Sexually dimorphic relationship of a 5-HT2A promoter polymorphism with obsessive-compulsive disorder

Fish consumption and depression in Korean population: The Korea National Health and Nutrition Examination Survey, 2013-2021

BACKGROUND

Epidemiological studies in some populations showed that dietary intake of fish may be inversely associated with depression, but large studies in Korean population are limited. Thus, we investigated the association between fish consumption and depression, considering the serving size of fish, in Korean adults.

METHODS

This study was based on the data from the Korea National Health and Nutrition Examination Survey (2013-2021), which is a large nationally representative study of Korean population. Fish consumption was assessed with a 24-hour dietary recall, and physician-diagnosed depression status was assessed using questionnaires from the health interview survey. Multivariable logistic regression models adjusting for demographic, lifestyle, and dietary factors were used to calculate odds ratios (OR) and 95 % confidence intervals (CI) for depression.

RESULTS

A total of 31,632 adults aged 19-64 years were included in the analysis. After adjusting for covariates, highest fish consumption (≥4 servings/week) was significantly associated with 26 % lower odds of depression compared to the lowest fish consumption (<1 servings/week) (OR 0.74; 95 % CI, 0.60-0.92, P for trend = 0.007). A similar inverse association was found in female adults (OR 0.76; 95 % CI, 0.59-0.97, P for trend = 0.018), but no significant association was found in male adults (OR 0.75; 95 % CI, 0.49-1.15, P for trend = 0.223).

LIMITATIONS

Since KNHANES is a cross-sectional study, it is difficult to evaluate the causal relationship between fish consumption and depression risk.

CONCLUSIONS

This study results suggest that high fish consumption is associated with lower risk of depression in Korean adults, especially in female adults.

Obsessive-Compulsive Disorder Interactome Profile Analysis: A Perspective From Molecular Mechanism

Introduction:

Obsessive-Compulsive Disorder (OCD) is one of the complex neuropsychiatric conditions. This disorder disables individuals in many different aspects of their personal and social life. Interactome analysis may provide a better understanding of this disorder’s molecular origin and its underlying mechanisms.

Methods:

In this study, the OCD-associated genes were extracted from the literature. The criterion for gene selection was to choose genes with at least one significant report. Furthermore, by applying Cytoscape and its plugins, protein-protein interaction network, and gene ontology of the 31 candidate genes related to OCD from genetic association studies is examined. The cross-validation method was used for network centrality assessment.

Results:

A scale-free network, including 1940 nodes and 3269 edges for 31 genes, was constructed. According to the network centrality evaluation, ESR1, TNFα, DRD2, DRD4, HTR1B, HTR2A, and CDH2 showed the highest values and can be considered hub-bottlenecks elements. It is also confirmed by the number of 123 cross-validation tests that the frequency of these essential genes remains unaltered against the initial seed genes’ changes with the accuracy of 0.962. Besides, enrichment analysis identified four highlighted biological processes related to the 31 candidate genes. The top biological processes are determined as dopamine transport, learning, memory, and monoamine transport.

Conclusion:

Among 31 initial genes, 7 were introduced as crucial elements for onset and development in OCD and can be suggested for further investigations. Furthermore, the complex molecular origin of OCD requires high-throughput screening for diagnosis and treatment goals. The findings are a possible valuable source to establish molecular-based diagnostic tools for OCD.

The association of HTR2A polymorphisms with obsessive-compulsive disorder and its subtypes: A meta-analysis

BACKGROUND

Genetic risk factors that contribute to obsessive-compulsive disorder (OCD) have yet to be elucidated. Historically, serotonergic dysfunction has been implicated. Evidence from the literature points towards the serotonin receptor 2A gene (HTR2A) as a primary candidate. Our meta-analysis investigated whether polymorphisms in HTR2A are associated with OCD or its subtypes, based on sex and age of onset.

METHODS

Studies employing case-control or family-based designs were systematically searched, and those meeting eligibility underwent quality assessment, resulting in 18 studies. A random-effects meta-analysis using standard inverse-variance weighting to compute odds ratio (OR) was conducted. To examine sensitivity, results were also obtained using a more conservative statistical method.

RESULTS

Three HTR2A variants were identified: T102C, G-1438A, and C516T. T102C and G-1438A were analyzed together due to strong linkage disequilibrium, where the 102T allele co-occurs with -1438A allele. Results reported as OR [95%CI] showed that the T/A allele were significantly associated with OCD, 1.14 [1.01, 1.29]. After stratification, results remained significant for females, 1.20 [1.00, 1.45], and early-onset OCD, 1.27 [1.02, 1.58], but not males, 1.06 [0.91, 1.23]. No associations were found for late-onset OCD, 0.98 [0.70, 1.37], or C516T, 1.22 [0.14, 10.37], but conclusions cannot be drawn from two studies.

LIMITATIONS

Associations no longer reached significance with the conservative statistical approach. HTR2A alone cannot explain OCD complexity and limited samples reporting genetic data according to subtypes.

CONCLUSIONS

These results suggest a possible association of HTR2A polymorphisms with OCD, but further investigations considering sex and age of onset with larger samples is needed.

Association study of the PDE4D gene and obsessive-compulsive disorder in a Chinese Han population

OBJECTIVE

Multiple evidence suggests an involvement of the PDE4D in mental disorders. Therefore we investigate the association between obsessive-compulsive disorder and a polymorphism of the single nucleotide polymorphisms of PDE4D gene in the Chinese Han population.

METHODS

We genotyped and performed a case-control association analysis of the PDE4D polymorphism rs1838733 in 400 obsessive-compulsive disorder patients and 459 healthy control subjects.

RESULTS

The site conformed to Hardy-Weinberg (P > 0.05), three genotypes (AA, AG, GG) of PDE4D gene rs1838733 were detected. We demonstrated three principal results. First, there were no significant differences between the case and health controls in the genotype and allele at rs1838733 (P > 0.05). Second, there were no significant differences in the allele and genotype frequency between different genders obsessive-compulsive disorder (P > 0.05). Third, the genotype of single nucleotide polymorphism rs1838733 was associated with late-onset obsessive-compulsive disorder and female late-onset obsessive-compulsive disorder (P < 0.05).

CONCLUSION

The present study is the first to verify the associations of single nucleotide polymorphisms rs1838733 of the PDE4D gene with obsessive-compulsive disorder in a Chinese Han population. We found the genotype of single nucleotide polymorphism rs1838733 was associated with the occurrence of late-onset obsessive-compulsive disorder and female late-onset obsessive-compulsive disorder. Therefore, PDE4D may play a role in the pathogenesis of obsessive-compulsive disorder and may become a potential target for obsessive-compulsive disorder treatment in future research. Further studies should verify the current findings.

Genetic variability in the serotoninergic system and age of onset in anorexia nervosa and obsessive-compulsive disorder

The age of onset of some psychiatric disorders may have etiopathogenic and clinical effects and may influence outcome. Following on from previous work by our group where we showed that early onset anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) shared a common genetic background, the aim of the present study is to assess genetic pleiotropy related to the serotonergic system (SLC6A4, 5HTR2A, 5HTR2C, TPH2, SLC18A1), in a common phenotype such as very-early age of onset. One hundred and sixteen adolescents diagnosed with AN and 74 adolescents diagnosed with OCD participated in the present study. We confirmed the existence of a genetic overlap between OCD and AN. Specifically, we described genetic pleiotropy for age at onset across these disorders, associating two SNPs (rs6311, rs4942587) of the HTR2A with the very-early onset phenotype.

