Meta-analysis supports association between serotonin transporter (5-HTT) and suicidal behavior

Pharmacogenetics in major depression: a comprehensive meta-analysis

A number of candidate gene studies focused on major depression (MD) and antidepressant (AD) efficacy have been carried out, but results mainly remain inconclusive. We performed a comprehensive meta-analysis of published candidate gene studies focused on AD efficacy in MD to evaluate the cumulative evidence. A random-effect model was applied to study the polymorphisms with genotypic counts available from at least three independent studies. On the base of previous evidence, the analysis was stratified by ethnicity (Caucasian, Asian, and other/mixed), and AD class (SSRIs and mixed/other ADs). Genotypic data were available for 16 polymorphisms in 11 genes. After the exclusion of 5-HTTLPR in SLC6A4 included in another recent meta-analysis, 15 polymorphisms in 11 genes were included in the present meta-analysis (BDNF rs6265, SLC6A4 STin2, HTR1A rs6295, HTR2A rs6311, rs6313 and rs7997012, HTR6 rs1805054, TPH1 rs1800532, SLC6A2 rs5569, COMT rs4680, GNB3 rs5443, FKBP5 rs1360780 and rs3800373, and ABCB1 rs1045642 and rs2032582). Our results suggested that BDNF rs6265 (Val66Met) heterozygous genotype was associated with better SSRIs response compared to the homozygous genotypes, particularly in Asians (OR=1.53, 95%CI 1.12-2.07, p=0.007). SLC6A4 STin2, HTR2A rs6311 and rs7997012, GNB3 rs5443, FKBP5 rs1360780 and rs3800373, and ABCB1 rs2032582 showed associations with AD efficacy, but these results were highly dependent on one or two single studies. In conclusion, our findings suggested the BDNF Val66Met as the best single candidate involved in AD response, with a selective effect on SSRI treatment. Our overall results supported no major effect of any single gene variant on AD efficacy.

Gene environment interaction studies in depression and suicidal behavior: An update

Increasing evidence supports the involvement of both heritable and environmental risk factors in major depression (MD) and suicidal behavior (SB). Studies investigating gene-environment interaction (G × E) may be useful for elucidating the role of biological mechanisms in the risk for mental disorders. In the present paper, we review the literature regarding the interaction between genes modulating brain functions and stressful life events in the etiology of MD and SB and discuss their potential added benefit compared to genetic studies only. Within the context of G × E investigation, thus far, only a few reliable results have been obtained, although some genes have consistently shown interactive effects with environmental risk in MD and, to a lesser extent, in SB. Further investigation is required to disentangle the direct and mediated effects that are common or specific to MD and SB. Since traditional G × E studies overall suffer from important methodological limitations, further effort is required to develop novel methodological strategies with an interdisciplinary approach.

Meta-analyses of the 5-HTTLPR polymorphisms and post-traumatic stress disorder

Objective

To conduct a meta-analysis of all published genetic association studies of 5-HTTLPR polymorphisms performed in PTSD cases

Methods Data Sources

Potential studies were identified through PubMed/MEDLINE, EMBASE, Web of Science databases (Web of Knowledge, WoK), PsychINFO, PsychArticles and HuGeNet (Human Genome Epidemiology Network) up until December 2011. Study Selection: Published observational studies reporting genotype or allele frequencies of this genetic factor in PTSD cases and in non-PTSD controls were all considered eligible for inclusion in this systematic review. Data Extraction: Two reviewers selected studies for possible inclusion and extracted data independently following a standardized protocol. Statistical analysis: A biallelic and a triallelic meta-analysis, including the total S and S' frequencies, the dominant (S+/LL and S'+/L'L') and the recessive model (SS/L+ and S'S'/L'+), was performed with a random-effect model to calculate the pooled OR and its corresponding 95% CI. Forest plots and Cochran's Q-Statistic and I² index were calculated to check for heterogeneity. Subgroup analyses and meta-regression were carried out to analyze potential moderators. Publication bias and quality of reporting were also analyzed.

Results

13 studies met our inclusion criteria, providing a total sample of 1874 patients with PTSD and 7785 controls in the biallelic meta-analyses and 627 and 3524, respectively, in the triallelic. None of the meta-analyses showed evidence of an association between 5-HTTLPR and PTSD but several characteristics (exposure to the same principal stressor for PTSD cases and controls, adjustment for potential confounding variables, blind assessment, study design, type of PTSD, ethnic distribution and Total Quality Score) influenced the results in subgroup analyses and meta-regression. There was no evidence of potential publication bias.

Conclusions

Current evidence does not support a direct effect of 5-HTTLPR polymorphisms on PTSD. Further analyses of gene-environment interactions, epigenetic modulation and new studies with large samples and/or meta-analyses are required.

An association study of suicide and candidate genes in the serotonergic system

INTRODUCTION

Strong evidence demonstrates a genetic susceptibility to suicidal behaviour and a relationship between suicide and mental disorders. The aim of this study was to test for association between suicide and five selected genetic variants, which had shown association with suicide in other populations.

METHOD

We performed a nationwide case-control study on all suicide cases sent for autopsy in Denmark between the years 2000 and 2007. The study comprised 572 cases and 1049 controls and is one of the largest genetic studies in completed suicide to date. The analysed markers were located within the Serotonin Transporter (SLC6A4), Monoamine Oxidase-A (MAOA) and the Tryptophan Hydroxylase I and II (TPH1 and TPH2) genes.

RESULTS

None of the genetic markers within SLC6A4, MAOA, TPH1 and TPH2 were significantly associated with completed suicide or suicide method in the basic association tests. Exploratory interaction test showed that the minor allele of rs1800532 in TPH1 has a protective effect for males younger than 35 years and females older than 50 years, whereas for the oldest male subjects, it tended to be a risk factor. We also observed a significant interaction between age-group and the 5-HTTLPR genotype (with and without rs25531) in SLC6A4. The long allele or high expression allele tends to have a protective effect in the middle age-group.

LIMITATION

We only analysed a limited number of genetic variants.

CONCLUSION

None of the analysed variants are strong risk factors. To reveal a better understanding of the genes involved in suicide, we suggest future studies should include both genetic and non-genetic factors.

