Association study of MAO-A, COMT, 5-HT2A, DRD2, and DRD4 polymorphisms with illness time course in mood disorders

The Repertoire of Small-Molecule PET Probes for Neuroinflammation Imaging: Challenges and Opportunities beyond TSPO

Neuroinflammation is an adaptive response of the central nervous system to diverse potentially injurious stimuli, which is closely associated with neurodegeneration and typically characterized by activation of microglia and astrocytes. As a noninvasive and translational molecular imaging tool, positron emission tomography (PET) could provide a better understanding of neuroinflammation and its role in neurodegenerative diseases. Ligands to translator protein (TSPO), a putative marker of neuroinflammation, have been the most commonly studied in this context, but they suffer from serious limitations. Herein we present a repertoire of different structural chemotypes and novel PET ligand design for classical and emerging neuroinflammatory targets beyond TSPO. We believe that this Perspective will support multidisciplinary collaborations in academic and industrial institutions working on neuroinflammation and facilitate the progress of neuroinflammation PET probe development for clinical use.

Meta-analysis of the COMT Val158Met polymorphism in major depressive disorder: the role of gender

OBJECTIVES

Many studies have reported an association of the COMT Val158Met polymorphism and major depressive disorder (MDD), although with conflicting results. The role of gender is a possible modulator. To overcome the problem of poor sample size detecting genes of small effect, we perform a meta-analysis of the current literature, investigating the influence of the COMT Val158Met polymorphism on the pathogenesis of MDD, with a major focus on the effect of gender.

METHODS

Out of 977 retrieved articles, 21 included case-control studies allowed the analysis of 9005 patients with MDD and 12,095 controls. Allelic and genotypic pooled odds ratios (OR) were calculated for the total sample and gender-subgroups.

RESULTS

In the absence of publication bias, allelic and genotypic analyses showed no significant association in the total sample, as well as in gender-specific subgroups. Sensitivity analysis did not alter the ORs.

CONCLUSIONS

The results imply a complex nature of the genotype × phenotype interaction. Further studies of the COMT gene or the locus remain to be justified given the important positional and functional relevance and the plethora of gender-specific findings. A possible way to further dissect this topic is shifting the focus to gene-based or genome-wide analyses of intermediate phenotypes.

The MAOA, COMT, MTHFR and ESR1 gene polymorphisms are associated with the risk of depression in menopausal women

OBJECTIVE

The aim of the study was assessment of a possible relationship between the polymorphisms of the candidate genes participating in the etiology of some neurological and psychiatric disorders and the risk of depression in perimenopausal and postmenopausal women.

METHODS

A total of 167 (54 perimenopausal and 113 postmenopausal) Caucasian women from western Poland, aged 42-67, were recruited as the patient group in the study because of depressive symptoms, and another 321 healthy women (102 perimenopausal and 219 postmenopausal) served as the controls. All study participants were evaluated for climacteric and depressive disorders according to the Kupperman index and Hamilton rating scale for depression (HRSD), respectively. The following candidate genes were selected for the study: 5HTR2A, 5HTR1B, 5HTR2C, TPH1, TPH2, MAOA, COMT, NET, GABRB1, ESR1, MTHFR, MTR and MTHFD1. In each group the frequencies of the polymorphisms were determined using PCR-RFLP analysis.

RESULTS

After correcting for Bonferroni multiple tests, we found associations between the MAOA c.1460C>T (SNP 1137070), COMT c.472G>A (SNP 4680), MTHFR c.677C>T (SNP 1801133) and ESR1 454(-351) A>G (SNP 9340799) polymorphisms to mild and moderate depressive symptoms in menopausal women. In the perimenopausal and postmenopausal women, genotype association of the MAOA c.1460 CT and c.1460 CT+TT (OR=1.83; pcorr=0.009 and OR=1.85; pcorr=0.003, resp.), and of the MTHFR c.677 TT and c.677 CT+TT (OR=3.52; pcorr=0.00009 and OR=2.06; pcorr=0.0006, resp.), as well as of the COMT c.472 GA and COMT c.472 GA+AA genotypes (OR=2.23; pcorr=0.03 and OR=2.17; pcorr=0.027, resp.) in the postmenopausal women revealed significantly higher frequencies of these variants in depressed female patients than in controls, whereas the ESR1 454(-351) AG and 454(-351) AG+GG genotypes were associated with lower risk of depression in postmenopausal women (OR=0.48; pcorr=0.012, and OR=0.52; pcorr=0.015, resp.).

CONCLUSIONS

Our study substantiates the involvement of the MAOA and MTHFR polymorphisms in climacteric depression and offers evidence that the COMT and ESR1 genes may also play a role in the susceptibility to depressive mood in postmenopausal women.