Haplotypic and Genotypic Association of Catechol-O-Methyltransferase rs4680 and rs4818 Polymorphisms and Treatment Resistance in Schizophrenia

Treatment-resistant schizophrenia (TRS) continues to be a challenge. It was related to different factors, including alterations in the activity of brain dopaminergic system, which could be influenced by the dopamine-degrading enzyme, catechol-O-methyltransferase (COMT). Variants of the COMT gene have been extensively studied as risk factors for schizophrenia; however, their association with TRS has been poorly investigated. The aim of the present study was to determine the haplotypic and genotypic association of COMT rs4680 and rs4818 polymorphisms with the presence of TRS. Overall, 931 Caucasian patients diagnosed with schizophrenia (386 females and 545 males) were included, while 270 participants met the criteria for TRS. In males, no significant haplotypic and genotypic associations between COMT rs4680 and rs4818 polymorphisms and TRS were detected. However, genotypic analyses demonstrated higher frequency of COMT rs4680 AA genotype carriers compared to G-allele carriers (p = 0.033) and higher frequency of COMT rs4818 CC genotype carriers than G-allele carriers (p = 0.014) in females with TRS. Haplotype analyses confirmed that the presence of the G allele in females was associated with lower risk of TRS. In women with TRS, the high activity G-G/G-G haplotype was rare, while carriers of other haplotypes were overrepresented (p = 0.009). Such associations of COMT rs4680 and rs4818 high-activity (G variants), as well as G-G/G-G haplotype, with the lower risk of TRS in females, but not in males, suggest significant, but sex-specific influence of COMT variants on the development of treatment-resistance in patients with schizophrenia. However, due to relatively low number of females, those findings require replication in a larger sample.

Association analysis of SLC6A4 and HTR2A genes with obsessive-compulsive disorder: Influence of the STin2 polymorphism

BACKGROUND

Obsessive-Compulsive Disorder (OCD) is a complex and chronic disorder characterized by recurrent thoughts and/or repetitive behaviors. Given the potent anti-obsessional effects of the so-called serotonin reuptake inhibitors, genes related to serotonergic system may be well implicated in the etiopathogenesis of OCD. The gene encoding the serotonin transporter (SLC6A4), which shows a variable number of tandem repeat (VNTR) polymorphism in intron 2 (STin2), have been previously associated with OCD. Additionally, the serotonin 2A receptor gene (HTR2A) has two polymorphisms (A-1438G - rs6311, and T102C - rs6313), which have also been overrepresented among OCD patients. Therefore, the aim of this study is to evaluate the association of these three polymorphisms with OCD, through the examination of potential sources of heterogeneity in previous studies including age of onset, sex and symptom dimensions.

METHODS

Polymorphisms were genotyped by Polymerase Chain Reaction (PCR) in a sample of 203 OCD patients and 205 healthy controls from Brazil.

RESULTS

Although we did not observe any statistically significant association between the HTR2A gene polymorphisms and OCD or its clinical features, SLC6A4 STin2 polymorphism was significantly more common among OCD patients as compared to health controls. Further, a significant association between the STin2.12 allele and OCD, as well as a dominant effect of the STin2.12 allele in OCD was seen. Of note, late-onset (>18years) OCD was significantly more often seen in association with homozygosis for STin2.12 allele. No significant associations were observed with different OCD symptom dimensions.

CONCLUSION

Our results indicate an important influence of the STin2 polymorphism in OCD, but more studies are warranted to confirm these results.

Association of serotonin receptor 2a haplotypes with obsessive-compulsive disorder and its treatment response in Iranian patients: a genetic and pharmacogenetic study

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder causing intrusive thoughts or repetitive behaviors. Serotonin reuptake inhibitors are used for OCD treatment, but 40%-60% of patients do not respond to them adequately. In this study, the associations of serotonin receptor 2a polymorphisms rs6311 and rs6313 with OCD, its familial form and fluvoxamine treatment response in Iranian population were investigated.

PATIENTS AND METHODS

Association analyses were conducted in 293 OCD cases fulfilling the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV-TR and 245 controls. Pharmacotherapy was defined as 12 weeks of treatment with fluvoxamine (150-300 mg). Treatment response was considered as >25% reduction in Yale-Brown Obsessive Compulsive Scale score. Genotyping was performed by means of PCR-RFLP.

RESULTS

The results showed no association of rs6311 or rs6313 with OCD, but their haplotypes had different distribution patterns in cases and controls. Moreover, rs6313 was associated with the familial form of OCD in females significantly (P=0.005) under the recessive genetic model. Moreover, rs6311-rs6313 haplotypes were associated with fluvoxamine treatment response in OCD patients with more AC and less AT in responders.

CONCLUSION

HTR2A haplotypes are associated with OCD and its treatment response with a fluvoxamine in Iranian patients. Furthermore, the observed association of rs6313 with the familial form of OCD in females suggests different genetic background of OCD familial and non-familial forms, which needs further investigation.

A review of the role of serotonin system genes in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder that causes the patient to experience intrusive thoughts and/or to carry out repetitive, ritualized behaviors that are time consuming and impairing. OCD is familial and heritable. The genetic factors responsible for pathogenesis, however, remain largely unknown despite the numerous candidate gene studies conducted. Based on efficacy of serotonin reuptake inhibitors (SRIs) in treating OCD, serotonin system genes have been a dominant focus in OCD candidate gene studies. We review the most commonly studied candidate serotonin system gene variants (specifically in SLC6A4, HTR2A, HTR1B, and HTR2C) and their association with OCD. Although findings to date are mixed, serotonin transporter polymorphism 5-HTTLPR and HTR2A polymorphism rs6311 (or rs6313) are most consistently associated with OCD. Mixed findings may be the result of genetic complexity and phenotypic heterogeneity that future studies should account for. Homogenous patient subgroups reflecting OCD symptom dimensions, OCD subtypes, and sex should be used for gene discovery.

The need for inclusion of sex and age of onset variables in genetic association studies of obsessive-compulsive disorder: Overview

Obsessive-compulsive disorder (OCD) is a heterogeneous mental disorder that significantly impairs an individual's functioning. The candidate gene approach has proven to be a useful tool in investigating potential risk genes for OCD, but genetic studies have been largely inconclusive. Etiologically distinct forms of obsessive-compulsive disorder based on sex and age of onset have been identified, yet many genetic studies fail to examine the association by these subtypes. Due to the sexually dimorphic nature of the disorder, positive associations have been found with OCD in males only, suggesting the potential for identifying risk genes that contribute to OCD in women, such as perinatal OCD. This review includes a brief overview of the disorder and its subtypes, with a current update on candidate genes that may contribute to OCD using single nucleotide polymorphisms (SNPs) and genome wide association studies (GWAS).

An association study between DLGAP1 rs11081062 and EFNA5 rs26728 polymorphisms with obsessive-compulsive disorder in a Chinese Han population

BACKGROUND

A recent genome-wide association study indicated that the single nucleotide polymorphisms (SNPs) rs11081062 in DLGAP1 and rs26728 in EFNA5 were associated with obsessive-compulsive disorder (OCD) in Caucasians. The present case-control association study assessed the global relevance of these two SNPs with respect to OCD subtypes in a Chinese Han population.

METHODS

We recruited 320 OCD patients and 431 age- and sex-matched controls from a Chinese Han population. rs11081062 and rs26728 SNPs were genotyped by real-time TaqMan polymerase chain reaction, and the chi-squared test was used to compare allele and genotype frequencies of variants between the two groups.

RESULTS

No significant differences were found in allele or genotype frequencies of DLGAP1 rs11081062 and EFNA5 rs26728 between the OCD and control groups. Moreover, consistently negative results were observed when classifying by sex, onset age, and comorbidity. However, on analyzing OCD subphenotypes, significant associations were observed between rs11081062 and the presence of contamination obsessions and cleaning compulsions (χ (2)=7.724, P=0.021 by genotype; χ (2)=3.745, P=0.053 by allele; and χ (2)=0.821, P=0.365 by genotype, χ (2)=27.809, P=0.000 by allele, respectively), and rs26728 with the presence of repeating compulsions (χ (2)=8.285, P=0.004 by genotype; χ (2)=7.512, P=0.006 by allele).

