儿茶酚氧位甲基转移酶基因多态性与焦虑症的相关性研究

目的 探讨儿茶酚氧位甲基转移酶(COMT)Val108/158Met基因多态性与焦虑症之间的关系.方法 采用聚合酶链反应一限制性片段长度多态性方法检测了176例焦虑症患者(患者组)和200名健康体检者(对照组)COMT Val108/158Met位点基因型,分析基因型和等位基因频率在2组间的分布差异,及其与患者临床症状表型之间的关系.患者均经汉密尔顿焦虑量表(HAMA)和症状自评定量表测评.结果 (1)患者组COMT 108/158Met/Met基因型和Met等位基因频率的分布为6.25%、26.99%,对照组为2.50%、18.75%,2组比较差异均有统计学意义(P均<0.05);患者组女性COMT 108/158Met/Met基因型和Met等位基因频率的分布高于对照组女性,2组比较差异有统计学意义(P<0.05);患者组男性COMT 108/158Met/Met基因型和Met等位基因频率的分布与对照组男性比较,差异无统计学意义(P>0.05).(2)患者组内COMT 108/158Met/Met基因型和携带Met等位基因患者HAMA总分、焦虑和恐怖因子分值分别高于其他基因型和携带Val等位基因患者(P均<0.05).结论 携带COMT Met108/158女性可能更易患焦虑症,COMT Met108/158与临床焦虑和恐怖程度有关.

Abstract：

Objective To explore the relationship of the Val108/158Met polymorphism of Catechol-O-methyl transferase(COMT)gene and anxiety in Han population.Methods The COMT Val108/158Metpolymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism(PCRRFLP)among 176 patients and 200 health subjects.The clinical symptom phenotypes data were obtained by assessing the HAMA and SCL-90 in anxiety patients.Results The distribution frequencies of Met/Met genotype and Met allele were 6.25%.2.50%and 26.99%.18.75%in patients and controls,respectively.Both distribution frequencies were significantly different in two groups,especially in females (P<0.05),and no significant difference was in males between two groups(P>0.05).Following analyzing the clinical symptom phenotypes,the patients with COMT 108/158Met/Met genotype or Met allelic locus had higher HAMA,SCL-90 anxiety and phobic scores than those with other genotypes or Val allelic locus (P<0.05).Conclusion The female individuals with COMT Met108/158 polymorphism may have higher susceptibility to anxiety,and be associated with clinical symptom phenotypes of anxiety.     

多巴胺转运体基因多态性与Tourette综合征疗效的相关性研究

目的 探讨不同疗效的Tourette综合征(TS)患者多巴胺转运体(DAT1)基因40 bp可变串联重复序列(VNTR)多态性分布频率是否存在差异.方法 应用聚合酶链反应-可变串联重复序列多态性分析技术,检测普通TS组(52例)、难治性TS组(63例)和正常对照组(57例)DAT1基因40 bp VNTR多态性;根据自制的临床资料调查表和耶鲁综合抽动严重程度量表(YGTSS)收集患者临床资料,使用美国精神障碍诊断与统计手册第4版(DSM-Ⅳ)Tourette综合征诊断标准进行诊断.结果 正常对照组、普通TS组和难治性TS组DAT1基因40 bp VNTR基因型频率分布差异无统计学意义(χ2=12.638,P=0.125);难治性TS组等位基因440 bp频率为8,高于普通TS组及正常对照组(1、0),但差异无统计学意义(χ2=11.352,P=0.053).结论 难治性TS中DAT1基因40 bp VNTR 440 bp等位基因出现频率较高,普通TS与难治性TS遗传机制可能存在差异,但需扩大样本含量进一步验证.