Relationship between the catechol-O-methyl transferase Val108/158Met genotype and brain volume in treatment-naive major depressive disorder: Voxel-based morphometry analysis

Catechol-O-methyltransferase (COMT) is a methylation enzyme engaged in the degradation of dopamine and noradrenaline by catalyzing the transfer of a methyl group from S-adenosylmethionine. An association was found between the Valine (Val) 108/158Methionine (Met) COMT polymorphism (rs4680) and major depressive disorder (MDD). The authors prospectively investigated the relationship between the Val108/158Met COMT genotype and voxel-based morphometry (VBM) findings for patients with first-episode and treatment-naïve MDD and healthy subjects (HS). Participants comprised 30 MDD patients and 48 age- and sex-matched HS who were divided according to the COMT genotype. Effects of diagnosis, COMT genotype, and the genotype-diagnosis interaction in relation to brain morphology in the Val/Met and Val/Val individuals were evaluated using a VBM analysis of high-resolution magnetic resonance imaging findings. Among the Val/Met individuals, the volume of the bilateral caudate was significantly smaller for MDD patients than for HS. In the Val/Val individuals, the caudate volume was comparable between MDD patients and HS. Significant genotype-diagnosis interaction effects on brain morphology were noted in the right caudate.

Association of COMT and TPH-2 genes with DSM-5 based PTSD symptoms

BACKGROUND

Dopaminergic and serotonergic systems have been implicated in PTSD. The present study evaluated the association of four catechol-O-methyltransferase (COMT) gene loci, and the joint effect of COMT and tryptophan hydroxylase 2 (TPH2) genes on PTSD symptoms.

METHODS

Subjects included 200 Caucasian Armenian adults exposed to the 1988 Spitak earthquake from 12 multigenerational (3-5 generations) families. Instruments used included the UCLA PTSD Reaction Index based on DSM-5 criteria, and the Beck Depression Inventory.

RESULTS

The adjusted heritabilitiy of vulnerability to DSM-5 based PTSD symptoms was 0.60 (p<10(-4)). There was a significant association of the COMT allele rs4633C with total PTSD (p<0.03), and D category (p<0.04) (negative alterations in cognitions and mood) severity scores, but not with C category (avoidance) scores. There was no genetic correlation between C and D category severity scores. COMT allele rs4633C and the TPH-2 allele rs11178997T together accounted for 7% of the variance in PTSD severity scores (p<0.001). None of the COMT alleles were associated with depression.

LIMITATIONS

The ratings of earthquake exposure and prior trauma may have been subject to recall bias. The findings may not be generalizable to other ethnic/racial populations.

CONCLUSION

COMT allele rs4633C may be causally related and/or is in linkage disequilibrium with gene(s) that are causally related to PTSD symptoms. Carriers of these COMT and the TPH-2 alleles may be at increased risk for PTSD. The findings provide biological support for dividing DSM-IV category C symptoms into DSM-5 categories C and D.

Lack of influence of rs4680 (COMT) and rs6276 (DRD2) on diagnosis and clinical outcomes in patients with major depression

OBJECTIVE

The gene coding for the catechol-O-methyltransferase (COMT) and the one coding for the dopamine receptor 2 (DRD2) have been linked with major depression (MD) and with the response to antidepressants in several studies. However, contrasting findings have been reported as well. The aim of the present study is, therefore, to investigate possible influences of rs4680 within COMT and rs6276 within DRD2, analyzed both individually and in combination, on the diagnosis and clinical outcomes in a sample of Korean MD patients treated with antidepressants.

METHODS

Totally, 184 Korean in-patients suffering from MD treated with either paroxetine or venlafaxine and 220 healthy control subjects were included in the present study. Depression severity was assessed by means of the Hamilton Rating Scale for Depression.

RESULTS

We were not able to find any association between the two variants under investigation and diagnosis of MD, as well as with antidepressant response.

CONCLUSIONS

Although limited by several factors, including the small sample size and the impossibility to extend our findings to patients treated with different antidepressants, the results of our study provide support to the notion that these variants might not play a major role in the etiology and clinical outcomes of MD.

The DRD2 rs1800497 polymorphism increase the risk of mood disorder: evidence from an update meta-analysis

BACKGROUND

Growing studies have revealed the association between rs1800497 polymorphism in the dopamine receptor D2 (DRD2) and susceptibility to mood disorder (MD). However, the results remained inconsistent.

METHODS

To assess the effect of DRD2 rs1800497 polymorphism on MD. We performed a meta-analysis based on eight case-control studies, including a total of 2097 MD cases and 1681 controls. Summary odds ratios (OR) and corresponding 95% confidence intervals (CIs) for DRD2 rs1800497 polymorphism and MD risk were estimated.

RESULTS

Our meta-analysis indicated that DRD2 rs1800497 was associated with an increased MD risk, especially in Asians. Moreover, in the subgroup analysis by the type of MD, DRD2 rs1800497 polymorphism was observed to increase risk in BP.

LIMITATIONS

The results should be treated with caution for lacking of data to perform gene-gene and gene-environment interaction.

CONCLUSIONS

Our results indicated that polymorphism in DRD2 rs1800497 may play a role in development of MD.

