多巴胺D4受体基因与注意缺损多动障碍

为探讨注意缺损多动障碍(ADHD)与多巴胺D4受体基因(dopamineD4receptorgene,DRD4)间的关系,采用Amp-FLP的方法检测了上海地区汉族人群中68例ADHD患者及其父母DRD4的多态性,数据采用基于单体型的单体型相对风险(HHRR)及传递不平衡检验(TDT)进行遗传关联分析.结果表明HHRR分析和复等位基因的TDT检验,均未显示出与ADHD的遗传关联性(P＞0.05).提示上海地区人群中DRD4基因与ADHD无显著性关联。 Abstract:The present study was designed to investigate the association between attention-deficit hyperactivity disorder (ADHD) and the dopamine D4 receptor gene (DRD4).Amp-FLP was used to test the polymorphisms of DRD4 in 68 ADHD children and their parents from Shanghai.The haplotype-based haplotype relative risk (HHRR) and transmission disequilibrium test (TDT) methods were used to analyze the association between DRD4 and ADHD.In our samples we found no significant association between DRD4 and ADHD (P>0.05).Our results do not support that ADHD is associated with DRD4 in population in Shanghai.     

混合家系中NOTCH4基因多态与精神分裂症、心境障碍关联研究

文章旨在探讨NOTCH4基因多态性与精神分裂症（SP）、心境障碍（MD）的关系,搜寻中国汉族人群SP与MD的共同易患基因。在中国汉族人群中收集61个SP与MD的混合家系,应用PCR-RFLP方法对NOTCH4基因多态性-1725T/G、-25T/C分型,进行传递不平衡检验（TDT）和基于单体型的单体型相对风险分析（HHRR）。结果显示-1725T/G 与SP或MD无明显关联（P>0.05）;-25T/C与SP无明显关联（P>0.05）,与女性或发病年龄≤25岁的MD相关联（P<0.05）;单体型-1725G/-25T与SP相关联（P<0.05）,与MD无明显关联（P>0.05）。本研究结果提示,在我们研究的家系中NOTCH4或邻近基因可能是精神分裂症与心境障碍的共同易患基因之一。     

注意缺损多动障碍和儿茶酚-O-甲基转移酶基因无关联性

以往研究表明,儿茶酚胺系统可能参于注意缺损多动障碍（attention—deficit hyperactivityity disorder,ADHD）的发生,而儿茶酚胺-O-甲基转移酶（catechel—O—methyltransferase,COMT）是一种降解多巴胺和去甲肾上腺素系统的儿茶酚胺神经递质的酶。因此,采用两种以家系为基础的分析方法,即传递不平衡实验（transmission disequilibrium test,TDT）和单倍型为基础的单倍型相对风险率（haplotype—based haplotype relative risk,HHRR）去探讨COMT和中国人群中79个ADHD核心家系的关联性,ADHD诊断符合DSM—IV的诊断标准。TDT（X^2=1．03,df=1,P〉0．05）和HHRR（X^2=1．08,df=1,P〉0．05）两种方法的分析结果表明,COMT等位基因不能优先传递给ADHD儿童,提示在中国人群中ADHD与COMT基因无关联性。     

注意缺损多动障碍的X染色体基因组扫描分析

摘 要：注意缺损多动障碍（ADHD）是儿童期多见行为障碍。男孩发病多于女孩。家系、双生儿和寄养子研究显示该障碍发生具有遗传基础。但是病因尚不清楚。分子遗传学和药理学研究表明ADHD涉及到多巴胺和去甲肾上腺素等神经递质系统,一系列报告发现ADHD与多巴胺D4受体（DRD4）、多巴胺转运体（DAT1）和儿茶酚-O-甲基转移酶（COMT）等基因相关联。我们以往研究表明ADHD与X染色体上DXS7位点和MAOA基因相关联,而DXS7是紧密连锁于MAO基因。依此假设,我们应用基因组扫描技术探讨ADHD在X染色体上易感位点。采用TDT方法分析X染色体上48个DNA标志的多态性与中国人群中84个ADHD核心家系间的连锁关系,ADHD诊断依据DSM-III-R标准。TDT分析结果观察到如下位点与ADHD相连锁,DXS1214(TDT:χ2=18.1,df=7, P<0.01), DXS8102(TDT: χ2=7.9, df=3, P<0.05),DXS1068(TDT: χ2=21.9, df=9, P<0.01), DXS8015(TDT:χ2=14.6, df=7, P<0.05),DXS1059(TDT: χ2=27.8, df=10, P<0.01) 和DXS8088(TDT:χ2=20.4, df=3, P<0.01).研究资料提示X染色体上Xp11.4-Xp21和Xq23区域可能存在ADHD的易感基因。     

