2 频率明显高于对照组男性 ,与精神分裂症呈显著正关联 (RR =8 5l,P <0 0 5)。 (2 )DRD4基因与精神分裂症无关联 ,但是发病年龄与A2 ,A4等位基因及性别与 4/ 4基因型有关联 (P <0 0 5) ;(3)患者组与对照组携带ε4 与非携带ε4 间比较 ,DRD4基因的基因型和等位基因频率均无差异。患者组和对照组的组内携带ε4 与非携带ε4 间比较的差异均有显著性 ,对照组携带ε4 组的DRD4基因型 4/ 4 (85 % )和等位基因A4(89% )频率均明显高于非携带ε4组 (55 % ,67% ) ,而非携带ε4 组的等位基因A2 (2 9% )频率高于携带ε4 组 (1 2 % ) ;患者组非携带ε4 组的DRD4基因型 2 / 2 (1 3 % )和等位基因A2 (2 4 % )频率均高于携带ε4 组 (0 % ,8% )。结论　 (1 )apoE基因可影响精神分裂症患者的易患性     

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.