European Group for the Study of Resistant Depression (GSRD)--where have we gone so far: review of clinical and genetic findings

The primary objective of this review is to give an overview of the main findings of the European multicenter project "Patterns of Treatment Resistance and Switching Strategies in Affective Disorder", performed by the Group for the Study of Resistant Depression (GSRD). The aim was to study methodological issues, operational criteria, clinical characteristics, and genetic variables associated with treatment resistant depression (TRD), that is failure to reach response after at least two consecutive adequate antidepressant trials. The primary findings of clinical variables associated with treatment resistance include comorbid anxiety disorders as well as non-response to the first antidepressant received lifetime. Although there is a plethora of hints in textbooks that switching the mechanism of action should be obtained in case of nonresponse to one medication, the results of the GSRD challenge this notion by demonstrating in retrospective and prospective evaluations that staying on the same antidepressant mechanism of action for a longer time is more beneficial than switching, however, when switching is an option there is no benefit to switch across class. The GSRD candidate gene studies found that metabolism status according to cytochrome P450 gene polymorphisms may not be helpful to predict response and remission rates to antidepressants. Significant associations with MDD and antidepressant treatment response were found for COMT SNPs. Investigating the impact of COMT on suicidal behaviour, we found a significant association with suicide risk in MDD patients not responding to antidepressant treatment, but not in responders. Further significant associations with treatment response phenotypes were found with BDNF, 5HTR2A and CREB1. Additional investigated candidate genes were DTNBP1, 5HT1A, PTGS2, GRIK4 and GNB3.

The impact of COMT gene polymorphisms on suicidality in treatment resistant major depressive disorder--a European multicenter study

Many association studies have reported associations between the catechol-O-methyltransferase (COMT) gene and psychiatric disorders including major depression (MDD). The COMT gene has further been associated with suicidal behaviour, as well as with treatment response, although with conflicting results. In the present study, we further elucidate the impact of COMT in treatment response in MDD patients with suicide risk and/or a personal history of suicide attempts. Two hundred fifty MDD patients were collected in the context of a European multicentre resistant depression study and treated with antidepressants at adequate doses for at least 4 weeks. Suicidality was assessed using Mini International Neuropsychiatric Interview (MINI) and the Hamilton Rating Scale for Depression (HAM-D). Treatment response was defined as HAM-D ≤ 17 and remission as HAM-D ≤ 7 after 4 weeks of treatment with antidepressants at adequate dose. Genotyping was performed for seven SNPs (rs4680, rs2075507, rs737865, rs6269, rs4633, rs4818 and rs165599) within the COMT gene. With regard to suicide risk and personal history of suicide attempts, neither single marker nor haplotypic association was found with any SNP after multiple testing correction. In non-responders, we found significant single marker and haplotypic association with suicide risk, but not in responders. The same holds true for both remitters and non-remitters, and when testing for association with a personal history of suicide attempts and treatment response phenotypes. In conclusion, we found significant association of COMT SNPs with suicide risk in MDD patients not responding to antidepressant treatment. Larger well-defined cohorts will be required to dissect this further.

Association of DRD2 gene polymorphisms with mood disorders: a meta-analysis

BACKGROUND

In the past few decades, a number of studies have investigated the association of dopamine D2 receptor (DRD2) gene polymorphisms with mood disorders, but the findings are not always consistent. The aim of our study was to assess the association between DRD2 gene polymorphisms and mood disorders by using a meta-analysis.

METHODS

Data were collected from the following electronic databases: PubMed, Elsevier Science Direct, Cochrane Library, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, and Wanfang, with the last report up to June 2010. Meta-analysis was performed in a fixed/random effect model by using the software Review Manager 4.2.

RESULTS

We identified 19 separate studies using search, but only 14 separate studies (2157 cases and 3272 controls) were included in the current study. Meta-analysis was performed for three DRD2 gene polymorphisms (-141Cins/del, Ser311/Cys311, and TaqI A1). We performed meta-analysis in overall, Caucasian, and Asian populations. We also performed disease-specific meta-analysis in unipolar disorder and bipolar disorder. We found no association between DRD2 gene -141Cins/del polymorphism and mood disorders in overall and Caucasian populations (P>0.05). We also found no association between DRD2 gene Ser311/Cys311 polymorphism and mood disorders in overall, Caucasian, and Asian populations (P>0.05). An association of DRD2 gene TaqI A1 polymorphism with mood disorders was found in overall population, and the individuals with A1A1 genotype were more susceptible to mood disorders in comparison to those with A2A1 and A2A2 genotypes (OR=1.84, 95% CI=1.07-3.17, P=0.03).

LIMITATION

Meta-analysis is retrospective research that is subject to the methodological deficiencies of the included studies.

CONCLUSION

This meta-analysis suggests that mood disorders may be associated with DRD2 gene TaqI A1 polymorphism, but not -141Cins/del and Ser311/Cys311.

The functional Val158Met polymorphism in catechol-O-methyltransferase (COMT) is associated with depression and motivation in men from a Swedish population-based study

BACKGROUND

Environmental risk factors together with genetic vulnerability create a complex background to develop depression.

METHODS

We investigated the associations between COMT Val(158)Met and depression in a Swedish population-based sample of 405 depressed individuals (major depression diagnosis, dysthymia or mixed anxiety depression defined according to DSM-IV) and 2,151 healthy controls. We also analyzed interaction between this genetic variation and some environmental risk factors for depression and the link between this polymorphism and the low motivational level and negative mood state found in depressed individuals.

RESULTS

Depressed individuals displayed a higher frequency of the Met/Met and Met/Val genotypes compared to controls (OR=1.49, CI(95%)=1.11-2.00, P=0.009). The association was found among men only (OR=2.26, CI(95%)=1.26-4.05, p=0.008). Regression analysis including some potential risk factors for depression, did further indicate that Met/Met and Met/Val were associated with depression in men (P=0.005). There was also an interaction between genotype and family childhood problems (RERI=0.876, CI(95%)=0.090-1.662 and AP=0.426, CI(95%)=0.030-0.821). Further, depressed men homozygous for the Val-allele, had a higher motivational level than depressed men with a Met-variant (P=0.02).