注意缺损多动障碍关联于DXS7位点 Association of Attention-Deficit Hyperactivity Disorder and the DXS7 Locus

采用单体型相对风险和传递/不平衡检验方法,在中国人群中对注意缺损多动障碍（ADHD）与DXS7位点进行了遗传关联分析。结果表明,以父母双亲为对照,DXS7位点157bp等位基因与ADHD具有显著关联(χ2=9.10, P<0.05)并连锁(χ2=9.53, P<0.05)。提示,ADHD关联和连锁于DXS7位点。 Abstract　The present study was designed to assess the genetic association between attention-deficit hyperactivity disorder(ADHD) and DXD7 locus polymorphism in Chinese population, with haplotype-based haplotype relative risk(HHRR) and the transmission/disequilibrium test(TDT) analysis. We found significant association(χ2=9.10, P<0.05) and linkage (χ2=9.53, P<0.05) between the 157bp DXS7 allele and DSM-Ⅲ-R-diagnosed ADHD(N=54) in trios composed of father, mother and affected offspring. Our results suggest that ADHD was associated and in linkage with DXS7 locus.     

在中国汉族人群中,以家系传递分析肿瘤坏死因子a-308A/G单核苷酸多态性与抽动秽语综合征

目的：探讨在中国汉族人群中,肿瘤坏死因子a（TNF-alpha,TNF-a）基因启动子区-308A/G单核苷酸多态性与抽动秽语综合征（Tourette syndrome,TS）的遗传易感性。方法：91例TS患者及其父母组成的核心家系成员经聚合酶链式反应-限制性片段长度多态性（polymerase chain reaction-restriction fragment lengthpolymor phism,PCR-RFLP）方法进行基因分型,评估所有研究对象的TNF-a-308A/G位点的等位基因频率和基因型频率的分布,进行传递不平衡检验（transmission disequilibrium test,TDT）,单体型相对风险（haplotype-based haplotyp erelativerisk,HHRR）,单体型风险（haplotype relative riskHRR）的研究。结果：TS患者及其父母的等位基因分布经Hardy-Weinberg（H-W）平衡检验显示符合遗传平衡法则。（x2〈3.84;P〉0.05）TDT、HHRR和HRR研究结果显示该多态性位点的等位基因频率和基因型频率均不存在传递不平衡。结论：我们的数据表明肿瘤坏死因子a启动子区-308A/G单核苷酸多态性位点不是中国汉族人群TS的易感基因位点。     

DRD4基因与人类认知能力的相关性研究

以某高校随机抽取的790余名汉族健康大学新生作为随机人群样本,采用PCR-SSCP结合DNA测序的方法探究位于多巴胺神经递质通路中的多巴胺D4受体基因(DRD4)上的共2个SNP,探索DRD4基因的正常功能多态与人认知能力的相关性。分析结果显示,DRD4基因上选取的两个SNP中,仅有rs936461与男性中央执行功能关联p值校正后仍然存在显著性(p=0.034)。说明DRD4基因可能与人的中央执行功能有关。     