Associations of the 5-hydroxytryptamine (serotonin) receptor 1B gene (HTR1B) with alcohol, cocaine, and heroin abuse

Abnormal serotonergic pathways are implicated in numerous neuropsychiatric disorders including alcohol and drug dependence (abuse). The human 5-hydroxytryptamine (serotonin) receptor 1B, encoded by the HTR1B (5-HT1B) gene, is a presynaptic serotonin autoreceptor that plays an important role in regulating serotonin synthesis and release. Although there was evidence of associations of the HTR1B gene variants in the etiologies of substance use disorders, negative findings were also reported. To clarify the roles of commonly reported single nucleotide polymorphisms (SNPs) of the HTR1B gene underlying alcohol and drug dependence (abuse), we performed a meta-analysis based on the available genotype data from individual candidate gene-based association studies. Evidence of association was found between the functional SNP -161A>T (rs130058) and alcohol, cocaine, and heroin dependence (e.g., P = 0.03 and odds ratio (OR) = 1.2 (1.02, 1.42) in the combined European, Asian, African, and Hispanic populations). SNP -261T>G (rs11568817) also showed evidence of association but with different directions in Europeans and non-Europeans (e.g., P = 0.0018 with OR = 1.42 (1.14, 1.76) and P = 0.01 with ORs = 0.5 (0.3, 0.85), respectively). This meta-analysis supports the associations of HTR1B -261T>G and -161A>T with alcohol and drug abuse and further investigations are warranted in larger samples.

The role of the serotonergic system at the interface of aggression and suicide

Alterations in serotonin (5-HT) neurochemistry have been implicated in the aetiology of all major neuropsychiatric disorders, ranging from schizophrenia to mood and anxiety-spectrum disorders. This review will focus on the multifaceted implications of 5-HT-ergic dysfunctions in the pathophysiology of aggressive and suicidal behaviours. After a brief overview of the anatomical distribution of the 5-HT-ergic system in the key brain areas that govern aggression and suicidal behaviours, the implication of 5-HT markers (5-HT receptors, transporter as well as synthetic and metabolic enzymes) in these conditions is discussed. In this regard, particular emphasis is placed on the integration of pharmacological and genetic evidence from animal studies with the findings of human experimental and genetic association studies. Traditional views postulated an inverse relationship between 5-HT and aggression and suicidal behaviours; however, ample evidence has shown that this perspective may be overly simplistic, and that such pathological manifestations may reflect alterations in 5-HT homoeostasis due to the interaction of genetic, environmental and gender-related factors, particularly during early critical developmental stages. The development of animal models that may capture the complexity of such interactions promises to afford a powerful tool to elucidate the pathophysiology of impulsive aggression and suicidability, and identify new effective therapies for these conditions.

Analysis of four genes involved in the neurodevelopment shows association of rs4307059 polymorphism in the cadherin 9/10 region with completed suicide

BACKGROUND

We hypothesized that DNA variants affecting neurodevelopment such as rs4307059 (CDH10/CDH9), rs930752 (NRXN1), rs6265 (BDNF) or rs10868235 (NTRK2) may predispose to completed suicide.

METHODOLOGY

We used a case-control two-stage approach based on a discovery cohort (557 cases and ∼550 controls) and replication cohort (159 cases and 186 controls). The suicides were ascertained as consecutive cases autopsied at the Department of Forensic Medicine, Medical University of Warsaw, Poland.

RESULTS

In the discovery cohort we found an association between suicide and the CC genotype in the rs4307059 polymorphism (OR 1.64, p = 0.012). The trend for an overrepresentation of the CC homozygotes among suicides was replicated in the second cohort (OR 1.97, p = 0.056). Analysis in the pooled cohorts showed that rs4307059 CC was associated with completed suicide (OR 1.71, p = 0.002) also after Bonferroni correction (p(cor.) = 0.024). In an exploratory search for genotype-phenotype correlation we found that males with the rs4307059 CC genotype committed suicide earlier than those with CT/TT genotypes (p = 0.049).

CONCLUSIONS

The CC genotype of rs4307059 located in the region between CDH9 and CDH10 is associated with completed suicide in a Polish cohort.

Clinical implications of genetic variation in the serotonin transporter promoter region: a review

OBJECTIVE

To determine the state of the art in understanding the role of genetic variation in the serotonin transporter (5-HTT) promoter region (5-HTTLPR) in the development of a depressive episode and in its response to treatment.

DATA SOURCES

PubMed and Ovid were used to search for articles published prior to December 2007 utilizing the key words serotonin transporter, 5-HTT, 5-HTTLPR, serotonin transporter gene, and SLC6A4.

STUDY SELECTION

All studies were reviewed, but case reports and small case series were excluded.

DATA EXTRACTION

All relevant articles were read by at least 2 of the coauthors and notes regarding study design, measures, data analysis, and findings were later used to construct the review.

DATA SYNTHESIS

A common genetic variant, the short allele, in which 44 base pairs are missing from the promoter of SLC6A4, is associated with a greater risk for developing a major depressive disorder in patients following exposure to adversity. This association appears to be most important in the early stages of the depressive disorder. Additionally, the likelihood of a positive response to antidepressant treatment may be reduced in these patients in terms of delayed response, greater adverse event load, or, in bipolar patients, mania induction and rapid cycling.

CONCLUSIONS

Selected genetic testing of patients with a recent history of significant adversity may be a reasonable tool that can enlighten treatment options and the course of illness. Ongoing work with the short allele of 5-HTT may also inform clinical guidelines of long-term treatment with antidepressants.

Genetic epistasis in female suicide attempters

BACKGROUND

Complex behaviors such as suicidal behavior likely exhibit gene-gene interactions. The main aim of this study is to explore potential single nucleotide polymorphisms combinations with epistatic effect in suicidal behavior using a data mining tool (Multifactor Dimensionality Reduction).

METHODS

Genomic DNA from peripheral blood samples was analyzed using SNPlex Technology. Multifactor Dimensionality Reduction was used to detect epistatic interactions between single nucleotide polymorphisms from the main central nervous system (CNS) neurotransmitters (dopamine: 9; noradrenaline: 19; serotonin: 23; inhibitory neurotransmitters: 60) in 889 individuals (417 men and 472 women) aged 18 years or older (585 psychiatric controls without a history of suicide attempts, and 304 patients with a history of suicide attempts). Individual analysis of association between single nucleotide polymorphisms and suicide attempts was estimated using logistic regression models.

RESULTS

Multifactor Dimensionality Reduction showed significant epistatic interactions involving four single nucleotide polymorphisms in female suicide attempters with a classification test accuracy of 60.7% (59.1%-62.4%, 95% CI): rs1522296, phenylalanine hydroxylase gene (PAH); rs7655090, dopamine receptor D5 gene (DRD5); rs11888528, chromosome 2 open reading frame 76, close to diazepam binding inhibitor gene (DBI); and rs2376481, GABA-A receptor subunit γ3 gene (GABRG3). The multivariate logistic regression model confirmed the relevance of the epistatic interaction [OR(95% CI)=7.74(4.60-13.37)] in females.

CONCLUSIONS

Our results suggest an epistatic interaction between genes of all monoamines and GABA in female suicide attempters.

Association between a genetic variant in the serotonin transporter gene (SLC6A4) and suicidal behavior in patients with schizophrenia

Background

The serotonin (5-hydroxytryptamin; 5-HT) system has a central role in the circuitry of cognition and emotions. Multiple lines of evidence suggest that genetic variation in the serotonin transporter gene (SLC6A4; 5-HTT) is associated with schizophrenia and suicidal behavior. In this study, we wanted to elucidate whether SLC6A4 variations is involved in attempted suicide among patients with schizophrenia in a Scandinavian case–control sample.