LIMITATIONS

The sample size of depressed individuals per group when stratifying cases according to gender and genotypes is considered a limitation.

CONCLUSIONS

The Met-variants of COMT Val(158)Met are risk variants for depression and low motivational level in depressed Swedish men, but not women. Individuals with this risk variant in combination with a problematic childhood, have an even higher risk to develop depression.

Interaction of chronic stress with serotonin transporter and catechol-O-methyltransferase polymorphisms in predicting youth depression

BACKGROUND

Investigations of gene-environment interaction (GxE) in depression have implicated a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) as a moderator of the stress-depression relationship. However, recent evidence for 5-HTTLPR GxE in depression has been inconsistent. This study examined the moderating effect of the val158met polymorphism in the catechol-O-methyltransferase (COMT) gene on the strength of 5-HTTLPR GxE.

METHODS

A community sample of youth (n=384) was genotyped for 5-HTTLPR and COMT. A multi-method, multi-informant index of chronic family stress was derived from interviews and questionnaires administered at youth age 15. GxGxE was examined in relation to depression diagnoses between ages 15 and 20 and depressive symptoms at age 20.

RESULTS

Significant three-way interactions were observed for both depressive symptoms and diagnoses, such that 5-HTTLPR GxE occurred only in the context of COMT val158 allele homozygosity. For val158 homozygotes, the 5-HTTLPR LL genotype exerted a protective effect in the face of stress. No genetic main effect or two-way GxE was found for 5-HTTLPR.

CONCLUSIONS

Inconsistent 5-HTTLPR GxE findings to date may be partly attributable to unmeasured epistatic effects between 5-HTTLPR and COMT val158met. Identifying the conditions under which 5-HTTLPR GxE is most likely to operate may allow depression prevention and treatment efforts to target youth at highest risk.

Catechol-O-methyltransferase val108/158met genotype, major depressive disorder and response to selective serotonin reuptake inhibitors in major depressive disorder

The functional val108/158met polymorphism of the COMT gene (rs4680) was evaluated in major depressive disorder (MDD), and in the treatment response to antidepressants in MDD. We could not demonstrate any significant difference in the distribution of this COMT single-nucleotide polymorphism (SNP) in the treatment response to selective serotonin reuptake inhibitors or between patients with MDD and control subjects.

Association of monoamine oxidase A (MAOA) polymorphisms and clinical subgroups of major depressive disorders in the Han Chinese population

It has been proposed that an MAOA abnormality may be an important factor in the development of major depressive disorder (MDD). Various polymorphisms of the MAOA gene have been investigated for possible associations with mood disorders, but results have been inconsistent. The goal of the present study was to investigate whether polymorphisms of the MAOA gene are associated with MDD or alternatively with different clinical subgroups of MDD. A total of 590 Han Chinese subjects in Taiwan (312 controls and 278 MDD patients) were recruited. Among the males, there were no associations with MAOA polymorphisms. Among the females, an association was found between MAOA polymorphisms and severe MDD (P=0.041 for uVNTR and 0.017 for EcoRV (rs1137070), respectively). However, in analyses of haplotype frequencies and multiple logistic regression, MAOA polymorphisms were not associated with either MDD or its subgroups. The results suggest that MAOA polymorphisms do not play a major role in the pathogenesis of MDD or its subgroups. However, a potential role for a minor association with some specific subgroups and with different ethnic samples needs to be explored further.

COMT val158met influence on electroconvulsive therapy response in major depression

There is strong evidence for a genetic contribution to the pathogenesis of depression, with the functional catechol-O-methyltransferase (COMT) val158met polymorphism having been suggested as a potential susceptibility factor. In the present study, the effect of COMT val158met on response to electroconvulsive therapy (ECT) was analyzed in a sample of 104 Caucasian patients (f = 71, m = 33) with pharmacologically treatment-resistant Major Depression. The higher active COMT 158val allele was found to be associated with (1) higher pre-ECT severity of depression and (2) better treatment response to ECT particularly regarding the core symptoms of depression as well as sleep-related symptoms. These findings were restricted to the female subgroup of patients. In summary, the present study supports a potentially gender-specific significant impact of COMT gene variation on electroconvulsive therapy response, with COMT 158val risk allele carriers suffering from more severe, pharmacologically less efficiently treatable depression and thus possibly deriving greater benefit from ECT in the first place.

The role of dopamine in bipolar disorder

OBJECTIVE

Despite effective pharmacological treatments for bipolar disorder, we still lack a comprehensive pathophysiological model of the illness. Recent neurobiological research has implicated a number of key brain regions and neuronal components in the behavioural and cognitive manifestations of bipolar disorder. Dopamine has previously been investigated in some depth in bipolar disorder, but of late has not been a primary focus of attention. This article examines the role of dopamine in bipolar disorder, incorporating recent advances into established models where possible.