在中国汉族人群中，以家系传递分析肿瘤坏死因子a-308A/G单核苷酸多 态性与抽动秽语综合征

目的:探讨在中国汉族人群中,肿瘤坏死因子a(TNF-alpha,TNF-a)基因启动子区-308A/G单核苷酸多态性与抽动秽语综合征(Tourette syndrome,TS)的遗传易感性。方法:91例TS患者及其父母组成的核心家系成员经聚合酶链式反应-限制性片段长度多态性(polymerase chain reaction-restriction fragment lengthpolymor phism,PCR-RFLP)方法进行基因分型,评估所有研究对象的TNF-a-308A/G位点的等位基因频率和基因型频率的分布,进行传递不平衡检验(transmission disequilibrium test,TDT),单体型相对风险(haplotype-based haplotyp erelativerisk,HHRR),单体型风险(haplotype relative riskHRR)的研究。结果:TS患者及其父母的等位基因分布经Hardy-Weinberg(H-W)平衡检验显示符合遗传平衡法则。(x2<3.84;P>0.05)TDT、HHRR和HRR研究结果显示该多态性位点的等位基因频率和基因型频率均不存在传递不平衡。结论:我们的数据表明肿瘤坏死因子a启动子区-308A/G单核苷酸多态性位点不是中国汉族人群TS的易感基因位点。     

多巴胺D1受体基因多态性与注意缺陷多动障碍的相关性研究

目的:探讨多巴胺D1受体(Dopamine D1 receptor, DRD1)基因启动子区G-48A、外显子区T1403C两个SNP位点与注意缺陷多动障碍(attention deficit hyperactivity disorder,ADHD)的关联性.方法:选取87名ADHD患者和103名正常对照,提取基因组DNA,采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术检测G-48A和T1403C两个多态性位点的基因型,SPSS13.0软件分析各位点的等位基因及基因型频率.结果:DRD1的G-48A基因型及等位基因频率分布在ADHD和对照组之间有统计学差异(p<0.05),ADHD组中等位基因A频率显著高于正常组(p<0.05).T1403C位点基因型及等位基因频率在ADHD组与健康对照组无统计学差异.结论:DRD1基因G-48A多态性可能与ADHD的发病有关,携带有等位基因A的个体可能更容易患ADHD.T1403C多态性与ADHD的发病无明显相关性.     

中国人MTHFR基因多态性与神经管畸形遗传易感性

目的：应用分子生物学方法进行遗传流行病学研究, 探讨MTHFR基因多态性在神经管畸形的遗传易感性中的作用。方法：应用PCR?RFLP方法检测MTHFR热敏感性基因型;对18个NTD核心家庭进行以父母为对照的病例对照研究,计算TDT和HHRR;另外对31例NTD胎儿和62例正常成年人进行的成组病例对照研究,计算MTHFR纯合突变对NTD的比值比。结果：核心家庭分析结果：比值比OR=3.2,95％CI=1.120～11.169;TDT（χ2）=5.762,P<0.05,HHRR（成组χ2）=6.727,P<0.05;胎儿MTHFR纯合突变对NTD的相对危险度OR=3?21,P<0?05。结论：研究结果说明,突变等位基因在神经管畸形核心家庭中存在突变基因(T)的遗传失衡现象,胎儿MTHFR基因第677位核苷酸的多态性是中国人NTD遗传易感性因素之一。 Abstract：The objective of the study is to clarify the effect of MTHFR thermolabile polymorphism on genetic susceptibility of NTD in Chinese population.MTHFR genotypes were detected using PCR-RFLP analysis; 18 NTD nuclear families were analysed as case-parental control study,from which Transmitted Disequillibrium Test(TDT) and Haplotype-based Haplotype Relative Risk (HHRR) were calculated; 31 NTD fetuses and 62 adult controls were analysed for calculation of OR of homozygotic MTHFR.The results are as follow:Nuclear family analysis: OR=3.2( 95％CI=1.120～11.169);TDT（paired χ2）=5.762,P<0.05,HHRR（χ2）=6.727,P<0.05;homozygotic MTHFR of fetus vs adult control: OR=3.21,P<0.05. The 677th allele of MTHFR is abnormally transmitted in NTD nuclear families.Homozygotic MTHFR of the fetus may be a genetic factor of NTD in China.     