CONCLUSION

Although we found no association between DLGAP1 rs11081062 and EFNA5 rs26728 SNPs with OCD in a Chinese Han population, obvious associations were observed with OCD subphenotypes. Therefore, it appears to be useful to divide OCD into more homogeneous subphenotypes to help understand the complex genetic basis of this disorder. Further investigations are needed to replicate these findings using larger sample sizes, different populations, and other polymorphisms.

Genetics of obsessive–compulsive disorder: a research update

The genetic study of obsessive-compulsive disorder (OCD) has made significant gains in the past decade. However, etiological gene findings are still elusive. Epidemiological studies, including family and twin studies, strongly support a genetic component for OCD. In addition, complex segregation analyses suggest the presence of at least one major gene. The neurobiology of OCD also lends support to the notion that programmed CNS-based biological processes underlie OCD symptom expression, with mapping of brain circuits to fronto-subcortical circuits in a consistent manner. Genetic linkage studies of OCD, using families with multiple affected relatives, have generated several suggestive linkage peaks, regions that may harbor a gene or genes for OCD. However, the presence of multiple linkage peaks has added to the complexity of OCD genetics, suggesting that the exploration of gene-gene interactions and gene-environment interactions, in addition to the exploration of alternate phenotypes based on symptom expression, age at onset or comorbid conditions, may be key in locating etiologic genes. Finally, candidate gene studies, while promising, are not yet associated with linkage regions, except in the case of the glutamate transporter gene SLC1A1 in 9p24. While OCD appears to have a genetic component, additional innovative research is needed to unravel the genetic influences in the disorder.

Molecular genetics of obsessive-compulsive disorder: a comprehensive meta-analysis of genetic association studies

Twin studies indicate that obsessive-compulsive disorder (OCD) is strongly influenced by additive genetic factors. Yet, molecular genetic association studies have yielded inconsistent results, possibly because of differences across studies in statistical power. Meta-analysis can yield greater power. This study reports the first comprehensive meta-analysis of the relationship between OCD and all previously examined polymorphisms for which there was sufficient information in the source studies to compute odds ratios (ORs). A total of 230 polymorphisms from 113 genetic association studies were identified. A full meta-analysis was conducted for 20 polymorphisms that were examined in 5 or more data sets, and a secondary meta-analysis (limited to the computation of mean effect sizes) was conducted for 210 polymorphisms that were examined in fewer than 5 data sets. In the main meta-analysis, OCD was associated with serotonin-related polymorphisms (5-HTTLPR and HTR2A) and, in males only, with polymorphisms involved in catecholamine modulation (COMT and MAOA). Nonsignificant trends were identified for two dopamine-related polymorphisms (DAT1 and DRD3) and a glutamate-related polymorphism (rs3087879). The secondary meta-analysis identified another 18 polymorphisms with significant ORs that merit further investigation. This study demonstrates that OCD is associated with multiple genes, with most having a modest association with OCD. This suggests a polygenic model of OCD, consistent with twin studies, in which multiple genes make small, incremental contributions to the risk of developing the disorder. Future studies, with sufficient power to detect small effects, are needed to investigate the genetic basis of OCD subtypes, such as early vs late onset OCD.

The interaction between Comt and Bdnf variants influences obsessive-compulsive-related dysfunctional beliefs

Cognitive models emphasize the importance of dysfunctional beliefs as overimportance/need to control thoughts, perfectionism, intolerance of uncertainty, responsibility, and overestimation of threat in obsessive-compulsive disorder (OCD). Twin studies suggest that these beliefs are significantly heritable, but candidate genes associated with them have not been analyzed. We genotyped the Val158Met in the COMT gene and Val66Met variant in the BDNF gene in 141 OCD patients and analyzed their single and interactive effects on the obsessive beliefs questionnaire (OBQ-44). Variability in dysfunctional beliefs was not affected by the COMT or BDNF genotype in isolation, but we detected a significant COMT×BDNF interaction effect on responsibility/overestimation of threat and overimportance/need to control thoughts scores. Subjects with the BDNF Met-present and the COMT Met-present genotype showed higher scores on responsibility/overestimation of threat. An interaction between dopaminergic and neurotrophic functional gene variants may influence dysfunctional beliefs hypothesized to contribute to the development of OCD.

Gender differences in obsessive-compulsive disorder: a literature review

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a heterogeneous condition, in which subtypes have been proposed. Previous studies suggested that gender plays a relevant role in OCD phenotypic expression. This study aimed to review the literature on gender differences in clinical, genetic or familial aspects of OCD.

METHOD

A conventional review was conducted, including all papers that investigated demographic, clinical, and genetic aspects of OCD according to gender. The search was based on data available in Medline and PsycINFO databases in the last 20 years, using as keywords: obsessive-compulsive disorder; and: gender, sex, male, female, demographic characteristics, clinical features, clinical characteristics, genetic, genes, genetics gender OCD, genes OCD, genes OCD males, genes OCD females.

RESULTS

Sixty three of 487 phenotypical and genetics studies were selected. Most studies indicate that male patients are more likely than females to be single, present early onset of symptoms and chronic course of the disorder, greater social impairment, more sexual-religious and aggressive symptoms, and greater comorbidity with tic and substance use disorders. Female patients present more contamination/cleaning symptoms and greater comorbidity with eating and impulse-control disorders. Genetic and family studies are inconclusive, but suggest that gender may play a role in the disease expression.

CONCLUSIONS

Gender is a relevant factor that should be taken into account when evaluating OCD patients. More studies are necessary to determine whether in fact it defines a homogeneous and particular group in OCD.

5-HT2A receptor -1438 G/A polymorphism and serotonergic antidepressant-induced sexual dysfunction in male patients with major depressive disorder: a prospective exploratory study

INTRODUCTION

To date, few studies have specifically investigated the genetic determinants of antidepressant-induced sexual dysfunction (SD).

AIM

The aim of this prospective study was to examine whether the 5-HT2A receptor -1438 G/A polymorphism has functional consequences on sexual well-being in young adult men presenting with their first episode of major depressive disorder (MDD) after serotonergic antidepressant treatment.

METHODS

Between May 2010 and June 2011, a total of 56 drug-naïve patients presenting with their first episode of MDD were recruited from a psychiatric hospital and received either a selective serotonin reuptake inhibitor or venlafaxine monotherapy; the patients were then genotyped. Over the course of antidepressant treatment, the population was divided into a SD group (N=16) and a non-SD group (N=29) based on the Arizona Sexual Experience Scale (ASEX). Participants who did not achieve a significant improvement, as assessed by the Hamilton Depression Rating Scale (HAMD-17), were excluded from the final data analysis.

MAIN OUTCOME MEASURES

The primary outcome measures were the differences in the genotype distribution and allele frequencies between groups.

RESULTS

In the SD group, the AA genotype was significantly overrepresented (P=0.004), and the mean baseline HAMD-17 score, the mean baseline ASEX score, and the mean end-point ASEX score were significantly higher than those in the non-SD group (P=0.026, P=0.004, and P<0.001, respectively). The mean end-point HAMD-17 score (P=0.115) did not differ significantly between the two groups.

CONCLUSION

These results suggest that the AA genotype may be a genetic trait offering an opportunity to strengthen early detection of serotonergic antidepressant-induced SD in young adult male patients with MDD, whereas the G allele is protective against SD in this population.

Sex Differences in Genetic and Environmental Influences on Obsessive–Compulsive Symptoms in South Korean Adolescent and Young Adult Twins

Recent molecular genetic studies provide suggestive evidence for sexual dimorphism in genetics of obsessive-compulsive disorder. However, only a few twin studies have addressed the question of sex differences in genetic and environmental contributions to variation of obsessive–compulsive symptoms. The aim of the present study was to estimate genetic and environmental influences on obsessive–compulsive symptoms in South Korean twins, with a special emphasis on sex difference. In total, 751 adolescent and young adult twin pairs (ages: 13–23 years) completed a Korean version of the 30 items of the Maudsley Obsessional — Compulsive Inventory (MOCI) through a mail survey. A sum of the answers for the 30 items was calculated to represent a total score for obsessive–compulsive symptoms (hereafter, the MOCIT). Males had significantly higher variance of the MOCIT than did females. In males, monozygotic (MZ) twin correlation was significantly higher than dizygotic (DZ) twin correlations (.56 vs. .24), whereas in females, MZ and DZ twin correlations were not significantly different from each other (.39 vs. .36). The general sex-limitation model was applied to the twin data. The results of model-fitting analyses indicated that the unstandardized genetic variance as well as heritability estimate (53% vs. 41%) for the MOCIT was higher in males than in females. However, shared environmental influences did not attain statistical significance perhaps due to insufficient statistical power.