Methods

Patients diagnosed with schizophrenia from three Scandinavian samples were assessed for presence or absence of suicide attempts, based on record reviews and interview data. Seven SLC6A4 single nucleotide polymorphisms (SNPs) were genotyped in 837 schizophrenia patients and 1,473 control individuals. Association analyses and statistical evaluations were performed with the program UNPHASED (version 3.0.9).

Results

We observed an allele association between the SNP rs16965628, located in intron one of SLC6A4, and attempted suicide (adjusted p-value 0.01), among patients with schizophrenia. No association was found to a diagnosis of schizophrenia, when patients were compared to healthy control individuals.

Conclusion

The gene SLC6A4 appears to be involved in suicidal ideation among patients with schizophrenia. Independent replication is needed before more firm conclusions can be drawn.

Strong protective effect of the aldehyde dehydrogenase gene (ALDH2) 504lys (*2) allele against alcoholism and alcohol-induced medical diseases in Asians

Alcohol is oxidized to acetaldehyde, which in turn is oxidized to acetate. The aldehyde dehydrogenase 2 gene (ALDH2) is the most important gene responsible for acetaldehyde metabolism. Individuals heterozygous or homozygous for the lys (A or *2) allele at the single nucleotide polymorphism (SNP) glu504lys (rs671) of ALDH2 have greatly reduced ability to metabolize acetaldehyde, which greatly decreases their risk for alcohol dependence (AD). Case-control studies have shown association between this SNP and alcohol dependence as well as alcohol-induced liver disease. However, some studies have produced insignificant results. Using cumulative data from the past 20 years predominately from Asian populations (from both English and Chinese publications), this meta-analysis sought to examine and update whether the aggregate data provide new evidence of statistical significance for the proposed association. Our results (9,678 cases and 7,331 controls from 53 studies) support a strong association of alcohol abuse and dependence, with allelic P value of 3 × 10(-56) and OR of 0.23 (0.2, 0.28) under the random effects model. The dominant model (lys-lys + lys-glu vs. glu-glu) also showed strong association with P value of 1 × 10(-44) and OR of 0.22 (0.18, 0.27). When stricter criteria and various sub-group analyses were applied, the association remained strong (for example, OR = 0.23 (0.18, 0.3) and P = 2 × 10(-28) for the alcoholic patients with alcoholic liver disease, cirrhosis, or pancreatitis). These findings provide confirmation of the involvement of the human ALDH2 gene in the pathogenesis of AD as well as alcohol-induced medical illnesses in East-Asians.

Connectomic intermediate phenotypes for psychiatric disorders

Psychiatric disorders are phenotypically heterogeneous entities with a complex genetic basis. To mitigate this complexity, many investigators study so-called intermediate phenotypes (IPs) that putatively provide a more direct index of the physiological effects of candidate genetic risk variants than overt psychiatric syndromes. Magnetic resonance imaging (MRI) is a particularly popular technique for measuring such phenotypes because it allows interrogation of diverse aspects of brain structure and function in vivo. Much of this work however, has focused on relatively simple measures that quantify variations in the physiology or tissue integrity of specific brain regions in isolation, contradicting an emerging consensus that most major psychiatric disorders do not arise from isolated dysfunction in one or a few brain regions, but rather from disturbed interactions within and between distributed neural circuits; i.e., they are disorders of brain connectivity. The recent proliferation of new MRI techniques for comprehensively mapping the entire connectivity architecture of the brain, termed the human connectome, has provided a rich repertoire of tools for understanding how genetic variants implicated in mental disorder impact distinct neural circuits. In this article, we review research using these connectomic techniques to understand how genetic variation influences the connectivity and topology of human brain networks. We highlight recent evidence from twin and imaging genetics studies suggesting that the penetrance of candidate risk variants for mental illness, such as those in SLC6A4, MAOA, ZNF804A, and APOE, may be higher for IPs characterized at the level of distributed neural systems than at the level of spatially localized brain regions. The findings indicate that imaging connectomics provides a powerful framework for understanding how genetic risk for psychiatric disease is expressed through altered structure and function of the human connectome.

Parent of origin effect and allelic expression imbalance of the serotonin transporter in bipolar disorder and suicidal behaviour

Suicide and suicidal behaviour are a major health concern worldwide particularly in patients with mood disorders. Family, adoption and twin studies show that genetics influences suicidal behaviour. The serotonin transporter (5HTT) plays an important role in the pathophysiology of mood disorders and may also be involved in suicidal behaviour since 5HTT binding is decreased in the brain of suicide completers. Because the effect of genomic imprinting in the 5HTT gene on suicidal behaviour has not been investigated, we analysed the parent-of-origin effect (POE) of four 5HTT markers and the differential expression of the 5HTT G2651T (rs1042173) alleles in suicide attempters affected by bipolar disorder. We performed a family based association study and ETDT/QTDT analyses of the rs25531, HTTLPR, VNTR-2 and G2651T polymorphisms in 312 nuclear families with at least one subject affected by bipolar disorder. The main outcomes investigated in this study are bipolar disorder diagnosis, suicide attempts, suicidal behaviour severity and age at onset of bipolar disorder. We also compared the allele-specific mRNA levels in lymphoblastoid cells from 13 bipolar suicide attempters and 8 bipolar non-suicide attempters. Allele 2651T was transmitted significantly more often to bipolar patients (P = 0.042). There was no significant difference between maternal and paternal transmission ratios. Furthermore, there was no significant difference in the ratio of T/G-specific mRNA expression between bipolar attempters and non-attempters. These data do not support a role for differential allelic expression of 5HTT for suicidal behaviour in bipolar disorder. Small sample size and the fact that RNA was obtained from lymphoblastoid cell lines were some of the limitations of this study.

Understanding the molecular pharmacology of the serotonergic system: using fluoxetine as a model

OBJECTIVES

Serotonin is a monoamine neurotransmitter that is widely distributed in the body and plays an important role in a variety of psychological and other body functions such as mood, sexual desire and function, appetite, sleep, memory and learning, temperature regulation and social behaviour. This review will assess the use of fluoxetine, one of the most commonly used selective serotonin reuptake inhibitors, as a model for understanding the molecular pharmacology of the serotoninergic system.

KEY FINDINGS

Seven serotonin receptor families have been discovered to date. All serotonin receptors, except 5-HT(3), are G-protein coupled, seven transmembrane receptors that activate an intracellular second messenger cascade. The 5-HT(3) receptor is a ligand-gated ion channel. Furthermore, 5-HT(1A) receptors are known as autoreceptors since their stimulation inhibits the release serotonin in nerve terminals. A transporter protein found in the plasma membrane of serotonergic neurones is responsible for the reuptake of this neurotransmitter. Selective serotonin reuptake inhibitors, such as fluoxetine, act primarily at the serotonin transporter protein and have limited, if any, reaction with other neurotransmitter systems. Selective serotonin reuptake inhibitors appear to bind with the serotonin transporter with different rates of occupancy, duration and potency.