Abstract：

Objective To study the difference of dopamine transporter ( DAT1 )gene 40 bp variable number of tandem repeat ( VNTR ) genotype and allele frequency in TS patients with different curative effect in Chinese Han population. Methods In this study, the 40 bp polymorphism in the DAT1 gene was analyzed by using polymerase chain reaction-variable number of tandem repeat and polymorphism. The clinical data and tic symptoms was assessed with the clinical data schedule table and the Yale Global Tic Severity Scale ( YGTSS ). TS was diagnosed with the Diagnostic and Statistical Manual of Mental Disorders,the Forth Edition( DSM-Ⅳ )diagnostic criteria for Tourette syndrome. Results There was no significant differences in the frequencies of genotype for DAT1 gene 40 bp VNTR between normal controls ( 57 samples )and common TS children ( 52 samples ) and refractory TS children ( 63 samples ) (χ2 = 12. 638, P =0.125).The allele 440bp tended to be more in children with refractory TS(refractory TS:commmon TS:normal controls=8:1:0),but with no significat differences(χ2=11.352,P=0.053).Conclusions The DAT1 gene 40 bp VNTR 440 bp allele frequency seems to be higher in children with refractory TS,which suggests common TS and refractory TS have different genetic background. It should be verified by making larger samples in future study.     

Morphological changes in gray matter volume correlate with catechol-O-methyl transferase gene Val158Met polymorphism in first-episode treatment-nave patients with schizophrenia

The catechol-O-methyltransferase(COMT) gene is a schizophrenia susceptibility gene. A common functional polymorphism of this gene,Val158/158 Met,has been proposed to influence gray matter volume(GMV). However,the effects of this polymorphism on cortical thickness/surface area in schizophrenic patients are less clear. In this study,we explored the relationship between the Val158 Met polymorphism of the COMT gene and the GMV/ cortical thickness/cortical surface area in 150 firstepisode treatment-nave patients with schizophrenia and 100 healthy controls. Main effects of diagnosis were found for GMV in the cerebellum and the visual,medial temporal,parietal,and middle frontal cortex. Patients with schizophrenia showed reduced GMVs in these regions. And main effects of genotype were detected for GMV in the left superior frontal gyrus. Moreover,a diagnosis × genotype interaction was found for the GMV of the left precuneus,and the effect of the COMT gene on GMV was due mainly to cortical thickness rather than cortical surface area. In addition,a pattern ofincreased GMV in the precuneus with increasing Met dose found in healthy controls was lost in patients with schizophrenia. These findings suggest that the COMTMet variant is associated with the disruption of dopaminergic influence on gray matter in schizophrenia,and the effect of the COMT gene on GMV in schizophrenia is mainly due to changes in cortical thickness rather than in cortical surface area.     

多巴胺转运体基因多态性与Tourette综合征疗效的相关性研究

Objective To study the difference of dopamine transporter ( DAT1 )gene 40 bp variable number of tandem repeat ( VNTR ) genotype and allele frequency in TS patients with different curative effect in Chinese Han population. Methods In this study, the 40 bp polymorphism in the DAT1 gene was analyzed by using polymerase chain reaction-variable number of tandem repeat and polymorphism. The clinical data and tic symptoms was assessed with the clinical data schedule table and the Yale Global Tic Severity Scale ( YGTSS ). TS was diagnosed with the Diagnostic and Statistical Manual of Mental Disorders,the Forth Edition( DSM-Ⅳ )diagnostic criteria for Tourette syndrome. Results There was no significant differences in the frequencies of genotype for DAT1 gene 40 bp VNTR between normal controls ( 57 samples )and common TS children ( 52 samples ) and refractory TS children ( 63 samples ) (χ2 = 12. 638, P =0.125).The allele 440bp tended to be more in children with refractory TS(refractory TS:commmon TS:normal controls=8:1:0),but with no significat differences(χ2=11.352,P=0.053).Conclusions The DAT1 gene 40 bp VNTR 440 bp allele frequency seems to be higher in children with refractory TS,which suggests common TS and refractory TS have different genetic background. It should be verified by making larger samples in future study.     