Pilot study on HTR2A promoter polymorphism, -1438G/A (rs6311) and a nearby copy number variation showed association with onset and severity in early onset obsessive-compulsive disorder

A previous study showed that a single nucleotide polymorphism (SNP), -1438G/A (rs6311), found in the transcriptional control region of the gene that encodes the serotonin-receptor 2A (HTR2A) was associated with obsessive-compulsive disorder (OCD) in a sample of children and adolescents. In this study, we reanalyzed the association of this SNP with OCD in an enlarged population of 136 cases (55 previous + 81 new cases) and compared them to 106 newly recruited, healthy, age-matched controls. We also investigated whether this SNP or its copy number variations (CNV) was associated with OCD severity and age of onset. The CNV was analyzed in a DNA region located near rs6311. The results confirmed the association between the A-allele and early onset OCD in children and adolescents, with an odds ratio (OR) of 1.69 [95% CI (1.17, 2.46); p = 0.005]. Strikingly, we found that carriers of one copy (deletion) of the CNV were associated with a very early onset OCD (2.5 years earlier than the typical onset), and they had increased CY-BOCS scores (8.7 points higher compared to "normal" CNV and duplications); which is related to increased severity of OCD symptoms (p = 0.031; p = 0.004, respectively). Compared to the normal CNV and duplications, the association between the deletion and OCD showed an OR of 7.56 [95% CI (1.32, 142.84); p = 0.020]. These results pointed to the functional importance of this promoter region of HTR2A; it influenced the occurrence, the onset, and the severity of OCD.

Association analysis of serotonin and catecholamine system candidate genes in obsessive-compulsive disorder in the Chinese population

Serotonin and catecholamine system studies provide increasing evidence for the importance of genetic factors in obsessive-compulsive disorder (OCD); we found that genetic linkage disequilibrium with OCD existed in the 5-HT2A-receptor promoter polymorphism -1438G/A. The results of our research strongly suggested that the -1438G/A promoter polymorphism plays a role in the psychopathology of OCD.

Long chain n-3 fatty acids intake, fish consumption and suicide in a cohort of Japanese men and women--the Japan Public Health Center-based (JPHC) prospective study

OBJECTIVE

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been implicated as protective against suicide. However, it is uncertain whether a higher intake of EPA and DHA or of fish, a major source of these nutrients, lowers suicidal risk among Japanese, whose fish consumption and suicide rate are both high. This study prospectively examined the relation between fish, EPA, or DHA intake and suicide among Japanese men and women.

METHOD

Subjects were 47,351 men and 54,156 women aged 40-69 years who participated in the JPHC Study, completed a food frequency questionnaire in 1995-1999, and were followed for death through December 2005. We used the Cox proportional hazards regression model to estimate the hazard ratio (HR) and 95% confidence interval (CI) for suicide by quintile of intake.

RESULTS

A total of 213 and 85 deaths from suicide were recorded during 403,019 and 473,351 person-years of follow-up for men and women, respectively. Higher intakes of fish, EPA, or DHA were not associated with a lower risk of suicide. Multivariate HRs (95% CI) of suicide death for the highest versus lowest quintile of fish consumption were 0.95 (0.60-1.49) and 1.20 (0.58-2.47) for men and women, respectively. A significantly increased risk of suicidal death was observed among women with very low intake of fish, with HRs (95% CI) for those in 0-5th percentile versus middle quintile of 3.41 (1.36-8.51).

CONCLUSIONS

Our overall result does not support a protective role of higher intake of fish, EPA, or DHA against suicide in Japanese men and women.

Association of SLC6A4 variants with obsessive-compulsive disorder in a large multicenter US family study

Genetic association studies of SLC6A4 (SERT) and obsessive-compulsive disorder (OCD) have been equivocal. We genotyped 1241 individuals in 278 pedigrees from the OCD Collaborative Genetics Study for 13 single-nucleotide polymorphisms, for the linked polymorphic region (LPR) indel with molecular haplotypes at rs25531, for VNTR polymorphisms in introns 2 and 7 and for a 381-bp deletion 3' to the LPR. We analyzed using the Family-Based Association Test (FBAT) under additive, dominant, recessive and genotypic models, using both OCD and sex-stratified OCD as phenotypes. Two-point FBAT analysis detected association between Int2 (P = 0.0089) and Int7 (P = 0.0187) (genotypic model). Sex-stratified two-point analysis showed strong association in females with Int2 (P<0.0002), significant after correction for linkage disequilibrium, and multiple marker and model testing (P(Adj) = 0.0069). The SLC6A4 gene is composed of two haplotype blocks (our data and the HapMap); FBAT whole-marker analysis conducted using this structure was not significant. Several noteworthy nonsignificant results have emerged. Unlike Hu et al., we found no evidence for overtransmission of the LPR L(A) allele (genotype relative risk = 1.11, 95% confidence interval: 0.77-1.60); however, rare individual haplotypes containing L(A) with P<0.05 were observed. Similarly, three individuals (two with OCD/OCPD) carried the rare I425V SLC6A4 variant, but none of them passed it on to their six OCD-affected offspring, suggesting that it is unlikely to be solely responsible for the 'OCD plus syndrome', as reported by Ozaki et al. In conclusion, we found evidence of genetic association at the SLC6A4 locus with OCD. A noteworthy lack of association at the LPR, LPR-rs25531 and rare 425V variants suggests that hypotheses about OCD risk need revision to accommodate these new findings, including a possible gender effect.

Multiple anxiogenic drugs recruit a parvalbumin-containing subpopulation of GABAergic interneurons in the basolateral amygdala

The basolateral amygdala is a nodal structure within a distributed and interconnected network that regulates anxiety states and anxiety-related behavior. Administration of multiple anxiogenic drugs increases cellular responses (i.e., increases c-Fos expression) in a subregion of the basolateral amygdala, but the neurochemical phenotypes of these cells are not known. The basolateral amygdala contains glutamatergic projection neurons and several populations of γ-aminobutyric acid-synthesizing (GABAergic) interneurons, including a population of parvalbumin (PV)-expressing GABAergic interneurons that co-express the excitatory 5-HT(2A) receptor. The role for these PV-expressing GABAergic interneurons in anxiety-states is unclear. In this experiment we examined the effects of multiple anxiogenic drugs including the 5-HT(2C/2A) receptor agonist m-chlorophenyl piperazine (mCPP), the adenosine receptor antagonist caffeine, the α(2)-adrenoreceptor antagonist yohimbine and the partial inverse agonist at the benzodiazepine allosteric site on the GABA(A) receptor, N-methyl-beta-carboline-3-carboxamide (FG-7142), on c-Fos expression in PV-immunoreactive (PV-ir) interneurons in subdivisions of the basolateral amygdala. All drugs with the exception of mCPP increased c-Fos expression in PV-ir neurons in the basolateral amygdaloid nucleus, anterior part (BLA). The numbers of c-Fos-immunoreactive (c-Fos-ir)/PV-ir GABAergic interneurons in the BLA were positively correlated with the numbers of c-Fos-ir serotonergic neurons in the mid-rostrocaudal dorsal raphe nucleus (DR) and with a measure of anxiety-related behavior. All four drugs increased c-Fos expression in non-PV-ir cells in most of the subdivisions of the basolateral amygdala that were sampled, compared with vehicle-injected controls. Together, these data suggest that the PV/5-HT(2A) receptor expressing GABAergic interneurons in the basolateral amygdala are part of a DR-basolateral amygdala neuronal circuit modulating anxiety-states and anxiety-related behavior.