SUMMARY

The following review focuses on the interaction of serotonin with this membrane transporter in the body and assesses the use of fluoxetine as a reference drug in the understanding of this interaction.

Serotonin-related gene pathways associated with undifferentiated somatoform disorder

It has been suggested that serotonergic hypofunction and serotonergic pathway genes underlie the somatic symptoms of somatoform disorders. We examined a variety of serotonin-related gene polymorphisms to determine whether undifferentiated somatoform disorder is associated with specific serotonin-related gene pathways. Serotonin-related polymorphic markers were assessed using single nucleotide polymorphism (SNP) genotyping. One hundred and two patients with undifferentiated somatoform disorder and 133 healthy subjects were enrolled. The genotype and allele frequencies of tryptophan hydroxylase (TPH)1 A218C, TPH2 rs1386494, serotonin receptor 2A-T102C (5-HTR 2A-T102C), 5-HTR 2A-G1438A and serotonin transporter (5HTTLPR) gene were compared between the groups. The Hamilton Rating Scale for Depression and the somatization subscale of the Symptom Checklist-90-Revised (SCL-90-R) were used for psychological assessment. Patients with undifferentiated somatoform disorder had higher frequencies of the TPH1 C allele than healthy controls (p=0.02) but the difference was not significant after Bonferroni correction. The frequency of TPH1 genotype also did not differ significantly between the patients and the healthy controls, nor did TPH2 rs1386494, 5-HTR 2A-T102C, 5-HTR 2A-G1438A or 5HTTLPR allele and genotype frequencies differ significantly between the two groups. These findings suggest that a variety of serotonin-related gene pathways are unlikely to be definite genetic risk factors for undifferentiated somatoform disorder. Therefore, the pathogenesis of the disorder may be related to epigenetic factors, including psychosocial and cultural factors. Nonetheless, future studies need to include a larger sample of subjects and polymorphisms of more serotonin-related gene variants.

Strong association of the alcohol dehydrogenase 1B gene (ADH1B) with alcohol dependence and alcohol-induced medical diseases

BACKGROUND

The alcohol dehydrogenase 1B gene (ADH1B) is hypothesized to affect predisposition to alcohol dependence (AD) and abuse. A variant of the ADH1B gene (rs1229984 or Arg48His; previously referred to as Arg [*1] and His [*1]) has been reported to be associated with reduced rates of alcohol and drug dependence. Different studies have produced inconclusive results regarding association between rs1229984 (or rs2066702) and substance dependence.

METHODS

Using the cumulative association study literature from the past 21 years from both English- and Chinese-language publications, this meta-analysis seeks to clarify the contradictory findings and to examine whether the aggregate data provide new evidence of significant association.

RESULTS

The results, based on a large sample size (9638 cases and 9517 controls), suggested strong associations with alcohol dependence and abuse as well as alcohol-induced liver diseases, with an allelic (Arg vs. His) p value being 1 × 10(-36) and odds ratio (OR) (95% confidence intervals [CI]) 2.06 (1.84-2.31) under the random effects model. The dominant and recessive models produced larger ORs of 2.17 and 3.05, respectively. When more stringent criteria and subgroup analyses were imposed, the associations remained consistent and were strongest in various Asian groups (allelic p = 7 × 10(-42) and OR (95% CI) = 2.24 [1.99-2.51] with ORs of 2.16 and 4.11 for dominant and recessive models, respectively).

CONCLUSIONS

Our findings provide further strong evidence for the involvement of the ADH1B gene in the pathogenesis of alcohol dependence and abuse as well as for some alcohol-induced medical diseases in the multiple ethnic populations--in particular, certain Asian populations.

Relationship between a history of a suicide attempt and treatment outcomes in patients with depression

This study aimed to investigate the sociodemographic and clinical correlates of a history of a suicide attempt in people with depression and their relationship with treatment outcomes and subsequent suicidal ideation and deliberate self-harm. Patients with depressive disorders according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were recruited from 18 hospitals across South Korea. Data on sociodemographic and clinical characteristics were obtained, and scales assessing depression, anxiety, and general functioning were administered during the first 12 weeks of antidepressant treatment. Baseline characteristics, responses to treatment, and suicidal ideation/deliberate self-harm during the follow-up period were compared according to a reported history or not of a suicide attempt. In a total of 723 participants, 143 (19.8%) with a history of a suicide attempt had an earlier age of onset, longer duration of illness, and a greater number of depressive episodes. Levels of depression and anxiety were significantly higher at baseline in this group who also experienced significantly lower remission and response rates, as well as longer time to remission. The case group was more likely to experience new suicidal ideation and carry out a deliberate self-harm act during the 12-week treatment period. In conclusion, a history of a suicide attempt in a Korean population with depression was characterized by more severe psychopathology, poorer treatment outcomes, and higher subsequent suicidal ideation and self-harm. Therefore, more intensive and longer-term treatment with particular ongoing clinical attention to risk is indicated in patients with these distinct, chronic, and severe forms of depression and ongoing high suicide risk.

Role of serotonergic-related systems in suicidal behavior: Data from a case-control association study

OBJECTIVE

To investigate whether functional polymorphisms directly (HTR2A and SLC6A4 genes) or indirectly (IL-1 gene complex, APOE and ACE genes) related with serotonergic neurotransmission were associated with suicidal behavior.

SUBJECTS AND METHODS

227 suicide attempters, 686 non-suicidal psychiatric patients, and 420 healthy controls from a homogeneous Spanish Caucasian population were genotyped using standard methods.

RESULTS

There were no differences in genotype frequencies between the three groups. The -1438A/G [χ(2) (df)=9.80 (2), uncorrected p=0.007] and IL-1α -889C/T [χ(2) (df)=8.76 (2), uncorrected p=0.013] genotype frequencies between impulsive and planned suicide attempts trended toward being different (not significant after Bonferroni correction). Suicide attempts were more often impulsive in the presence of -1438G/G or IL-1α -889C/T or C/C genotypes. There was interaction between the polymorphism 5-HTTLPR and age [LRT (df)=6.84 (2), p=0.033] and between the polymorphisms APOE and IL-1RA (86bp)(n) [LRT (df)=12.21 (4), p=0.016] in relation to suicide attempt lethality.

CONCLUSION

These findings further evidence the complexity of the association between genetics and suicidal behavior, the need to study homogenous forms of the behavior and the relevance of impulsive and aggressive traits as endophenotypes for suicidal behavior.