COMT基因rs4680位点与中国汉族人群帕金森病遗传易患性关联性分析

目的 探讨儿茶酚胺氧位甲基转移酶(COMT)基因rs4680位点Val158Met多态性与帕金森病遗传易患性的相关性.方法 采用聚合酶链反应-连接酶检测反应(polymerase chain reaction-ligase detection reaction,PCR-LDR)基因多态性测序方法,分析COMT rs4680位点基因型及等位基因频率在帕金森病患者(437例)和健康对照者(530人)间的分布差异.结果 帕金森病患者G等位基因频率为77.2％,A等位基因频率为22.8％,而在健康对照者分别为74.7％、25.3％,两组间COMTrs4680位点Val158Met等位基因频率分布差异没有统计学意义(P =0.199).各基因型频率在帕金森病患者分别为G/G型57.4％、G/A型39.6％、A/A型3.0％,在健康对照者分别为54.9％、39.6％、5.5％,两组间基因型频率分布差异无统计学意义(P=0.156).在校正性别、年龄混杂因素后经二元Logistic回归分析,COMT rs4680位点各基因型与帕金森病发病风险之间仍无相关性.结论 COMT基因r4680位点Val158Met多态性与中国汉族人群帕金森病易患性可能无关,进一步扩大样本量及在其他不同种族中的研究能更好地确定COMT rs4680位点Val158Met多态性在帕金森病发病风险中的作用.     

注意缺陷多动障碍患儿智商与儿茶酚-O-甲基转移酶基因及其它影响因素的研究

目的 探讨儿茶酚-O-甲基转移酶(COMT)基因Val158Met(rs4680)多态性及其它相关因素对注意缺陷多动障碍(ADHD)智商的影响.方法 对238例ADHD男性患儿进行韦氏智力测评和COMT基因Val158Met多态性的检测.比较高活性COMT基因型(VMVM)组和中低活性基因型(ValMet和MetMet)组间智商的差异,同时对影响智力的相关因素进行多元线性回归分析.结果 高活性基因型组的总智商(FIQ)和操作智商(PIQ)明显高于中低活性基因型组(t:1.98,P=0.049;t=1.99,P=0.048).按父母的受教育程度相应地将患儿分为3组:初中及以下组(第1组),高中以上组(第2组),大学本科及以上组(第3组).结果 显示,以父亲的受教育程度分组时,3个患儿组FIQ及VIQ的差异有统计学意义(F=3.36,P=0.04;F=4.33,P=0.01);以母亲的受教育程度分组时,3个患儿组F1Q、VIQ及PIQ的差异均有统计学意义(F=7.69,P=0.001;F=7.41,P=0.001;F=4.95,P=0.008).结果 显示,随父母文化程度升高患儿的IQ升高.经多因素分析,COMT基因型和母亲受教育程度进入回归方程,二者对患儿的FIQ有影响(P值为0.04和0.03).结论 提示COMT基因Vai158Met多态性及母亲的受教育程度与ADHD男性患儿的智商相关,尚需要进一步扩大样本量进行验证.     

COMT基因多态性与慢性精神分裂症患者认知功能的相关性研究

目的:探讨上海汉族人口中儿茶酚胺氧位甲基转移酶(COMT)基因Val108/158Met多态性与慢性精神分裂症患者认知功能的关系。方法:采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术对152例慢性精神分裂症患者COMT基因多态性进行检测,并选用连线测验(TMT)、韦氏记忆测验(WMS)、威斯康星卡片分类测验(WCST)对其认知功能进行评定。结果:COMT基因与TMT成绩显著相关,其中高活性G/G基因型患者B部分成绩显著低于低活性A/A基因型患者。COMT基因与WMS成绩显著相关,其中G/G基因型患者记忆商数分、背数分显著低于A/A基因型患者。COMT基因与WCST成绩无显著相关性。结论:COMT基因与慢性精神分裂症患者认知功能具有显著相关性,其中高活性G/G基因型患者认知损害更明显。     