Association of polymorphisms in the dopamine D4 receptor gene and the activity-impulsivity endophenotype in dogs

A variable number of tandem repeats (VNTR) polymorphism in exon 3 of the human dopamine D4 receptor gene ( DRD4 ) has been associated with attention deficit hyperactivity disorder (ADHD). Rodents possess no analogous repeat sequence, whereas a similar tandem repeat polymorphism of the DRD4 gene was identified in dogs, horses and chimpanzees. Here, we present a genetic association study of the DRD4 VNTR and the activity-impulsivity dimension of the recently validated dog-ADHD Rating Scale. To avoid false positives arising from population stratification, a single breed of dogs (German shepherd) was studied. Two DRD4 alleles (referred to as 2 and 3a ) were detected in this breed, and genotype frequencies were in Hardy–Weinberg equilibrium. For modelling distinct environmental conditions, 'pet' and 'police' German shepherds were characterized. Police German shepherds possessing at least one 3a allele showed significantly higher scores in the activity-impulsivity dimension of the dog-ADHD Rating Scale than dogs without this allele ( P  = 0.0180). This difference was not significant in pet German shepherds. To the best of our knowledge, this is the first report of an association between a candidate gene and a behaviour trait in dogs, and it reinforces the functional role of DRD4 exon 3 polymorphism.     

Candidate gene studies of ADHD: a meta-analytic review

Quantitative genetic studies (i.e., twin and adoption studies) suggest that genetic influences contribute substantially to the development of attention deficit hyperactivity disorder (ADHD). Over the past 15 years, considerable efforts have been made to identify genes involved in the etiology of this disorder resulting in a large and often conflicting literature of candidate gene associations for ADHD. The first aim of the present study was to conduct a comprehensive meta-analytic review of this literature to determine which candidate genes show consistent evidence of association with childhood ADHD across studies. The second aim was to test for heterogeneity across studies in the effect sizes for each candidate gene as its presence might suggest moderating variables that could explain inconsistent results. Significant associations were identified for several candidate genes including DAT1, DRD4, DRD5, 5HTT, HTR1B, and SNAP25. Further, significant heterogeneity was observed for the associations between ADHD and DAT1, DRD4, DRD5, DBH, ADRA2A, 5HTT, TPH2, MAOA, and SNAP25, suggesting that future studies should explore potential moderators of these associations (e.g., ADHD subtype diagnoses, gender, exposure to environmental risk factors). We conclude with a discussion of these findings in relation to emerging themes relevant to future studies of the genetics of ADHD.     

Joint analysis of the DRD5 marker concludes association with attention-deficit/hyperactivity disorder confined to the predominantly inattentive and combined subtypes

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable, heterogeneous disorder of early onset, consisting of a triad of symptoms: inattention, hyperactivity, and impulsivity. The disorder has a significant genetic component, and theories of etiology include abnormalities in the dopaminergic system, with DRD4, DAT1, SNAP25, and DRD5 being implicated as major susceptibility genes. An initial report of association between ADHD and the common 148-bp allele of a microsatellite marker located 18.5 kb from the DRD5 gene has been followed by several studies showing nonsignificant trends toward association with the same allele. To establish the postulated association of the (CA)(n) repeat with ADHD, we collected genotypic information from 14 independent samples of probands and their parents, analyzed them individually and, in the absence of heterogeneity, analyzed them as a joint sample. The joint analysis showed association with the DRD5 locus (P=.00005; odds ratio 1.24; 95% confidence interval 1.12-1.38). This association appears to be confined to the predominantly inattentive and combined clinical subtypes.     

Genetic associations between ADHD and dopaminergic genes (<Emphasis Type="Italic">DAT1</Emphasis> and <Emphasis Type="Italic">DRD4</Emphasis>) VNTRs in Korean children

It is well known that dopaminergic genes affect the development of attention deficit hyperactivity disorder (ADHD) in various populations. Many studies have shown that variable number tandem repeats (VNTRs) located within the 3′-untranslated region of DAT1 and in exon 3 of DRD4 are associated with ADHD development; however, these results were inconsistent. Therefore, we investigated the genetic association between two VNTRs and ADHD in Korean children. We determined the VNTRs using PCR. We examined genotype and allele frequency differences between the experimental and control groups, along with the odds ratios, using Chi square and exact tests. We observed a significant association between the children with ADHD and the control group in the 10R/10R genotype of DAT1 VNTRs (p?=?0.025). In addition, the 11R allele of DAT1 VNTRs showed a higher frequency in the control group than in the ADHD group (p?=?0.023). Also, the short repeat (without 11R) and long repeat alleles (including 11R) were associated with ADHD (p?<?0.05). The analysis of DRD4 VNTRs revealed that the 2R allele is associated with ADHD (p?=?0.025). A significant result was also observed in long and short repeats (p?<?0.05). Additionally, ADHD subtypes showed that the DRD4 VNTRs are associated with combined and hyperactive-impulsive subtype groups (p?<?0.05). Therefore, our results suggest that DAT1 VNTRs and DRD4 VNTRs play a role in the genetic etiology of ADHD in Korean children.     