METHODS

A critical evaluation of the literature was undertaken, including a review of behavioural, neurochemical, receptor, and imaging studies, as well as genetic studies focusing on dopamine receptors and related metabolic pathways. In addition, pharmacologic manipulation of the central dopaminergic pathways and comparisons with other disease states such as schizophrenia were considered, principally as a means of exploring the hypothesised models.

RESULTS

Multiple lines of evidence, including data from pharmacological interventions and structural and functional magnetic resonance imaging studies, suggest that the dopaminergic system may play a central role in bipolar disorder.

CONCLUSION

Future research into the pathophysiological mechanisms of bipolar disorder and the development of new treatments for bipolar disorder should focus on the dopaminergic system.

The COMT Val158Met polymorphism and cognition in depressed and nondepressed older adults

OBJECTIVE

The objective of the current study was to examine the relationship between the COMT Val(158)Met polymorphism and neuropsychological performance in depressed and nondepressed older adults.

METHODS

One hundred and twenty-six clinically depressed older adults and 105 nondepressed comparison participants were compared on neuropsychological performance and COMT Val(158)Met (Val/Val, Val/Met, Met/Met).

RESULTS

Based on multivariate regression models, the COMT Val(158)Met polymorphism was not associated with cognitive performance among depressed or nondepressed individuals, nor did this polymorphism account for the fact that depressed individuals performed worse than nondepressed individuals on several neuropsychological tests that are typically affected by depression. There was also no difference in frequency of the COMT Val(158)Met alleles between depressed and nondepressed individuals.

CONCLUSIONS

Although the current study found no association between COMT Val(158)Met polymorphism on a number of clinical neuropsychological tests that are typically found to be sensitive to depression, differential effects of the COMT Val(158)Met polymorphism on dopamine transmission in psychiatric and non-psychiatric populations may be further clarified by clinical research with neuroscience-based paradigms that segregate cognitive tasks into component processes with precise neural substrates, particularly with respect to the complex functions of the prefrontal cortex. Negative results can be important to narrowing down target processes and understanding the influence of clinical and demographic characteristics in studies of psychiatric genetics.

Genetic and non-genetic influences on the development of co-occurring alcohol problem use and internalizing symptomatology in adolescence: a review

AIMS

Alcohol problem use during adolescence has been linked to a variety of adverse consequences, including cigarette and illicit drug use, delinquency, adverse effects on pubertal brain development and increased risk of morbidity and mortality. In addition, heavy alcohol-drinking adolescents are at increased risk of comorbid psychopathology, including internalizing symptomatology (especially depression and anxiety). A range of genetic and non-genetic factors have been implicated in both alcohol problem use as well as internalizing symptomatology. However, to what extent shared risk factors contribute to their comorbidity in adolescence is poorly understood.

DESIGN

We conducted a systematic review on Medline, PsycINFO, Embase and Web of Science to identify epidemiological and molecular genetic studies published between November 1997 and November 2007 that examined risk factors that may be shared in common between alcohol problem use and internalizing symptomatology in adolescence.

FINDINGS

Externalizing disorders, family alcohol problems and stress, as well as the serotonin transporter (5-HTT) S-allele, the monoamine oxidase A (MAOA) low-activity alleles and the dopamine D2 receptor (DDR2) Taq A1 allele have been associated most frequently with both traits. An increasing number of papers are focusing upon the role of gene-gene (epistasis) and gene-environment interactions in the development of comorbid alcohol problem use and internalizing symptomatology.

CONCLUSIONS

Further research in adolescents is warranted; the increasing availability of large longitudinal genetically informative studies will provide the evidence base from which effective prevention and intervention strategies for comorbid alcohol problems and internalizing symptomatology can be developed.

Association study of candidate variants of COMT with neuroticism, anxiety and depression

The Val158Met polymorphism of the gene encoding catechol-O-methyltransferase (COMT) is one of the most widely tested variants for association with psychiatric disorders, but replication has been inconsistent including both sex limitation and heterogeneity of the associated allele. In this study we investigate the association between three SNPs from COMT and anxiety and depression disorders and neuroticism all measured within the same study sample. Participants were selected as sibling pairs (or multiples) that were either concordant or discordant for extreme neuroticism scores from a total sample of 18,742 Australian twin individuals and their siblings. All participants completed the Composite International Diagnostic Interview (CIDI) from which diagnoses of DSM-IV depression and anxiety disorders were determined. Of the participants, 674 had a diagnosis of anxiety and/or depression from 492 families. Study participants (n = 2,045 from 987 families) plus, where possible, their parents were genotyped for rs737865, rs4680 (Val158Met), and rs165599. Using family based tests we looked for association between these variants and neuroticism, depression, anxiety, panic disorder and agarophobia (PDAG) and obsessive compulsive disorder. We found no convincing evidence for association either in allelic or genotypic tests for the total sample or when the sample was stratified by sex. Haplotype T-G-G showed weak association (P = 0.042) with PDAG before correction for multiple testing; association between this haplotype and schizophrenia has been previously reported in an Australian sample.