脑源性神经营养因子基因多态性与重性抑郁障碍认知功能的关系

目的 探讨脑源性神经营养因子(BDNF)基因Va166Met多态性与重性抑郁障碍认知功能的关系.方法 以100例重性抑郁障碍患者(患者组)与100名健康志愿者(对照组)为研究对象,采用1组神经心理学检测评估认知功能,并检测BDNF基因多态性;分别按照总智商(FIQ)、威斯康星卡片分类测验改良版(M-WCST)分类数、正确数、持续错误数、河内塔测试(TOH)计划时间、执行时间及总分的测验成绩由好到差排序,将患者组分为组1(成绩前50例,认知功能较好的患者)和组2(成绩后50例,认知功能较差的患者),检测组1与组2 BDNF基因型频率分布.结果 (1)对照组:除数字广度外,其他神经心理学测验成绩在BDNF基因型间的差异均无统计学意义(P>0.05).(2)患者组:中国修订韦氏成人智力量表(WAIS-RC)FIQ[(102.1±11.5)分vs(92.5±10.2)分]、M-WCST分类数[(5.6±1.7)分vs(2.9±1.2)分]和正确数[(36.5±6.0)分vs(26.8±5.6)分]、TOH总分[(50.8±9.6)分vs(40.4±9.3)分]及各项测验成绩,连线测验(TMT)A耗时数和B耗时数的成绩在患者组Val/Val基因型均优于Met/Met基因型,差异有统计学意义(P均<0.01).(3)组1Met/Met基因型频率分布显著低于组2,差异均有统计学意义(P均<0.01);除FIQ和TOH执行时间外,其他各项组1 Val/Val基因型频率显著高于组2,差异有统计学意义(P均<0.05).结论 BDNF基因Va166Met多态性与重性抑郁障碍患者认知功能损害可能有关.

Abstract：

objective To investigate relationship between brain-derived neurotrophic factor (BDNF)gene Va166Met polymorphism and cognitive function in patients with major depressive disorder.Methods One hundred patients with major depressive disorder and 100 healthy volunteers were included.The cognitive function was assessed by a series of neuropsychology tests,and BDNF gene polymorphism was detected.Results (1)In control group,the achievements of all neuropsychology tests except for digit span were not significantly different among ones with different BDNF genotypes(P>0.05).(2)In patient group,the achievements of neuropsychology tests such as WAIS-RC(102.1±1 1.5 vs.92.5±10.2),M-WCST(5.6±1.7 vs.2.9±1.2,36.5±6.0 vs.26.8±5.6),TOH(50.8±9.6 vs.40.4±9.3),time for TMT-A and TMT-B,were significantly better in ones with Val/Val genotype than in ones with Met/Met genotype(P≤0.01).(3)The Val/Val genotype frequency in patients with better cognitive function was higher than that in patients with worse cognitive function,while Met/Met genotype frequency was in the opposite direction(P<0.05 or P<0.01).Conclusion The BDNF gene Va166Met polymorphism is possibly correlated with impairment of cognitive function in patients with major depressive disorder.     