Brain activation during cognitive planning in twins discordant or concordant for obsessive-compulsive symptoms

Neuroimaging studies have indicated abnormalities in cortico-striatal-thalamo-cortical circuits in patients with obsessive–compulsive disorder compared with controls. However, there are inconsistencies between studies regarding the exact set of brain structures involved and the direction of anatomical and functional changes. These inconsistencies may reflect the differential impact of environmental and genetic risk factors for obsessive–compulsive disorder on different parts of the brain. To distinguish between functional brain changes underlying environmentally and genetically mediated obsessive–compulsive disorder, we compared task performance and brain activation during a Tower of London planning paradigm in monozygotic twins discordant (n = 38) or concordant (n = 100) for obsessive–compulsive symptoms. Twins who score high on obsessive–compulsive symptoms can be considered at high risk for obsessive–compulsive disorder. We found that subjects at high risk for obsessive–compulsive disorder did not differ from the low-risk subjects behaviourally, but we obtained evidence that the high-risk subjects differed from the low-risk subjects in the patterns of brain activation accompanying task execution. These regions can be separated into those that were affected by mainly environmental risk (dorsolateral prefrontal cortex and lingual cortex), genetic risk (frontopolar cortex, inferior frontal cortex, globus pallidus and caudate nucleus) and regions affected by both environmental and genetic risk factors (cingulate cortex, premotor cortex and parts of the parietal cortex). Our results suggest that neurobiological changes related to obsessive–compulsive symptoms induced by environmental factors involve primarily the dorsolateral prefrontal cortex, whereas neurobiological changes induced by genetic factors involve orbitofrontal–basal ganglia structures. Regions showing similar changes in high-risk twins from discordant and concordant pairs may be part of compensatory networks that keep planning performance intact, in spite of cortico-striatal-thalamo-cortical deficits.

Role of 2 common variants of 5HT2A gene in medication overuse headache

OBJECTIVE

The aim of the present study was to evaluate a possible involvement of 2 polymorphisms of the serotonin 5HT2A receptor gene (A-1438G and C516T) as risk factors for medication overuse headache (MOH) and whether the presence of these polymorphic variants might determine differences within MOH patients in monthly drug consumption.

BACKGROUND

Despite a growing scientific interest in the mechanisms underlying the pathophysiology of MOH, few studies have focused on the role of genetics in the development of the disease, as well as on the genetic determinants of the inter-individual variability in the number of drug doses taken per month.

METHODS

Our study was performed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism on genomic DNA extracted from peripheral blood of 227 MOH patients and 312 control subjects. Genotype-specific risks were estimated as odds ratios with associated 95% confidence intervals by unconditional logistic regression and adjusted for age and gender. A stepwise multiple linear regression analysis was employed to identify significant predictors of the number of drug doses taken per month.

RESULTS

No significant association was found between 5HT2A A and 1438G and C516T gene polymorphisms and MOH risk. In contrast, a higher consumption of monthly drug doses was observed among 516T 5HT2A carriers (median 50, range 13-120) compared to 516CC patients (median 30, range 12-128) (Mann-Whitney U-test, P = .018). In the stepwise multiple regression analysis, C516T 5HT2A polymorphism (P = .018) and class of overused drug (P = .047) emerged as significant, independent predictors of the monthly drug consumption in MOH patients.

CONCLUSIONS

Although our results do not support a major role of the A-1438G and C516T polymorphic variants of the 5HT2A gene in the susceptibility of MOH, our findings support an influence of the C516T polymorphism on the number of symptomatic drug doses taken and, possibly, on the drug-seeking behavior in these patients.

The genetics of obsessive-compulsive disorder: a review

Obsessive-compulsive disorder (OCD) is a serious psychiatric disorder that affects approximately 2% of the populations of children and adults. Family aggregation studies have demonstrated that OCD is familial, and results from twin studies demonstrate that the familiality is due in part to genetic factors. Only three genome-wide linkage studies have been completed to date, with suggestive but not definitive results. In addition, over 80 candidate gene studies have been published. Most of these studies have focused on genes in the serotonergic and dopaminergic pathways. Unfortunately, none have achieved genome-wide significance, and, with the exception of the glutamate transporter gene, none have been replicated. Future research will require the collaboration of multidisciplinary teams of investigators to (i) achieve sufficiently large samples of individuals with OCD; (ii) apply the state-of-the-art laboratory techniques; and (iii) perform the bioinformatic analyses essential to the identification of risk loci.

A case-control study of sex differences in strategic processing and episodic memory in obsessive-compulsive disorder

Although clinical and genetic data for obsessive-compulsive disorder (OCD) support the hypothesis of sexual dimorphism, the neuropsychological findings remain inconclusive. The aim of our study was to determine whether there are differences in cognitive performance between men and women with OCD as compared with healthy controls (HCs). A neuropsychological battery was administered to 50 patients with OCD (31 men and 19 women) and 50 HCs matched by sex, age, and educational level with patients. We evaluated intelligence, attention, episodic memory, and use of organizational strategies during encoding of verbal and nonverbal information. Male patients scored worse than controls did in measures of nonverbal memory tasks, whereas the cognitive performance of women with OCD was consistent with that of their HC counterparts. These results suggest a distinct pattern of cognitive dysfunction specific to the patients' sex.

The Genetics of Obsessive-Compulsive Disorder

OCD is a psychiatric disorder with a lifetime prevalence of 1-3% and is a significant cause of disability worldwide. Family studies indicate that OCD has a significant hereditable component, with relatives of OCD cases being 4 times more likely to develop the disorder than the general population. Linkage studies in OCD have generally been underpowered and have failed to reach the statistical threshold for genome-wide significance, but they have nevertheless been useful for revealing potential regions of interest for future candidate gene studies. Candidate gene studies in OCD have thus far focused on genes involved in the serotonergic, dopaminergic, and glutamatergic pathways. These studies have been for the most part inconclusive, and failures to replicate have been the norm until very recently. The only genetic association replicated by multiple groups was with a glutamate transporter gene (SLC1A1). Genome-wide association studies in OCD are in progress, but final results have not yet been reported. As with the study of many other psychiatric disorders, an improved understanding of OCD will only be achieved (1) with larger collaborative efforts involving more probands, (2) the use of probands and controls drawn from epidemiologically-based populations rather than clinical samples, (3) developing a more precise phenotypic description of OCD and (4) measuring important environmental influences that affect OCD pathogenesis and severity.

Genetics of early-onset obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is characterized by recurrent, intrusive and disturbing thoughts as well as by repetitive stereotypic behaviors. Epidemiological data are similar in children and adults, i.e., between 1 and 3% of the general population suffer from OCD. Children with OCD are often seriously impaired in their development. OCD, especially of early onset, has been shown to be familial. Several candidate genes of predominantly neurotransmitter systems have been analyzed and a total of three genome-wide linkage scans have been performed until now. Analyses of candidate genes in linkage regions have not provided evidence for their involvement in OCD, with the exception of the glutamate transporter gene SLC1A1 on 9p24. Genome-wide association analyses are in progress and the results will promote further independent replication studies. The consideration of subtypes regarding age of onset, symptom dimensions and/or comorbid disorders is needed.

Genetics of obsessive-compulsive disorder

Obsessive-compulsive disorder is a common debilitating condition affecting individuals from childhood through adult life. There is good evidence of genetic contribution to its etiology, but environmental risk factors also are likely to be involved. The condition probably has a complex pattern of inheritance. Molecular studies have identified several potentially relevant genes, but much additional research is needed to establish definitive causes of the condition.