Incomplete coverage of candidate genes: a poorly considered bias

Current genetic investigations are performed both on the basis of a rational and biologically based choice of candidate genes and through genome wide scans. Nonetheless, lack of replication is a common problem in psychiatric genetics as well as in other genetic fields. There are a number of reasons for this inconsistency, among them a well known but poorly considered issue is gene coverage. The aim of the present paper is to focus on this well known and defectively deemed bias, especially when a candidate gene approach is chosen. The rational and the technical feasibility of this proposal are discussed as well as a survey of current investigations. The known consistent methodology to fix this bias is also discussed.

The role of child sexual abuse in the etiology of suicide and non-suicidal self-injury

OBJECTIVE

To address the best available scientific evidence on the role of child sexual abuse in the etiology of suicide and non-suicidal self-injury.

METHOD

Seven databases were searched, supplemented with hand-search of reference lists from retrieved papers. The author and a psychiatrist independently evaluated the eligibility of all studies identified, abstracted data, and assessed study quality. Disagreements were resolved by consensus.

RESULTS

Four reviews, including about 65,851 subjects from 177 studies, were analyzed. There is evidence that child sexual abuse is a statistically significant, although general and non-specific, risk factor for suicide and non-suicidal self-injury. The relationship ranges from small to medium in magnitude and is moderated by sample source and size. Certain biological and psychosocial variables, such as serotonin hypoactivity and genes, family dysfunction, other forms of maltreatment, and some personality traits and psychiatric disorders, may either act independently or interact with child sexual abuse to promote suicide and non-suicidal self-injury in abuse victims, with child sexual abuse conferring additional risk, either as a 'distal' and indirect cause or as a 'proximal' and direct cause.

CONCLUSION

Child sexual abuse should be considered one of the several risk factors for suicide and non-suicidal self-injury and included in multifactorial etiological models.

The possible contributory role of the S allele of 5-HTTLPR in the emergence of suicidality

Suicide is a complex and challenging human phenomenon, and, although knowledge is expanding concerning its risk factors, its background is still not fully understood. There is currently an increasing interest in genetic factors associated with suicide, since these may lead to the emergence of personality traits and temperaments that may be long-term predictors of suicidal behaviour. One of the most likely genetic candidates in the background of suicide is the 5-HTTLPR polymorphism of the serotonin transporter gene. This review focused on papers published on the association of the 5-HTTLPR polymorphism of the serotonin transporter gene and suicidal behaviour as well as research on possible endophenotypes related to suicide. Although there are contradictory results, several studies and meta-analyses support the idea that the S allele plays a role in the background of violent suicide. However, in order to be able to delineate the genetic background of suicide, different types of suicidal behaviour should be distinguished, since studies indicate that these may have different genetic factors. Also, personality traits and temperaments should be identified that may play a modulating role between genetic factors and suicidal behaviour. So far, neuroticism, affective temperaments, and impulsive aggression have been found to be associated with both the S allele and suicidal behaviour. This study aimed to integrate findings concerning possible endophenotypes modulating between genetic factors and manifested suicidal behaviour.

Recent molecular genetic studies and methodological issues in suicide research

Suicide behavior (SB) spans a spectrum ranging from suicidal ideation to suicide attempts and completed suicide. Strong evidence suggests a genetic susceptibility to SB, including familial heritability and common occurrence in twins. This review addresses recent molecular genetic studies in SB that include case-control association, genome gene-expression microarray, and genome-wide association (GWA). This work also reviews epigenetics in SB and pharmacogenetic studies of antidepressant-induced suicide. SB fulfills criteria for a complex genetic phenotype in which environmental factors interact with multiple genes to influence susceptibility. So far, case-control association approaches are still the mainstream in SB genetic studies, although whole genome gene-expression microarray and GWA studies have begun to emerge in recent years. Genetic association studies have suggested several genes (e.g., serotonin transporter, tryptophan hydroxylase 2, and brain-derived neurotrophic factor) related to SB, but not all reports support these findings. The case-control approach while useful is limited by present knowledge of disease pathophysiology. Genome-wide studies of gene expression and genetic variation are not constrained by our limited knowledge. However, the explanatory power and path to clinical translation of risk estimates for common variants reported in genome-wide association studies remain unclear because of the presence of rare and structural genetic variation. As whole genome sequencing becomes increasingly widespread, available genomic information will no longer be the limiting factor in applying genetics to clinical medicine. These approaches provide exciting new avenues to identify new candidate genes for SB genetic studies. The other limitation of genetic association is the lack of a consistent definition of the SB phenotype among studies, an inconsistency that hampers the comparability of the studies and data pooling. In summary, SB involves multiple genes interacting with non-genetic factors. A better understanding of the SB genes by combining whole genome approaches with case-control association studies, may potentially lead to developing effective screening, prevention, and management of SB.

Role of mother's genes and environment in postpartum depression

Most studies of human molecular genetics and social environment interactions on health have relied heavily on the classic diathesis-stress model that treats genetic variations and environments as being either "risky" or "protective." The biological susceptibility model posits that some individuals have greater genetic reactivity to stress, leading to worse outcomes in poor environments, but better outcomes in rich environments. Using a nontruncated measure of a chronic environmental stressor--socioeconomic status--measured by education, and two polymorphisms (5-HTTLPR and STin2 VNTR) of the serotonin transporter gene (5-HTT), we find strong evidence that some women are genetically more reactive to the environment, resulting in a crossover of risks of postpartum depression for the most reactive groups. We discuss how our approach and findings provide a framework for understanding some of the confusion in the gene-environment interaction literature on stress, 5-HTT, and depression.

Suicide in schizophrenia

Schizophrenia is a disorder with an estimated suicide risk of 4-5%. Many factors are involved in the suicidal process, some of which are different from those in the general population. Clinical risk factors include attempted suicide, depression, male gender, substance abuse and hopelessness. Biosocial factors, such as a high intelligence quotient and high level of premorbid function, have also been associated with an increased risk of suicide in patients with schizophrenia. Suicide risk is especially high during the first year after diagnosis. Many of the suicides occur during hospital admission or soon after discharge. Management of suicide risk includes both medical treatment and psychosocial interventions. Still, risk factors are crude; efforts to predict individual suicides have not proved useful and more research is needed.

Mixture regression analysis on age at onset in bipolar disorder patients: investigation of the role of serotonergic genes

Bipolar Disorder (BPD) is a complex psychiatric disease with a relevant underlying genetic basis. HTR2A T102C, HTR2C Cys23Ser, SLC6A4 5-HTTLPR and rs25531 polymorphisms were genotyped in 230 BPD patients and inserted as covariates in a mixture regression model of age at onset (AAO). 5-HTTLPR polymorphism associated with early onset component under recessive and additive model. HTR2A T102C, HTR2C Cys23Ser and 5-HTTLPR interaction terms associated with early onset component under dominant, recessive and additive model. These findings suggest a role of genes codifying for elements of the serotonergic system in influencing the AAO in BPD.