天津地区汉族人群COMT基因多态性与脑梗死相关性研究

研究背景儿茶酚胺氧位甲基转移酶(COMT)是儿茶酚胺的主要代谢酶,催化儿茶酚胺第3位羟基甲基化,降解儿茶酚胺,同时亦是雌激素的主要代谢酶。COMT基因在rs4680位点存在鸟嘌呤腺嘌呤(G-A)点突变,使其编码的第108和(或)158位氨基酸由缬氨酸(Val)变为蛋氨酸(Met),导致儿茶酚胺氧位甲基转移酶活性降低。已知COMT基因多态性与精神疾病、酒精依赖、药物不良反应等有关,而与脑梗死之间的关系尚不明确,本研究旨在探讨COMT基因多态性与脑梗死之间的关系。方法通过聚合酶链反应限制性酶切片段长度多态性方法检测181例天津地区汉族脑梗死患者COMT Val及Met基因型,以及不同基因型脑梗死患者血糖、总胆固醇、甘油三酯、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇,以及载脂蛋白A和B水平。结果脑梗死组Val等位基因频率(78.45%)及Val/Val纯合子基因型(61.33%)均高于正常对照组(68.24%和45.95%),差异具有统计学意义(P<0.05);进一步分析显示男性Val等位基因频率(82.52%)与正常对照组(66.67%)之间差异亦存在统计学意义(P<0.01),而女性患者组间差异(69.83%对69.07%)无统计学意义(P>0.05)。脑梗死组Val/Val型与Val/Met+Met/Met型比较,血糖、血脂水平及高血压患病率差异无统计学意义(均P>0.05)。结论 COMT Val等位基因频率和Val/Val纯合子基因型是男性脑梗死患者的遗传学危险因素,COMT对脑梗死的影响与血糖、血脂及血压无明显相关性。     

儿茶酚氧位甲基转移酶基因与注意缺陷多动障碍患儿认知功能的关联研究

目的 探讨儿茶酚氧位甲基转移酶(COMT)基因Va1108/158Met(rs4680)多态性对注意缺陷多动障碍(ADHD)患儿认知功能的影响.方法 对203例中国汉族ADHD患儿进行韦氏记忆测查、Stroop测验及数字划消测查,评定记忆力、反应抑制能力和注意力,并检测COMT基因Va1158Met多态性.按照基因型将样本分为高活性基因型组(92例,ValVal)和中低活性基因型组(111例,ValMet和MetMet),比较两组间各项测查结果的异同.结果 高活性基因型组图片分测验[(11.7±3.1)分]和Stroop测验C部分错误数(0个)的成绩好于中低活性基因型组[分别为(10.8±2.9)分和1个;P＜0.05～0.01].两组其他方面的差异均无统计学意义.结论 COMT基因Val158Met多态性与ADHD患儿的认知功能中的记忆力、反应抑制能力和注意力相关.     

Performance on the Wisconsin Card Sorting Test in schizophrenia and genes of dopaminergic inactivation (COMT, DAT, NET)

The aim of the study was to test an association between polymorphisms of genes connected with dopaminergic inactivation in prefrontal cortex [catechol-O-methyltransferase (COMT), dopamine transporter (DAT), norepinephrine transporter (NET)], and performance on the Wisconsin Card Sorting Test (WCST), in schizophrenic patients. The number of perseverative errors (WCST-P), non-perseverative errors (WCST-NP), completed corrected categories (WCST-CC), conceptual level responses (WCST-%CONC) and set to the first category (WCST-1st CAT) were measured. Genotyping was done for the Val108(158)Met polymorphism of the COMT gene (79 patients), the 3'UTR VNTR polymorphism of the DAT gene (124 patients) and the 1287 A/G polymorphism of the NET gene (63 patients). Male schizophrenic patients with Val/Val genotype of COMT obtained better results on WCST-P, while female patients had worse results on the WCST-NP compared with the remaining genotypes. There was a slight trend for patients with the A9/A9 genotype of DAT and with the A/A genotype of NET to perform better on some domains of the WCST, compared with other genotypes. A limitation to the interpretation of results could be small number of patients studied as well as variable psychopathological state and medication during cognitive testing.     