Gender differences in genetic linkage and association on 11p15 in obsessive-compulsive disorder families

Several clinical and genetic studies have reported gender differences in obsessive-compulsive disorder (OCD). Previously, we conducted a linkage genome scan using multipoint allele-sharing methods to test for linkage in 219 families participating in the OCD Collaborative Genetics Study. When these families were stratified by proband's gender, suggestive linkage to chromosome 11p15 at marker D11S2362 (KAC(all) = 2.92, P = 0.00012) was detected in families with male probands, but not in the ones with female probands. We have since conducted fine mapping with a denser microsatellite marker panel in the region of 11p15, and detected a significant linkage signal at D11S4146 (KAC(all) = 5.08, P < 0.00001) in the families of male probands. Subsequently, 632 SNPs were genotyped spanning a 4.0 Mb region of the 1 LOD unit interval surrounding the linkage peak in the original families and an additional 165 families. Six SNPs were associated with OCD (P < 0.001): two SNPs were identified when all the families were included, and four SNPs only in male proband families. No SNP showed significant association with the OCD phenotype only in the families with a female proband. The results suggest a possible gender effect in the etiology of OCD.

Catechol-O-methyltransferase (COMT): a gene contributing to sex differences in brain function, and to sexual dimorphism in the predisposition to psychiatric disorders

Sex differences in the genetic epidemiology and clinical features of psychiatric disorders are well recognized, but the individual genes contributing to these effects have rarely been identified. Catechol-O-methyltransferase (COMT), which metabolizes catechol compounds, notably dopamine, is a leading candidate. COMT enzyme activity, and the neurochemistry and behavior of COMT null mice, are both markedly sexually dimorphic. Genetic associations between COMT and various psychiatric phenotypes frequently show differences between men and women. Many of these differences are unconfirmed or minor, but some appear to be of reasonable robustness and magnitude; eg the functional Val(158)Met polymorphism in COMT is associated with obsessive-compulsive disorder in men, with anxiety phenotypes in women, and has a greater impact on cognitive function in boys than girls. Sex-specific effects of COMT are usually attributed to transcriptional regulation by estrogens; however, additional mechanisms are likely to be at least as important. Here we review the evidence for a sexually dimorphic influence of COMT upon psychiatric phenotypes, and discuss its potential basis. We conclude that despite the evidence being incomplete, and lacking a unifying explanation, there are accumulating and in places compelling data showing that COMT differentially impacts on brain function and dysfunction in men and women. Since sex differences in the genetic architecture of quantitative traits are the rule not the exception, we anticipate that additional evidence will emerge for sexual dimorphisms, not only in COMT but also in many other autosomal genes.

How the serotonin story is being rewritten by new gene-based discoveries principally related to SLC6A4, the serotonin transporter gene, which functions to influence all cellular serotonin systems

Discovered and crystallized over sixty years ago, serotonin's important functions in the brain and body were identified over the ensuing years by neurochemical, physiological and pharmacological investigations. This 2008 M. Rapport Memorial Serotonin Review focuses on some of the most recent discoveries involving serotonin that are based on genetic methodologies. These include examples of the consequences that result from direct serotonergic gene manipulation (gene deletion or overexpression) in mice and other species; an evaluation of some phenotypes related to functional human serotonergic gene variants, particularly in SLC6A4, the serotonin transporter gene; and finally, a consideration of the pharmacogenomics of serotonergic drugs with respect to both their therapeutic actions and side effects. The serotonin transporter (SERT) has been the most comprehensively studied of the serotonin system molecular components, and will be the primary focus of this review. We provide in-depth examples of gene-based discoveries primarily related to SLC6A4 that have clarified serotonin's many important homeostatic functions in humans, non-human primates, mice and other species.

Role of serotonin in obsessive–compulsive disorder

Obsessive–compulsive disorder (OCD) is a psychiatric disorder consisting of obsessions and compulsions. Over the past two decades, it has been suggested that OCD might be related to the functioning of brain serotonin systems, mainly because of the antiobsessional efficacy of selective serotonin-reuptake inhibitors (SSRIs). Although the efficacy of SSRIs suggests a role of the serotonergic system in OCD, the exact function of serotonin is still unclear. Is the serotonergic system implicated in the pathophysiology of OCD, or is it implicated in the treatment effect in OCD? Do SSRIs compensate for a fundamental abnormality of the serotonergic system, or do SSRIs modulate an intact serotonergic system to compensate for another neurotransmitter mechanism? This review summarizes evidence supporting a role for the serotonin transporter and serotonin receptor subtypes in the pathophysiology and treatment of OCD.

An orbitofrontostriatopallidal pathway for morality: evidence from postlesion antisocial and obsessive-compulsive disorder

INTRODUCTION

A detailed proposal is made to the effect that nonlesional antisocial personality disorder (APD) is, among other things, a dysfunctional hypomoralism and that nonlesional obsessive-compulsive disorder (OCD) is, among other things, a dysfunctional hypermoralism.

METHOD

To provide an empirical test of this proposal, 25 previously published cases of acquired (post lesion) APD and 39 cases of acquired OCD are reviewed and compared with multivariate inference tests.

RESULTS

The acquired APD patients most often present putamenal or pallidal lesions.

CONCLUSION

The ensemble of neurobiological, endocrine, and behavioural traits in APD and OCD, as well as the distinct lesion sites in the acquired variants, support the notion of an orbitofrontostriatopallidal brain system underlying morality.

SERT Ileu425Val in autism, Asperger syndrome and obsessive-compulsive disorder

BACKGROUND

SERT I425V, an uncommon missense single nucleotide polymorphism producing a gain-of-function of the serotonin transporter (SERT), was originally found to segregate with a primarily obsessive-compulsive disorder (OCD) but complexly comorbid phenotype in two unrelated families.

OBJECTIVE

As two individuals with SERT I425V and OCD also had Asperger syndrome (AS), an autism spectrum disorder, and as other rare SERT variants have recently shown significant associations with autism, we set out to extend our original OCD study by genotyping additional autism/AS and OCD samples.

METHODS

Case-control association study of SERT I425V in 210 AS/autism probands and 215 controls, plus 335 OCD probands and their family members.

RESULTS

SERT I425V was not found in any of the individuals with AS/autism, OCD alone or OCD comorbid with AS and other disorders, or in controls. This results in new estimates of SERT I425V having a 1.5% prevalence in 530 individuals with OCD from five unrelated families genotyped by us and by one other group and a 0.23% frequency in four control populations totaling 1300 individuals, yielding a continuing significant OCD-control difference (Fisher's exact test corrected for family coefficient of identity P=0.004, odds ratio=6.54).

CONCLUSION

As several other uncommon, less well quantitated genetic variations occur with an OCD phenotype, including chromosomal anomalies and some other rare gene variants (SGCE, GCH1 and SLITRK1), a tentative conclusion is that OCD resembles other complex disorders in being etiologically heterogeneous and in having both highly penetrant familial subtypes associated with rare alleles or chromosomal anomalies, as well as having a more common, polygenetic form that may involve polymorphisms in such genes as BDNF, COMT, GRIN2beta, TPH2, HTR2A and SLC1A1.

Transmission disequilibrium studies in early onset of obsessive-compulsive disorder for polymorphisms in genes of the dopaminergic system

The dopaminergic system has been shown to be involved in the aetiology of obsessive-compulsive disorder (OCD). Family studies suggest a higher genetic loading in patients with early onset OCD. Our investigation is the first family-based association study concerning polymorphisms in genes of the dopaminergic system in early onset OCD. We studied polymorphisms within the dopamine-4 receptor gene (DRD4), the dopamine transporter gene (DAT1) and the catecholamine-O-methyltransferase gene (COMT). Associations of alleles of DRD4 and COMT with OCD have previously been reported in adults, while a trend towards an association was found for DAT1 alleles. In our study we observed transmission disequilibrium for the 48-bp repeat polymorphism of the DRD4 gene using the ETDT (P=0.047) in 69 trios comprising patients with early onset OCD and both of their parents. Post hoc TDT analysis of the DRD4 showed reduced transmission of the 4-repeat allele and a slightly increased transmission rate for the 7- and the 2-repeat allele. No evidence of transmission disequilibrium was detected for alleles of the DAT1 and COMT polymorphisms. These polymorphisms do not appear to play a major role in the genetic predisposition to early onset OCD in our study group.