Is the serotonin transporter polymorphism (5-HTTLPR) a potential marker for suicidal behavior in bipolar disorder patients?

BACKGROUND

Suicide prediction is a huge challenge for mental health workers. Structured interviews based on epidemiological and clinical factors don't show effectiveness for suicide prevention. Biological markers, such as 5-HTTLPR, could help for identification of potential suicide attempters.

METHODS

We evaluated 198 bipolar patients and 103 health controls, using a structured interview according to DSM-IV criteria. Genotyping, blind of clinical assessment for identification of S carriers and structured interviews were performed in order to describe clinical and epidemiological factors which could be associated with suicide behavior. Statistical analyses were calculated by the x(2) test and logistic regression model.

RESULTS

We found that 26.77% and 16.67% had a lifetime history of non violent suicide attempt and violent suicide attempt, respectively. The clinical factors associated with violent and non violent suicide attempt had several differences. Violent suicide attempters had an earlier illness onset and had a higher number of psychiatric comorbidities (borderline personality disorder, panic disorder and alcoholism). The frequency of S allele carriers was higher only in those patients who had made a violent suicide attempt in their lifetime (x(2)=16.969; p=0.0001). In a logistic regression model including these factors, S allele carrier (5-HTTLPR) was the only factor associated with violent suicide attempt.

LIMITATIONS

Sample size and retrospective assessment of suicide behavior history are the limitations of this study.

CONCLUSIONS

Our study showed that serotonin polymorphism (5-HTTLPR) is strongly associated with violent suicidal behavior in BD patients. If confirmed, our results could be an important step to create a genetic tool for long-term suicide prediction.

Differences and similarities in the serotonergic diathesis for suicide attempts and mood disorders: a 22-year longitudinal gene-environment study

To investigate similarities and differences in the serotonergic diathesis for mood disorders and suicide attempts, we conducted a study in a cohort followed longitudinally for 22 years. A total of 1255 members of this cohort, which is representative of the French-speaking population of Quebec, were investigated. Main outcome measures included (1) mood disorders (bipolar disorder and major depression) and suicide attempts by early adulthood; (2) odds ratios and probabilities associated with 143 single nucleotide polymorphisms in 11 serotonergic genes, acting directly or as moderators in gene-environment interactions with childhood sexual or childhood physical abuse (CPA), and in gene-gene interactions; (3) regression coefficients for putative endophenotypes for mood disorders (childhood anxiousness) and suicide attempts (childhood disruptiveness). Five genes showed significant adjusted effects (HTR2A, TPH1, HTR5A, SLC6A4 and HTR1A). Of these, HTR2A variation influenced both suicide attempts and mood disorders, although through different mechanisms. In suicide attempts, HTR2A variants (rs6561333, rs7997012 and rs1885884) were involved through interactions with histories of sexual and physical abuse whereas in mood disorders through one main effect (rs9316235). In terms of phenotype-specific contributions, TPH1 variation (rs10488683) was relevant only in the diathesis for suicide attempts. Three genes contributed exclusively to mood disorders, one through a main effect (HTR5A (rs1657268)) and two through gene-environment interactions with CPA (HTR1A (rs878567) and SLC6A4 (rs3794808)). Childhood anxiousness did not mediate the effects of HTR2A and HTR5A on mood disorders, nor did childhood disruptiveness mediate the effects of TPH1 on suicide attempts. Of the serotonergic genes implicated in mood disorders and suicidal behaviors, four exhibited phenotype-specific effects, suggesting that despite their high concordance and common genetic determinants, suicide attempts and mood disorders may also have partially independent etiological pathways. To identify where these pathways diverge, we need to understand the differential, phenotype-specific gene-environment interactions such as the ones observed in the present study, using suitably powered samples.

Simultaneous analysis of serotonin transporter, tryptophan hydroxylase 1 and 2 gene expression in the ventral prefrontal cortex of suicide victims

Serotonergic signaling abnormalities have been implicated in suicide. Tryptophan hydroxylase (TPH), the rate limiting enzyme of serotonin biosynthesis and the serotonin transporter (SLC6A4), involved in the reuptake of serotonin from the synaptic gap, play major role in serotonergic signaling. In this study, we aimed to compare the levels of expression of these serotonin-related genes between suicide completers and controls and to identify genetic loci involved in their regulation. SLC6A4, TPH1, and TPH2 mRNA levels were measured in the ventral prefrontal cortex (VPFC) of 39 suicide completers and 40 matched controls. To identify the molecular basis of gene expression variation, we performed association studies between cis-acting polymorphisms and SLC6A4, TPH1, and TPH2 transcript levels. Finally, association analyses were carried out between suicide and TPH2 cis-single nucleotide polymorphisms (SNPs) in cohorts of 154 suicide completers and 289 control subjects. Whereas SLC6A4 and TPH1 mRNA expression levels did not differ between suicides and controls, TPH2 levels were found significantly increased (P = 0.003) in suicide completers. We observed that SNP rs10748185 located in the promoter region of TPH2 significantly affect levels of TPH2 mRNA expression. However, we did not find positive association between this eQTL (rs10748185) and suicide. Here, we report the simultaneous analysis of the expression of three serotonin-related genes in the VPFC of suicide victims and controls. This study showed that TPH2 expression levels were increased in the VPFC of suicide victims. Although, we identified a genetic variant that explains variance in TPH2 expression, we did not find evidence associating this cis-regulatory SNP with suicidal behavior.

The genetics of affective disorder and suicide

Suicidal behaviour shows evidence of familial clustering and the twin data on completed suicide suggest moderate heritability. The extent to which the genetics of suicidal behaviour overlaps with the genetics of affective disorders is unclear but there is overwhelming evidence that both bipolar and unipolar disorder are substantially influenced by genes. So far, candidate gene studies of suicidality have provoked much interest, but recently, attention has also turned to candidate gene approaches to suicidal ideation emerging during antidepressant treatment. The advent of genome-wide association studies (GWAS) has had a major impact on studies of affective disorder with some provocative new findings. The GWAS approach is also beginning to be applied in the search for genes that underlie suicidal ideation and behaviour.