A quantitative association study between schizotypal traits and COMT, PRODH and BDNF genes in a healthy Chinese population

Previous studies have suggested that catechol-O-methyltransferase (COMT), proline dehydrogenase (PRODH), and brain-derived neurotrophic factor (BDNF) genes are possible susceptibility genes for schizophrenia. We hypothesized that these genes are also associated with schizotypal traits, which are heritable and related to schizophrenia. We genotyped five single nucleotide polymorphism (SNPs) from the COMT, PRODH and BDNF genes, and performed a series of association analyses between alleles, genotypes or haplotypes, and quantitative schizotypal trait scores derived from the Schizotypal Personality Questionnaire (SPQ), in 465 Chinese healthy subjects. We found that 'years of education' was a major influence on seven out of nine schizotypal components, three schizotypal factors and the total SPQ scores. Molecular genetic analysis of COMT, PRODH and BDNF genes showed no significant effects of any variants on schizotypal components or factors of SPQ after correction for multiple testing, although there were weak association between COMT Val158Met (rs4680G/A) and the odd speech subscale (allele-wise, P=0.04; genotype-wise, P=0.049), between COMT Val158Met (rs4680G/A) and the suspiciousness subscale (genotype-wise, P=0.024), and between BDNF Val66Met and the Factor 2 interpersonal measure (genotype-wise, P=0.027) before correction. Furthermore, we found SNP Val158Met (rs4680) of the COMT gene significantly influenced the scores of some of schizotypal traits including total SPQ score, the disorganization factor and the constricted affect subscale in male subjects only. However, the effect was in the opposite direction of an earlier association with the SPQ reported by Avramopoulos et al. [Avramopoulos, D., Stefanis, N.C., Hantoumi, I., Smyrnis, N., Evdokimidis, I., Stefanis, C.N., 2002. Higher scores of self reported schizotypy in healthy young males carrying the COMT high activity allele. Molecular Psychiatry 7, 706-711]. We conclude that SNP Val158Met (rs4680) in the COMT gene may be associated with some schizotypal traits in male subjects, but our results are not conclusive.     

Gender effect of catechol-O-methyltransferase Val158Met polymorphism on suicidal behavior

Genetic factors and catecholaminergic dysfunction have been suggested as the etiology of suicide. The catechol-O-methyltransferase (COMT) 158Val/Met polymorphism affects COMT activity; that is, the alleles encoding Val and Met are associated with relatively high and relatively low COMT activity, respectively. We aimed to identify the role of the COMT Val158Met polymorphism in suicidal attempt behavior. The COMT 158Val/Met polymorphisms were analyzed in 197 suicide attempters (male/female: 70/127), 170 control subjects (male/female: 85/85). All subjects were ethnic Korean. The Lethality Suicide Attempt Rating Scale (LSARS) and risk-rescue rating (RRR) system were explored. For the male subjects, there was a significant difference in genotype distributions and allele frequencies between control subjects and suicide attempters. That is, Val/Val genotype and Val carriers were more frequent in suicide attempters than in control subjects. For the female subjects, however, no significant difference was shown in genotype distributions and allele frequencies between control subjects and suicide attempters. There were no significant differences in LSARS and RRR according to the genotypes. The distribution of the COMT 158Val/Met polymorphism showed a biologically meaningful difference between control subjects and suicide attempters among the male subjects although selection bias should be considered.     

Schizotypy, attention deficit hyperactivity disorder, and dopamine genes

Previous research has suggested that there may be overlap between schizophrenia and attention-deficit hyperactivity disorder (ADHD). The relationship between schizotypal personality traits, ADHD features and polymorphisms was evaluated in dopamine-related genes. Thirty-one healthy, Caucasian men completed the Rust Inventory of Schizotypal Cognitions (RISC) and the ADHD Self-Report Scale (ASRS). Catechol-O-methyltransferase (COMT) Val158Met, dopamine receptors of the D3 type (DRD3) Ser9Gly, DRD4 variable number of tandem repeats (VNTR), and SLC6A3 VNTR polymorphisms were analyzed. RISC score was correlated with ASRS score (r = 0.54, P = 0.003). COMT Met homozygotes had higher ASRS scores than Val homozygotes (P = 0.005). These findings are consistent with evidence of overlap between schizophrenia and ADHD and support an involvement of COMT genotype in ADHD features.     