Association study between obsessive-compulsive disorder and serotonergic candidate genes

BACKGROUND

To date, research examining the relationship between serotonergic genes and obsessive-compulsive disorder (OCD) has yielded conflicting results. The purpose of this study is to investigate the association between four serotonergic polymorphisms (STin2 VNTR and 5-HTTLPR of the SLC6A4 gene, and A-1438G (rs6311) and T102C (rs6313) of the HTR2A gene) and OCD.

METHODS

99 OCD patients, 456 non-OCD psychiatric patients, and 420 healthy controls from a homogeneous Spanish Caucasian population were genotyped using standard methods.

RESULTS

All groups showed Hardy-Weinberg equilibrium for the analyzed genetic variability. A-1438G and T102C polymorphisms were in complete linkage disequilibrium. OCD patients showed an excess of STin2.12 carriers (12/12, 12/10, and 12/9 genotypes) compared with healthy controls (chi(2) (1)=7.21, corrected p=0.021; OR=3.38, 95% CI=1.32-8.62) and non-OCD psychiatric patients (chi(2) (1)=6.70, corrected p=0.030; OR=3.24, 95% CI=1.27-8.26). However, no differences were found between non-OCD patients and healthy controls (chi(2) (1)=0.05, corrected p>1; OR=1.04, 95% CI=0.72-1.51). No significant differences were found with respect to A-1438G and 5-HTTLPR polymorphisms.

CONCLUSIONS

Our data provide supporting evidence of an association between the STin2 VNTR polymorphism of the SLC6A4 gene and OCD.

Extensive genotyping of the BDNF and NTRK2 genes define protective haplotypes against obsessive-compulsive disorder

BACKGROUND

Family, twin and molecular studies provide increasing evidence for the importance of genetic factors in obsessive-compulsive disorder (OCD). Recent work suggests that brain-derived neurotrophic factor (BDNF) may be involved in OCD pathophysiology. We used a linkage disequilibrium (LD)-mapping approach to investigate the role that BDNF and its specific receptor neurotrophic tyrosine kinase receptor type 2 (NTRK2) may play in increasing susceptibility to OCD.

METHODS

Eight tag single nucleotide polymorphisms (tagSNPs) covering the BDNF gene region and 46 tagSNPs in the NTRK2 region were genotyped in 215 OCD patients and 342 control subjects. Single nucleotide polymorphism association and haplotype analysis were performed. The possible relationship between genetic factors and clinical characteristics including age of OCD onset, tic disorders, clinical dimensions, and family history of OCD were investigated.

RESULTS

Haplotype analysis revealed a significant association between OCD and a five-marker protective haplotype located toward the 5' of the BDNF gene (odds ratio [OR] = .80; 95% confidence interval [CI] = .69-.92; permutation p value = .006) containing the functional valine (Val)66-to-methionine (Met) variant. A significant association between a NTRK2 intronic SNP (rs2378672) and OCD was identified (p < .0001) in female patients under an additive model. A protective haplotype located in intron 19 of NTRK2 was also associated with OCD (OR = .76; 95% CI = .66-.87; permutation p value = .001).

CONCLUSIONS

These findings support a role for the BDNF/NTRK2 signaling pathway in genetic susceptibility to OCD.

Genetic evaluation of the serotonergic system in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a debilitating disorder of unknown etiology with no known lesions, diagnostic markers or therapeutic intervention. The pathophysiology of CFS remains elusive, although abnormalities in the central nervous system (CNS) have been implicated, particularly hyperactivity of the serotonergic (5-hydroxytryptamine; 5-HT) system and hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Since alterations in 5-HT signaling can lead to physiologic and behavioral changes, a genetic evaluation of the 5-HT system was undertaken to identify serotonergic markers associated with CFS and potential mechanisms for CNS abnormality. A total of 77 polymorphisms in genes related to serotonin synthesis (TPH2), signaling (HTR1A, HTR1E, HTR2A, HTR2B, HTR2C, HTR3A, HTR3B, HTR4, HTR5A, HTR6, and HTR7), transport (SLC6A4), and catabolism (MAOA) were examined in 137 clinically evaluated subjects (40 CFS, 55 with insufficient fatigue, and 42 non-fatigued, NF, controls) derived from a population-based CFS surveillance study in Wichita, Kansas. Of the polymorphisms examined, three markers (-1438G/A, C102T, and rs1923884) all located in the 5-HT receptor subtype HTR2A were associated with CFS when compared to NF controls. Additionally, consistent associations were observed between HTR2A variants and quantitative measures of disability and fatigue in all subjects. The most compelling of these associations was with the A allele of -1438G/A (rs6311) which is suggested to have increased promoter activity in functional studies. Further, in silico analysis revealed that the -1438 A allele creates a consensus binding site for Th1/E47, a transcription factor implicated in the development of the nervous system. Electrophoretic mobility shift assay supports allele-specific binding of E47 to the A allele but not the G allele at this locus. These data indicate that sequence variation in HTR2A, potentially resulting in its enhanced activity, may be involved in the pathophysiology of CFS.

Renner T, Wewetzer C, Warnke A. Genetische Befunde bei Zwangsstörungen im Kindes- und Jugendalter und bei Erwachsenen

Zusammenfassung: Im Kindes- und Jugendalter sind Zwangsstörungen bei einer Inzidenz von ein bis zwei Prozent keine Seltenheit und können die Betroffenen in ihrer Entwicklung deutlich beeinträchtigen. Die Erkrankung ist durch wiederkehrende und anhaltende Verhaltensweisen, Gedanken und Impulse gekennzeichnet, die als quälend erlebt werden und sich je nach Entwicklungstand gegen inneren Widerstand aufdrängen und vom Patienten als unsinnig und übertrieben wahrgenommen werden. Die Entstehung von Zwangsstörungen hängt sowohl von Umweltfaktoren, nicht genetischen hirnpathologischen als auch von genetischen Einflussfaktoren ab. Die Mehrheit der bisherigen Ergebnisse bezieht sich dabei auf Untersuchungen im Erwachsenenalter. Es wird eine aktuelle Übersicht über genetische Befunde bei Zwangsstörungen unter besonderer Berücksichtigung des Kindes- und Jugendalters gegeben. Bei jung erkrankten Patienten findet sich eine deutlichere familiäre Belastung. Befunde aus Kopplungs- und Assoziationsstudien sowie Tiermodellen werden vorgestellt und diskutiert. Die phänotypische und genetische Heterogenität von Zwangsstörungen trägt zu den unterschiedlichen Studienergebnissen bei und erfordert für künftige Untersuchungen die Differenzierung von Subtypen, z.B. die Einbeziehung des Alters bei Erkrankungsbeginn, von Symptomdimensionen, geschlechtlichen Besonderheiten und komorbider Störungen.

Molecular genetics of anxiety in mice and men

Human anxiety disorders represent one of the most common mental illnesses. They are complex diseases with both genetic and environmental factors affecting their predisposition. Since the basic neuronal mechanisms are shared across mammalian species, the same set of genes may regulate critical aspects of anxiety in humans and in lower species. In this review, we first summarize findings from human molecular genetic approaches to anxiety disorders or anxiety-related personality traits: genome-wide scans and candidate gene studies in large families or case-control cohorts. We then discuss recent studies that have used genome-wide methods in mouse strains to identify genes that regulate anxiety-like behavior. Although it has been difficult to pinpoint specific susceptibility genes for anxiety disorders, ongoing efforts to collect larger study cohorts and to develop new genetic tools should help in this task. Studies in animals have shown that novel quantitative trait locus (QTL) and functional genomics approaches might lead to the identification of regulators of anxiety in mice, and that these genes can be tested for their involvement in human anxiety disorders. Finally, breakthroughs are expected in the fine-mapping of human and mouse genetic linkage regions and in the identification of novel candidate genes using genome-wide methods in mouse models of anxiety.