Meta-analyses of genetic studies on major depressive disorder

The genetic basis of major depressive disorder (MDD) has been investigated extensively, but the identification of MDD genes has been hampered by conflicting results from underpowered studies. We review all MDD case-control genetic association studies published before June 2007 and perform meta-analyses for polymorphisms that had been investigated in at least three studies. The study selection and data extraction were performed in duplicate by two independent investigators. The 183 papers that met our criteria studied 393 polymorphisms in 102 genes. Twenty-two polymorphisms (6%) were investigated in at least three studies. Seven polymorphisms had been evaluated in previous meta-analyses, 5 of these had new data available. Hence, we performed meta-analyses for 20 polymorphisms in 18 genes. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistically significant associations were found for the APOE varepsilon2 (OR, 0.51), GNB3 825T (OR, 1.38), MTHFR 677T (OR, 1.20), SLC6A4 44 bp Ins/Del S (OR, 1.11) alleles and the SLC6A3 40 bpVNTR 9/10 genotype (OR, 2.06). To date, there is statistically significant evidence for six MDD susceptibility genes (APOE, DRD4, GNB3, MTHFR, SLC6A3 and SLC6A4).

Association of the COMT val158met variant with antidepressant treatment response in major depression

In several previous biochemical, pharmacological, and genetic studies, the catechol-O-methyltransferase (COMT) has been suggested to be involved in the pathogenesis as well as the pharmacological treatment of affective disorders. In the present study, 256 patients with major depression (DSM-IV) of Caucasian descent were genotyped for the functional COMT val158met polymorphism and characterized for clinical response to antidepressive pharmacological treatment as measured by intra-individual changes of Hamilton Depression (HAM-D-21) scores over 6 weeks. The COMT 158val/val genotype conferred a significant risk of worse response after 4-6 weeks of antidepressant treatment in patients with major depression (week 4: p=0.003; week 5: p<0.0001; week 6: p<0.0001) after Bonferroni correction for multiple comparisons. The present results strongly point toward a negative influence of the higher activity COMT 158val/val genotype on antidepressant treatment response during the first 6 weeks of pharmacological treatment in major depression, possibly conferred by consecutively decreased dopamine availability. This finding suggests a potentially beneficial effect of an antidepressive add-on therapy with substances increasing dopamine availability individually tailored according to COMT val158met genotype.

No association of COMT Val158Met polymorphism with suicidal behavior or CSF monoamine metabolites in mood disorders

The Met allele of the Catechol-O-Methyltransferase (COMT) gene functional polymorphism (COMT-V158M) is associated with lower enzymatic activity than the Val allele and is reported to be associated with aggression, depression, and suicidal behavior. Since depression and impulsive-aggressive behavior may mediate risk for suicidal behavior, we assessed the association of this polymorphism with suicidal behavior. Clinical (impulsive aggression) and biological (CSF monoamine metabolites) endophenotypes were tested as potential mediators of the effect of genotype on suicide risk. Subjects with mood disorders (N = 486) and healthy volunteers (N = 119), all European Caucasian, were genotyped for COMT-V158M and assessed for DSM IV diagnoses, lifetime suicidal behavior, lifetime impulsivity, hostility, and aggression. CSF monoamine metabolites were assayed in a sub-sample of mood disorder patients (N = 111). We found no association between genotype and mood disorder diagnosis or with reported history of suicide attempt in mood disorder subjects. There was no association between genotype and lethality or method of suicide attempt, or with aggressive/impulsive traits. Further, there was no difference in monoamine metabolites by genotype. The COMT-V158M polymorphism was not associated with suicidal behavior in a Caucasian sample of mood disorder subjects, or with possible clinical or biological endophenotypes.

Socioeconomic status mediates the genetic contribution of the dopamine receptor D4 and serotonin transporter linked promoter region repeat polymorphisms to externalization in preadolescence

The impact of socioeconomic status (SES) and genetic polymorphisms on individual differences for externalized behaviors have often been investigated separately in studies of children and adults. In a general population sample of 607 Italian preadolescents, we examined the independent and joint effects of SES and the dopamine receptor D4 (DRD4) and serotonin transporter linked promoter region (5-HTTLPR) polymorphisms upon rule-breaking and aggressive behaviors measured with the Child Behavior CheckList/6–18. We found evidence, which was based on both one locus and two-loci genotype analyses, that low SES andDRD4long and5-HTTLPRlong alleles, both alone and in interaction, are associated with higher aggressive behavior scores. The effects were similar but more modest and limited to one locus genotype analyses for rule-breaking behavior. Consistent with studies that showed the effects of societal moderators on the heritability of externalized behaviors across different segments of the population, we suggest that diminished social constraints associated with low parental SES may act as enhancers of the genetic influence of specificDRD4and5-HTTLPRalleles over aggressive behaviors in preadolescence.

Relationship of catechol-O-methyltransferase to schizophrenia and its correlates: evidence for associations and complex interactions

Converging lines of evidence suggest that the gene that codes for catechol-O-methyltransferase (COMT) may play a role in the etiology, neurodevelopment, and expression of schizophrenia. Dopamine dysregulation has long been implicated in schizophrenia pathogenesis, and COMT appears to play a role in dopamine functioning, especially in prefrontal cortex. Additionally, the COMT gene maps to the commonly deleted region on chromosome 22q11 in 22q11 deletion syndrome (22q11DS), a disorder associated with a highly elevated risk for the development of psychosis. An amino acid polymorphism (Val158Met) in the COMT gene affects the activity level of COMT, which affects the levels of available catecholamines in the brain. Val158Met has been found to predict performance on dopamine-mediated prefrontal tasks in healthy adults and patients with schizophrenia. While association and linkage studies have failed to provide conclusive evidence of a strong link between COMT genotype and schizophrenia, evidence linking neural functioning and behavioral output has been somewhat more promising. The present work examines evidence for the role of COMT in schizophrenia pathogenesis, and associations between COMT and cognitive and behavioral correlates of schizophrenia and related disorders. Additionally, evidence for complex interactions involving COMT is examined, including the utility of haplotype analysis and evidence for gene-by-gene and gene-by-environment interactions.