DRD4 Rare Variants in Attention-Deficit/Hyperactivity Disorder (ADHD): Further Evidence from a Birth Cohort Study

The dopamine receptor D4 (DRD4) is one of the most studied candidate genes for Attention-Deficit/Hyperactivity Disorder (ADHD). An excess of rare variants and non-synonymous mutations in the VNTR region of 7R allele in ADHD subjects was observed in previous studies with clinical samples. We hypothesize that genetic heterogeneity in the VNTR is an important factor in the pathophysiology of ADHD. The subjects included in the present study are members of the 1993 Pelotas Birth Cohort Study (N=5,249). We conducted an association study with the 4,101 subjects who had DNA samples collected. The hyperactivity-inattention scores were assessed through the parent version of the Strengths and Difficulties Questionnaire at 11 and 15 years of age. The contribution of allele’s length and rare variants to high hyperactivity/inattention scores predisposition was evaluated by multivariate logistic regression. No effect of allele length was observed on high scores of hyperactivity-inattention. By contrast, when resequencing/haplotyping was conducted in a subsample, all 7R rare variants as well as non-synonymous 7R rare variants were associated with high hyperactivity/inattention scores (OR=2.561; P=0.024 and OR=3.216; P=0.008 respectively). A trend for association was observed with 4R rare variants. New coding mutations covered 10 novel motifs and many of them are previously unreported deletions leading to different stop codons. Our findings suggest a contribution of DRD4 7R rare variants to high hyperactivity-inattention scores in a population-based sample from a large birth cohort. These findings provide further evidence for an effect of DRD4 7R rare variants and allelic heterogeneity in ADHD genetic susceptibility.     

The association between dopamine receptor (DRD4) gene polymorphisms and second language learning style and behavioral variability in undergraduate students in Turkey

The dopamine D4 receptor gene (DRD4) encodes a receptor for dopamine, a chemical messenger used in the brain. One variant of the DRD4 gene, the 7R allele, is believed to be associated with attention deficit hyperactivity disorder (ADHD). The aim of this study was to investigate the relationships between repeat polymorphisms in dopamine DRD4 and second language learning styles such as visual (seeing), tactile (touching), auditory (hearing), kinesthetic (moving) and group/individual learning styles, as well as the relationships among DRD4 gene polymorphisms and ADHD in undergraduate students. A total of 227 students between the ages of 17–21 years were evaluated using the wender utah rating scale and DSM-IV diagnostic criteria for ADHD. Additionally, Reid's perceptual learning style questionnaire for second language learning style was applied. In addition, these students were evaluated for social distress factors using the list of Threatening Events (TLE); having had no TLE, having had just one TLE or having had two or more TLEs within the previous 6 months before the interview. For DRD4 gene polymorphisms, DNA was extracted from whole blood using the standard phenol/chloroform method and genotyped using polymerase chain reaction. Second language learners with the DRD4.7+ repeats showed kinaesthetic and auditory learning styles, while students with DRD4.7-repeats showed visual, tactile and group learning, and also preferred the more visual learning styles \(\left( {\bar{X}:{ 3}. 70} \right)\) . We also demonstrated that the DRD4 polymorphism significantly affected the risk effect conferred by an increasing level of exposure to TLE.     

Genetic polymorphism in dopamine receptor D4 is associated with early body condition in a large population of greater flamingos, Phoenicopterus roseus