Gene-gene interaction between MAOA and COMT in suicidal behavior: analysis in schizophrenia

A large body of evidence suggests that suicidal behavior is associated with altered noradrenergic neurotransmission. Norepinephrine is degraded by monoamine oxidase A (MAOA) and catechol-O-methyl transferase (COMT). Our hypothesis is that the genes encoding MAOA and COMT might contain genetic variants conferring increased risk for suicidal behavior in schizophrenia and that both genes may interact each other. In order to test this hypothesis, we genotyped the promoter VNTR polymorphism in the MAOA gene and three COMT polymorphisms: -287A>G, Val/Met and 3'UTR C Ins/Del in a cohort of 270 schizophrenics in which 92 attempted suicide. No association between suicide attempt and the MAOA VNTR (P = 0.382), Val108/158Met (P = 0.788) or -287A>G (P = 0.420) polymorphisms was found, however, a slight significant finding was found for 3'UTR polymorphism (P = 0.050). Haplotype analysis for COMT gene revealed no association between suicide attempts and haplotype distribution (P = 0.451). As we tested for epistasis between MAOA VNTR and COMT Val/Met, we found no significant interaction in conferring risk for suicide attempts (P = 0.545). These results suggest that epistasis between MAOA and COMT genes may not influence suicidal behavior in patients with schizophrenia.     

Catechol-O-methyltransferase Val158Met genotype in healthy and personality disorder individuals: Preliminary results from an examination of cognitive tests hypothetically differentially sensitive to dopamine functions

A functional polymorphism of the gene coding for Catechol-O-methyltrasferase (COMT), an enzyme responsible for the degradation of the catecholamine dopamine (DA), epinephrine, and norepinephrine, is associated with cognitive deficits. However, previous studies have not examined the effects of COMT on context processing, as measured by the AX-CPT, a task hypothesized to be maximally relevant to DA function. 32 individuals who were either healthy, with schizotypal personality disorder, or non-cluster A, personality disorder (OPD) were genotyped at the COMT Val158Met locus. Met/Met (n = 6), Val/Met (n = 10), Val/Val (n = 16) individuals were administered a neuropsychological battery, including the AX-CPT and the N-back working memory test. For the AX-CPT, Met/Met demonstrated more AY errors (reflecting good maintenance of context) than the other genotypes, who showed equivalent error rates. Val/Val demonstrated disproportionately greater deterioration with increased task difficulty from 0-back to 1-back working memory demands as compared to Met/Met, while Val/Met did not differ from either genotypes. No differences were found on processing speed or verbal working memory. Both context processing and working memory appear related to COMT genotype and the AX-CPT and N-back may be most sensitive to the effects of COMT variation.     

Association study of COMT gene Val158Met polymorphism with auditory P300 and performance on neurocognitive tests in patients with schizophrenia and their relatives.

A number of studies have reported an association between catechol-O-methyltransferase (COMT) gene Val158Met polymorphism and neuropsychological traits in patients with schizophrenia, their relatives and healthy controls, with the Met allele carriers performing better on neurocognitive tasks than those with the Val allele. But the association was not confirmed in all studies. The present paper was aimed at further investigation of the COMT gene relationship with some neurocognitive traits, assessing mainly working and verbal memory, and to P300 event-related potentials (auditory oddball). A total sample of 319 individuals, including schizophrenic patients, their relatives and controls, was studied. No significant differences in performance of neurocognitive tasks were found by Val158Met genotypes. An association was observed between the Met/Met genotype and higher amplitude in centro-parietal area in relatives. Factors that could explain the non-replication of previous studies on the COMT gene polymorphism and neurocognitive traits are discussed. We suggest here that (1) Val158Met polymorphism rather exerts a modifying influence on brain activation in general than impacts directly on performance of the particular neurocognitive test, and (2) P300 amplitude seems to be a correlate of this activation reflecting, along with information processing, the subject's affective and personality features.