Is there an association between T102C polymorphism of the serotonin receptor 2A gene and urinary incontinence?

The regulation of bladder function is influenced by central serotonergic modulation. Several genetic polymorphisms related to serotonin control have been described in the literature. T102C polymorphism of the serotonin receptor 2A gene (5-HT2A) has been shown to be associated with certain diseases such as non-fatal acute myocardial infarction, essential hypertension, and alcoholism. In the present study, we examined the association between 5-HT2A gene polymorphism and urinary incontinence in the elderly. A case-control study was performed in 298 elderly community dwellers enrolled in the Gravataí-GENESIS Project, Brazil, which studies gene-environmental interactions in aging and age-related diseases. Clinical, physical, biochemical, and molecular analyses were performed on volunteers. 5-HT2A genotyping was determined by PCR-RFLP techniques using the HpaII restriction enzyme. The subjects had a mean age of 68.05 +/- 6.35 years (60-100 years), with 16.9% males and 83.1% females. The C allele frequency was 0.494 and the T allele frequency was 0.506. The CC genotype frequency was 21.78%, the CT genotype frequency was 55.24% and the TT genotype frequency was 22.98%. We found an independent significant association between the TT genotype (35.7%) and urinary incontinence (OR = 2.06, 95%CI = 1.16-3.65). Additionally, urinary incontinence was associated with functional dependence and systolic hypertension. The results suggest a possible genetic influence on urinary incontinence involving the serotonergic pathway. Further investigations including urodynamic evaluation will be performed to better explain our findings.

Association study of seven polymorphisms in four serotonin receptor genes on suicide victims

A number of molecular genetic studies have investigated if serotonin (5-HT) receptor subtypes are involved in the pathogenesis of depression, suicidal behavior, aggression, and impulsive behavior. Existence of many receptor subtypes for a single transmitter permits a great diversity of signaling raising the possibility that they may serve as genetic markers for suicidal behavior. Most previous studies of suicide have analyzed polymorphisms of the receptors 5-HT1A, 5-HT1B, 5-HT2A, fewer have examined 5-HT1F. We report a study of possible association between the polymorphisms in the 5-HT receptor genes (1A, 1B, 1F, and 2A) and suicidal behavior on a sample of 226 suicide victims and 225 healthy control subjects. No significant differences in genotype frequency distributions between the suicide victims and healthy control subjects were observed for four polymorphisms; three were not polymorphic. A single polymorphism, C-1420T in gene 5-HT2A, showed a slight association with suicide (chi2= 4.94, df = 2, P = 0.067), but the correlation was not statistically significant. None of the tested genetic variants of serotonin receptors appears to be associated with suicidal behavior in the Slovenian population which has a relatively high suicide rate.

Temperament and character in mood disorders: influence of DRD4, SERTPR, TPH and MAO-A polymorphisms

Gene variants exert a complex range of effects on human normal and abnormal behavior. We previously reported the effect of gene variants in serotoninergic and dopaminergic pathways, in a range of clinical features in mood disorders, such as symptomathology, periodicity, social adjustment and treatment response. In this paper we hypothesized that the same gene variants could influence temperamental traits in mood disorders patients. We focused on genes of the serotoninergic and dopaminergic systems (dopamine receptor D4 gene, DRD4; serotonin transporter gene, promoter region SERTPR; tryptophan hydroxylase gene, TPH; monoamine oxidase A gene, MAO-A). Two hundred and seven euthymic subjects, affected by major depressive disorder (n=73) and bipolar disorder (n=134) were assessed by the Cloninger's Temperament and Character Inventory (TCI) and typed using PCR-based analyses. Possible stratification factors such as demographic, clinical and other temperamental factors were also taken into account. We observed that homozygosity for the short SERTPR allele was associated with low novelty-seeking scores (p=0.006) and genotypes containing the DRD4 long allele were marginally associated with low harm avoidance (p=0.05). Finally, the long MAO-A allele was associated with decreased persistence scores among females (p=0.006). Our observation of a pattern of influence on temperamental dimension exerted by serotonergic and dopaminergic genes suggests that the contribution of these polymorphisms to the clinical presentation of mood disorders could be mediated by an influence on personality differences.