Lack of Association of Alcohol Dependence and Habitual Smoking With Catechol-O-methyltransferase

OBJECTIVE

To test whether variation in the gene encoding the enzyme catechol-O-methyltransferase (COMT), which catalyzes the breakdown of dopamine and other catecholamine neurotransmitters, is associated with the risk for alcohol dependence and habitual smoking.

METHODS

Single nucleotide polymophisms (SNPs) were genotyped in a sample of 219 multiplex alcohol-dependent families of European American descent from the Collaborative Study on the Genetics of Alcoholism (COGA). Family-based tests of association were performed to evaluate the evidence of association between the 18 SNPs distributed throughout COMT, including the functional Val158Met polymorphism, and the phenotypes of alcohol dependence, early onset alcohol dependence, habitual smoking, and comorbid alcohol dependence and habitual smoking.

RESULTS

No significant, consistent evidence of association was found with alcohol dependence, early onset alcohol dependence, habitual smoking or the comorbid phenotype. There was no evidence that the functional Val158Met polymorphism, previously reported to be associated with these phenotypes, was associated with any of them.

CONCLUSION

Despite the substantial size of this study, we did not find evidence to support an association between alcohol dependence or habitual smoking and variation in COMT.

Genetic and environmental influences on obsessive-compulsive symptoms in adults: a population-based twin-family study

BACKGROUND

The contribution of genetic factors to obsessive-compulsive (OC) symptoms has not been examined using a large population-based sample of adults. Furthermore, the extent to which there are qualitative and quantitative differences in genetic architecture between men and women with OC symptoms has not been elucidated.

METHOD

We obtained the Young Adult Self Report Obsessive-Compulsive Scale (YASR-OCS) from a group of 5893 monozygotic (MZ) and dizygotic (DZ) twins, and 1304 additional siblings from the population-based Netherlands Twin Register. Structural equation modelling was used to decompose the variation in OC behaviour into genetic and environmental components and analyse quantitative and qualitative sex differences.

RESULTS

Familial resemblance was the same for DZ twins and non-twin siblings, which means that there was no evidence for a special twin environment. The same genetic risk factors for OC behaviour were expressed in men and women. Depending on the choice of fit index, we found small (39% for men and 50% for women) or no sex differences (47% for both men and women) in heritability. The remaining variance in liability was due to individual-specific environment.

CONCLUSIONS

OC behaviour showed a moderate heritability. At most, small quantitative sex differences were found in the genetic architecture of OC behaviour, and no qualitative sex differences.

Obsessive-compulsive and eating disorders: comparison of clinical and personality features

The aim of the present study was to determine whether anorexia nervosa (AN), bulimia nervosa (BN) and obsessive-compulsive disorder (OCD) share clinical and psychopathological traits. The sample consisted of 90 female patients (30 OCD; 30 AN; 30 BN), who had been consecutively referred to the Department of Psychiatry, University Hospital of Bellvitge, Barcelona. All subjects met DSM-IV criteria for those pathologies. The assessment consisted of the Maudsley Obsessive-Compulsive Inventory (MOCI), Questionnaire of obsessive traits and personality by Vallejo, Eating Attitudes Test-40 (EAT-40), Eating Disorder Inventory (EDI), and Beck Depression Inventory (BDI). ANCOVA tests (adjusted for age and body mass index) and multiple linear regression models based on obsessive-compulsiveness, obsessive personality traits and perfectionism, as independent variables, were applied to determine the best predictors of eating disorder severity. On ancova several significant differences were found between obsessive-compulsive and eating-disordered patients (MOCI, P < 0.001; EAT, P < 0.001; EDI, P < 0.001), whereas some obsessive personality traits were not eating disorder specific. A total of 16.7% OCD patients presented a comorbid eating disorder, whereas 3.3% eating disorders patients had an OCD diagnosis. In the eating disorder group, the presence of OC symptomatology was positively associated (r = 0.57, P < 0.001) with the severity of the eating disorder. The results were maintained after adjusting for comorbidity. Although some obsessive-compulsive and eating disorder patients share common traits (e.g. some personality traits especially between OCD and AN), both disorders seem to be clinically and psychopathologically different.

The met(158) allele of catechol-O-methyltransferase (COMT) is associated with obsessive-compulsive disorder in men: case-control study and meta-analysis

Existing data suggest a genetic association between the met(158) allele of catechol-O-methyltransferase (COMT) and obsessive-compulsive disorder (OCD). However, the results are inconclusive and complicated by possible gender differences. We sought to resolve the question in two ways. First, we carried out a new case-control study in 87 adults with OCD and 327 healthy comparison subjects. The study replicated reports of an increased met(158) allele frequency in men with OCD (odds ratio (OR)=1.91, 95% confidence interval (CI) 1.07-3.40, P=0.026), with no effect in women (OR=1.13, 95% CI 0.74-1.72, P=0.56). Second, we performed a meta-analysis of all published case-control data (n=1908 subjects). This revealed an association of COMT met(158) with OCD (OR=1.23, 95% CI 1.06-1.42, P=0.005) and an interaction with gender (z=4.27, P<0.0001). The association between COMT met(158) and OCD was present in men (OR=1.88, 95% CI 1.45-2.44, P<0.001) but not in women (OR=0.98, 95% CI 0.78-1.22, P=0.83). We conclude that COMT may play a role in the genetic aetiology of OCD in men. The biological plausibility of the association is increased by the functionality of the val(158)met polymorphism in terms of its effect on COMT enzyme activity, and by the role of COMT in cortical dopamine signalling and information processing. The finding also extends the evidence for sexual dimorphism in COMT and in OCD.

Association study between the dopamine receptor D(4) gene and obsessive-compulsive disorder

Pharmacological and neuroanatomical evidence suggest the involvement of the dopaminergic system in obsessive-compulsive disorder (OCD). Analysis of the 48-bp dopamine receptor D(4) (DRD4) gene polymorphism in a sample of 210 OCD patients and 202 healthy control subjects showed a significant association (chi(2)=27.5, df=6, p=0.0003). This difference was attributable to a lower frequency of allele 4R in OCD patients compared with the control group (chi(2)=9.33, p=0.0027). However, we did not replicate previous findings of an association between the 7R allele and OCD patients with tics. Finally, we analyzed a sub-sample of 86 OCD families. E-TDT analysis in 70 informative parents did not confirm the association observed in our case-control analysis. In conclusion, the current study cannot exclude an association between DRD4 gene and OCD in the largest sample analyzed. However, further studies will be required to confirm if the DRD4 gene is involved in the pathogenesis of this disorder.

Association studies of serotonin system candidate genes in early-onset obsessive-compulsive disorder

BACKGROUND

Family-based evidence for association at serotonin system genes SLC6A4, HTR1B, HTR2A, and brain-derived neurotrophic factor (BDNF) has been previously reported in obsessive-compulsive disorder (OCD). Early-onset OCD is a more familial form of the disorder.

METHODS

We used the transmission-disequilibrium test of association at common polymorphisms in each of these genes in 54 parent-child trios ascertained through probands with early-onset OCD.

RESULTS

No evidence for association was detected at any of the polymorphisms in the entire set of subjects. Nominally significant association was found at the HTR2A rs6311 polymorphism in subjects with tic disorder and OCD (p = .05), replicating a previous finding in Tourette syndrome and OCD. Nominally significant association was also found for the SLC6A4 HT transporter gene-linked polymorphic region (5-HTTLPR) polymorphism for female subjects (p = .03). Neither association would remain significant after statistical correction for multiple testing. Despite no individual study reporting replication, a pooled analysis of five replication studies of the SLC6A4 5-HTTLPR polymorphism supports association (p = .02).

CONCLUSIONS

Low power across individual association studies in OCD may lead to a false acceptance of the null hypothesis. Accumulation of evidence from multiple studies will be necessary to evaluate the potential role for these genes in contributing to susceptibility to OCD.