Review and meta-analysis of antidepressant pharmacogenetic findings in major depressive disorder

This systematic review summarizes pharmacogenetic studies on antidepressant response and side effects. Out of the 17 genes we reviewed, 8 genes were entered into the meta-analysis (SLC6A4, HTR1A, HTR2A, TPH1, gene encoding the beta-3 subunit, brain-derived neurotrophic factor (BDNF), HTR3A and HTR3B). TPH1 218C/C genotype (7 studies, 754 subjects) was significantly associated with a better response (odds ratio, OR=1.62; P=0.005) with no heterogeneity between ethnicities. A better response was also observed in subjects with the Met variant within the BDNF 66Val/Met polymorphism (4 studies, 490 subjects; OR=1.63, P=0.02). Variable number of tandem repeats polymorphism within intron 2 (STin2) 12/12 genotype showed a trend toward a better response in Asians (STin2: 5 studies, 686 subjects; OR=3.89, P=0.03). As for side effects, pooled ORs of serotonin transporter gene promoter polymorphism (5-HTTLPR) l (9 studies, 2642 subjects) and HTR2A -1438G/G (7 studies, 801 subjects) were associated with a significant risk modulation (OR=0.64, P=0.0005) and (OR=1.91, P=0.0006), respectively. Interestingly, this significance became more robust when analyzed with side effect induced by selective serotonin reuptake inhibitors only (5-HTTLPR: P=0.0001, HTR2A: P<0.0001). No significant result could be observed for the other variants. These results were not corrected for multiple testing in each variant, phenotype and subcategory. This would have required a Bonferroni significance level of P<0.0023. Although some heterogeneity was present across studies, our finding suggests that 5-HTTLPR, STin2, HTR1A, HTR2A, TPH1 and BDNF may modulate antidepressant response.

Do 5HTTLPR and stress interact in risk for depression and suicidality? Item response analyses of a large sample

The reported interaction between the length polymorphism (5HTTLPR) in the serotonin transporter gene (SLC6A4) and stressful life events on depression has led to many attempts to replicate but with inconsistent results. This inconsistency may reflect, in part, small sample size and the unknown contribution of the long allele SNP, rs25531. Using a large twin sample of 3,243 individuals from 2,230 families aged 18-95 years (mean = 32.3, SD = 13.6) we investigate the interaction between 5HTTLPR (subtyped with SNP rs25531) and stressful events on risk of depression and suicidality using both ordinal regressions and item response theory analyses. Participants reported via mailed questionnaire (82% response rate) both stressful events in the preceeding 12 months and symptoms of depression. Stressful events were defined as "personal" (affecting the individual), or "network" (affecting close family or friends). One to 10 years later (mean = 4.2 years), participants completed a comprehensive clinical psychiatric telephone interview (83% response rate) which assessed DSM-IV major depression and ideation of suicidality. Self-reports of depression and an increase in depression/suicidality assessed by clinical interview are significantly associated with prior personal events (P < 0.001) after controlling for age and sex. However, they are inconsistently associated with prior network events (ranging, ns to P < 0.01) and are not significantly associated with any of the genotype main effects (5HTTLPR, 5HTTLPR + rs25531) or interactions (stress x genotype). We find no evidence to support the hypothesis of any 5HTTLPR genotype by stress interaction.

Association analysis between gene variants of the tyrosine hydroxylase and the serotonin transporter in borderline personality disorder

OBJECTIVES

For patients with borderline personality disorder (BPD), we previously reported an independent effect of the catechol-o-methyl-transferase (COMT) low-activity (Met(158)) allele and an interaction with the low-expression allele of the deletion/insertion (short/long or S/L, resp.) polymorphism in the serotonin transporter-linked promoter region (5-HTTLPR). The purpose of the present study was to extend these findings to the tyrosine hydroxylase (TH) Val(81)Met single nucleotide polymorphism (SNP), the 5-HTTLPR S/L polymorphism incorporating the recently described functional A/G SNP within the long allele of the 5-HTTLPR (rs25531) as well as the variable number of tandem repeat (VNTR) polymorphism within intron 2 of the serotonin transporter gene (STin2).

METHODS

In 156 Caucasian BPD patients and 152 healthy controls, we tested for association between BPD and the TH Val(81)Met SNP, the 5-HTTLPR/rs25531 polymorphism, the STin2, the interaction of the TH Val(81)Met SNP with the tri-allelic 5-HTTLPR/rs25531, the interaction of the TH Val(81)Met SNP with STin2.

RESULTS

Between BPD patients and controls, we observed a slight over-representation of the TH Met(81)Met genotype in BPD patients compared to controls, but no statistically significant differences in genotype distribution of the individual markers after adjusting for multiple testing. Logistic regression analysis showed a lack of interaction between the TH Val(81)Met and the 5-HTTLPR/rs25531 as well as between the TH Val(81)Met and the STin2 polymorphism.

CONCLUSIONS

These data do not suggest independent or interactive effects of the TH Val(81)Met, the 5-HTTLPR/rs25531, or the STin2 polymorphisms in BPD.

Association of genetic variants in the neurotrophic receptor-encoding gene NTRK2 and a lifetime history of suicide attempts in depressed patients

CONTEXT

A consistent body of evidence supports a role of reduced neurotrophic signaling in the pathophysiology of major depressive disorder (MDD) and suicidal behavior. Especially in suicide victims, lower postmortem brain messenger RNA and protein levels of neurotrophins and their receptors have been reported.

OBJECTIVE

To determine whether the brain-derived neurotrophic factor (BDNF) gene or its high-affinity receptor gene, receptor tyrosine kinase 2 (NTRK2), confer risk for suicide attempt (SA) and MDD by investigating common genetic variants in these loci.

DESIGN

Eighty-three tagging single-nucleotide polymorphisms (SNPs) covering the genetic variability of these loci in European populations were assessed in a case-control association design.

SETTING

Inpatients and screened control subjects.

PARTICIPANTS

The discovery sample consisted of 394 depressed patients, of whom 113 had SA, and 366 matched healthy control subjects. The replication studies comprised 744 German patients with MDD and 921 African American nonpsychiatric clinic patients, of whom 152 and 119 were positive for SA, respectively.

INTERVENTIONS

Blood or saliva samples were collected from each participant for DNA extraction and genotyping.

MAIN OUTCOME MEASURES

Associations of SNPs in BDNF and NTRK2 with SA and MDD.

RESULTS

Independent SNPs within NTRK2 were associated with SA among depressed patients of the discovery sample that could be confirmed in both the German and African American replication samples. Multilocus interaction analysis revealed that single SNP associations within this locus contribute to the risk of SA in a multiplicative and interactive fashion (P = 4.7 x 10(-7) for a 3-SNP model in the combined German sample). The effect size was 4.5 (95% confidence interval, 2.1-9.8) when patients carrying risk genotypes in all 3 markers were compared with those without any of the 3 risk genotypes.

CONCLUSIONS

Our results suggest that a combination of several independent risk alleles within the NTRK2 locus is associated with SA in depressed patients, further supporting a role of neurotrophins in the pathophysiology of suicide.