The Italian preadolescent mental health project (PrISMA): rationale and methods

The Italian preadolescent mental health project (PrISMA--Progetto Italiano Salute Mentale Adolescenti) is the first Italian study designed to estimate the prevalence of mental disorders in preadolescents (10-14 years old) living in urban areas, and to analyse the demographic and biological correlates of emotional and behavioural problems. This paper describes the rationale, methods and the analysis plan of the project. The design of the study used a two-stage sampling procedure, one screening stage of emotional and behavioural problems in a large sample of subjects attending public and private schools and a second stage of diagnostic assessment in a sample including all high scorers and a proportion of low scorers. In the screening stage, parents of preadolescents were asked to fill in the Child Behavior Checklist (CBCL), whereas in the second stage preadolescents and their parents were administered the Development and Well Being Assessment for the assessment of mental disorders together with the Strengths and Difficulties Questionnaire and two scales (C-GAS and HoNOSCA) designed to evaluate the functioning of the preadolescent in different areas. Genetic samples were collected during the screening stage, after parents gave their informed written consent. The findings of this study are expected to allow an adequate planning of interventions for the prevention and the treatment of mental disorders in preadolescence as well as efficient health services.

Association between COMT (Val158Met) functional polymorphism and early onset in patients with major depressive disorder in a European multicenter genetic association study

The available data from preclinical and pharmacological studies on the role of the C-O-methyl transferase (COMT) support the hypothesis that abnormal catecholamine transmission has been implicated in the pathogenesis of mood disorders (MD). We examined the relationship of a common functional polymorphism (Val108/158Met) in the COMT gene, which accounts for four-fold variation in enzyme activity, with 'early-onset' (EO) forms (less than or equal to 25 years) of MD, including patients with major depressive disorder (EO-MDD) and bipolar patients (EO-BPD), in a European multicenter case-control sample. Our sample includes 378 MDD (120 EO-MDD), 506 BPD (222 EO-BPD) and 628 controls. An association was found between the high-activity COMT Val allele, particularly the COMT Val/Val genotype and EO-MDD. These findings suggest that the COMT Val/Val genotype may be involved in EO-MDD or may be in linkage disequilibrium with a different causative polymorphism in the vicinity. The COMT gene may have complex and pleiotropic effects on susceptibility and symptomatology of neuropsychiatric disorders.

The dopamine D4 receptor gene 48-base-pair-repeat polymorphism and mood disorders: a meta-analysis

BACKGROUND

We conducted a meta-analysis to re-evaluate the role of the dopamine D4 receptor gene 48-base-pair- repeat (DRD4) polymorphism in mood disorders.

METHODS

DRD4 allele frequencies were compared between 917 patients with unipolar (UP) or bipolar affective disorder (BP) and 1164 control subjects from 12 samples, using the Cochrane Review Manager.

RESULTS

An association was found between all mood disorder groups and DRD4.2. After correcting for multiple testing, the association between DRD4.2 and BP dropped to insignificance; however, the evidence of an association between the DRD4.2 allele and UP (p < .001) and the combined group (p < .001) remained. There was no evidence for heterogeneity or publication bias.

CONCLUSIONS

These findings suggest that the DRD4.2 allele is a risk allele for depression symptomatology. Meta-analysis may be a valuable objective tool for a quantitative summary of evidence for association studies in psychiatric genetics.

Hardy–Weinberg equilibrium in genetic association studies: an empirical evaluation of reporting, deviations, and power

We evaluated the testing and reporting of Hardy-Weinberg equilibrium (HWE) in recent genetic association studies, detected how frequently HWE was violated and estimated the power for HWE testing in this literature. Genetic association studies published in 2002 in Nature Genetics, American Journal of Human Genetics, and American Journal of Medical Genetics were assessed. Data were analyzed on 239 biallelic associations using 154 distinct genotype distribution data sets where HWE could be tested. Any information on HWE was given only for 150 (62.8%) associations (92 (59.7%) data sets). Reanalysis of the data showed significant deviation from HWE in the disease-free controls of 20 associations (13 data sets), but only four of them (two data sets) were admitted in the published articles. Another four deviations (in two data sets) were observed in the combined sample of cases and controls of studies where both cases and controls were diseased, and none were reported in the papers. In all six tested multiallelic associations (six data sets), there was violation of HWE, but this was not admitted in the published articles. Power calculations showed that most studies conforming to HWE simply were largely underpowered to detect HWE deviation; for example, power to detect an inbreeding of magnitude F=0.10 exceeded 80% in only 11 (7%) of the data sets being tested. This empirical evidence suggests that, even in high profile genetics journals, testing and reporting for HWE is often neglected and deviations are rarely admitted in the published reports. Moreover, power is limited for HWE testing in most current genetic association studies.

Monoamine Oxidase A and Tryptophan Hydroxylase Gene Polymorphisms

Most of the candidate gene studies in bipolar disorder have focused on the major neurotransmitter systems that are influenced by drugs used in the treatment of this disorder. The monoamine oxidase A (MAOA) and the tryptophan hydroxylase (TPH1, TPH2) genes are two of the candidates that have been tested in a series of association studies using unrelated or family-based controls. This review summarizes the existing association studies regarding these genes. Most of these studies were based on the unrelated case-control design with samples of 50 to 600 subjects. Regarding MAOA, three meta-analyses with partially overlapping samples supported a modest effect of this gene in bipolar disorder in female Caucasians. However, as several studies could not replicate these findings, more work is necessary to demonstrate unequivocally the involvement of MAOA in bipolar disorder and establish the biological mechanism underlying the genetic association. With respect to TPH1 and TPH2, the majority of studies did not provide evidence for an association between these genes and bipolar disorder. The genes are more likely to be related to suicidal behavior than to bipolar disorder.