Body condition is an important determinant of fitness in many natural populations. However, as for many fitness traits, the underlying genes that regulate body condition remain elusive. The dopamine receptor D4 gene (DRD4) is a promising candidate as dopamine is known to play an important role in the regulation of food intake and the metabolism of both glucose and lipids in vertebrates. In this study, we take advantage of a large data set of greater flamingos, Phoenicopterus roseus, to test whether DRD4 polymorphism predicts early body condition (EBC) while controlling for whole-genome effects of inbreeding and outbreeding using microsatellite multilocus heterozygosity (MLH). We typed 670 of these individuals for exon 3 of the homologue of the human DRD4 gene and 10 microsatellite markers. When controlling for the effects of yearly environmental variations and differences between sexes, we found strong evidence of an association between exon 3 DRD4 polymorphisms and EBC, with 2.2-2.3% of the variation being explained by DRD4 polymorphism, whereas there was only weak evidence that MLH predicts EBC. Because EBC is most likely a polygenic trait, this is a considerable amount of variation explained by a single gene. This is to our knowledge, the first study to show an association between exon 3 DRD4 polymorphism and body condition in non-human animals. We anticipate that the DRD4 gene as well as other genes coding for neurotransmitters and their receptors may play an important role in explaining variation in traits that affect fitness.     

Preferential transmission of paternal alleles at risk genes in attention-deficit/hyperactivity disorder

Family, twin, and adoption studies have demonstrated a significant genetic contribution to the etiology of attention-deficit/hyperactivity disorder (ADHD). Pharmacological, neuroimaging, and animal-model findings suggest imbalances in monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in ADHD. We have examined monoaminergic candidate genes for possible genetic association with ADHD in the Irish population, focusing particularly on genes of the dopaminergic and serotonergic systems. We have observed that several of these genes are associated with ADHD, including DAT1, DBH, DRD4, DRD5, and 5HT1B. Here, we present what appears to be a systematic overtransmission of paternal alleles at candidate genes associated with ADHD. For the nine genes included in the analysis, the overall odds ratio for paternal transmission was 2, compared with 1.3 for maternal transmission (paternal vs. maternal chi 2=9.6; P=.0019). Transmission to females, from either parent, was significantly stronger than to males. Possible reasons for this preferential transmission include imprinting and ascertainment bias, although results of further analyses show that the latter is unlikely.     

Role of Dopamine Receptors in ADHD: A Systematic Meta-analysis

The dopaminergic system plays a pivotal role in the central nervous system via its five diverse receptors (D1-D5). Dysfunction of dopaminergic system is implicated in many neuropsychological diseases, including attention deficit hyperactivity disorder (ADHD), a common mental disorder that prevalent in childhood. Understanding the relationship of five different dopamine (DA) receptors with ADHD will help us to elucidate different roles of these receptors and to develop therapeutic approaches of ADHD. This review summarized the ongoing research of DA receptor genes in ADHD pathogenesis and gathered the past published data with meta-analysis and revealed the high risk of DRD5, DRD2, and DRD4 polymorphisms in ADHD.     

DRD4 and TH gene polymorphisms are associated with activity,impulsivity and inattention in Siberian Husky dogs

Both dopamine receptor D4 (DRD4) exon 3 and tyrosine hydroxylase (TH) intron 4 repeat polymorphisms have been linked to activity and impulsivity in German Shepherd dogs (GSDs). However, the results in GSDs may not be generalisable to other breeds, as allelic frequencies vary markedly among breeds. We selected the Siberian Husky for further study, because it is highly divergent from most dog breeds, including the GSD. The study sample consisted of 145 racing Siberian Huskies from Europe and North America. We found that this breed possesses seven DRD4 length variants, two to five more variants than found in other breeds. Among them was the longest known allele, previously described only in wolves. Short alleles of the DRD4 and TH repeat polymorphisms were associated with higher levels of activity, impulsivity and inattention. Siberian Huskies possessing at least one short allele of the DRD4 polymorphism displayed greater activity in a behavioural test battery than did those with two long alleles. However, the behavioural test was brief and may not have registered variation in behaviour across time and situations. Owners also completed the Dog‐Attention Deficit Hyperactivity Disorder Rating Scale (Dog‐ADHD RS), a more general measure of activity and attention. Siberian Huskies from Europe with two short alleles of the TH polymorphism received higher ratings of inattention on the Dog‐ADHD RS than did those with the long allele. Investigation of the joint effect of DRD4 and TH showed that dogs possessing long alleles at both sites were scored as less active–impulsive than were others. Our results are aligned with previous studies showing that DRD4 and TH polymorphisms are associated with activity–impulsivity related traits in dogs. However, the prevalence of variants of these genes differs across breeds, and the functional role of specific variants is unclear.