Both synthesis and reuptake are critical for replenishing the releasable serotonin pool in Drosophila

The two main sources of serotonin available for release are expected to be newly synthesized serotonin and serotonin recycled after reuptake by the serotonin transporter. However, their relative importance for maintaining release and the time course of regulation are unknown. We studied serotonin signaling in the ventral nerve cord of the larval Drosophila CNS. Fast-scan cyclic voltammetry at implanted microelectrodes was used to detect serotonin elicited by channelrhodopsin2-mediated depolarization. The effects of reuptake were probed by incubating in cocaine, which is selective for the serotonin transporter in Drosophila. p-chlorophenylalanine, an inhibitor of tryptophan hydroxylase2, was used to investigate the effects of synthesis. Stimulations were repeated at various intervals to assess the time course of recovery of the releasable pool. Reuptake is important for the rapid replenishment of the releasable pool, on the 1 min time scale. Synthesis is critical to the longer-term replenishment (10 min) of the releasable pool, especially when reuptake is also inhibited. Concurrent synthesis and reuptake inhibition decreased both serotonin tissue content measured by immunohistochemistry (by 50%) and the initial amount of evoked serotonin (by 65%). Decreases in evoked serotonin are rescued by inhibiting action potential propagation with tetrodotoxin, implicating endogenous activity in the depletion. These results show synthesis is necessary to replenish part of the releasable serotonin pool that is depleted after reuptake inhibition, suggesting that regulation of synthesis may modulate the effects of serotonin reuptake inhibitors.

Nucleotide variation in central nervous system genes among male suicide attempters

Despite marked morbidity and mortality associated with suicidal behavior, accurate identification of individuals at risk remains elusive. The goal of this study is to identify a model based on single nucleotide polymorphisms (SNPs) that discriminates between suicide attempters and non-attempters using data mining strategies. We examined functional SNPs (n = 840) of 312 brain function and development genes using data mining techniques. Two hundred seventy-seven male psychiatric patients aged 18 years or older were recruited at a University hospital psychiatric emergency room or psychiatric short stay unit. The main outcome measure was history of suicide attempts. Three SNPs of three genes (rs10944288, HTR1E; hCV8953491, GABRP; and rs707216, ACTN2) correctly classified 67% of male suicide attempters and non-attempters (0.50 sensitivity, 0.82 specificity, positive likelihood ratio = 2.80, negative likelihood ratio = 1.64). The OR for the combined three SNPs was 4.60 (95% CI: 1.31-16.10). The model's accuracy suggests that in the future similar methodologies may generate simple genetic tests with diagnostic utility in identification of suicide attempters. This strategy may uncover new pathophysiological pathways regarding the neurobiology of suicidal acts.

An association study of the serotonin transporter and receptor genes with the suicidal ideation of major depression in a Chinese Han population

Major depression (MD) is a common psychiatric disorder and one of its most serious symptoms is suicidal ideation. Six polymorphisms in four genes related to the serotonin system, including the HTTLPR and HTTVNTR in the SLC6A4 gene, rs6295 in the HTR1A gene, rs11568817 and rs130058 in the HTR1B gene, and rs6313 in the HTR2A gene, were studied in 420 patients with MD to investigate the relationship between these genes and suicidal ideation in MD. An allele association study revealed a significant relationship between rs11568817 and suicidal ideation, while no association was found for any of the other five polymorphisms. A haplotype association study suggested that the rs11568817-rs130058 haplotype of the HTR1B gene is significantly associated with suicidal ideation in MD. No association was found between suicidal ideation and the combined effect of the genes studied using rs11568817 as a conditional marker. Our work indicated that the HTR1B gene might be involved in the development of suicidal ideation in MD among a Chinese Han population.

Emotional distress in parents of psychotic patients is modified by serotonin transporter gene (5-HTTLPR)--brain-derived neurotrophic factor gene interactions

Caregiving of a family member with psychotic disorder is considered among the most significant stressors and relatives of a sufferer experienced psychological and physical burden that may be the cause of neurotic states. There is growing evidence that sensitivity of individuals to depressogenic effects of stressful factor is moderated by genetic variants of serotonin transporter (SERT) and brain-derived neurotrophic factors (BDNF). We examined the association of the 5-HTTLPR SERT and Val66Met BDNF polymorphisms with signs of depression and anxiety measured with the Minnesota Multiphasic Personality Inventory (MMPI) in 235 unaffected parents of patients with major psychosis and 102 age-matched controls. A significant effect of the SERT-BDNF interaction on Depression and Psychasthenia scales was found in the group of parents, but not in the control group. Carriers of the Val/Val x SS variant scored higher as compared to other allelic combinations. The results obtained revealed that the SERT-BDNF interactions might moderate the level of anxiety and depression caused by caregiving status in parents of psychotic patients.

Genetic predictors of increase in suicidal ideation during antidepressant treatment in the GENDEP project

The aim of this study was to investigate genetic predictors of an increase in suicidal ideation during treatment with a selective serotonin reuptake inhibitor or a tricyclic antidepressant. A total of 796 adult patients with major depressive disorder who were treated with a flexible dosage of escitalopram or nortriptyline in Genome-based Therapeutic Drugs for Depression (GENDEP) were included in the sample and provided data on suicidal ideation. Nine candidate genes involved in neurotrophic, serotonergic, and noradrenergic pathways were selected based on previous association studies with suicidal ideation or behavior. Using a logistic regression model, 123 polymorphisms in these genes were compared between subjects with an increase in suicidal ideation and those without any increase in suicidal ideation. Polymorphisms in BDNF, the gene encoding the brain-derived neurotrophic factor, were significantly associated with an increase in suicidal ideation. The strongest association was observed for rs962369 in BDNF (p=0.0015). Moreover, a significant interaction was found between variants in BDNF and NTRK2, the gene encoding the BNDF receptor (p=0.0003). Among men taking nortriptyline, suicidality was also associated with rs11195419 SNP in the alpha(2A)-adrenergic receptor gene (ADRA2A) (p=0.007). The associations observed with polymorphisms in BDNF suggest the involvement of the neurotrophic system in vulnerability to suicidality. Epistasis between BDNF and NTRK2 suggests that genetic variations in the two genes are involved in the same causal mechanisms leading to suicidality during antidepressant treatment. Among men, genetic variation in noradrenergic signaling may interact with norepinephrine reuptake-inhibiting antidepressants, thereby contributing to suicidality.

The 5-HTTLPR polymorphism modulates the association of serious life events (SLE) and impulsivity in patients with Borderline Personality Disorder

BACKGROUND

Impulsivity belongs to the key features of Borderline Personality Disorder (BPD). It has been linked to altered serotoninergic neurotransmission and, genetically, to an over-representation of the short (S) allele of the serotonin transporter promoter-linked polymorphic region polymorphism (5-HTTLPR). On the other hand, serious life events (SLE) are of major importance in the development of BPD. However, the inter-relations between SLEs, impulsivity, and 5-HTTLPR are not understood.

METHOD

159 BPD patients from Germany were included in this study. Impulsivity was assessed by the Barratt Impulsiveness Scale (BIS). We analysed (1) the effects of SLEs on impulsivity; and (2) modulating effects of the 5-HTTLPR polymorphism on the effects of SLEs on impulsivity.

RESULTS

Regression analyses confirmed a decreasing effect of childhood sexual abuse, the cumulative SLE-related reactions and the impairment by SLEs on BIS sum score. Regarding BIS sum score, all SLEs except for rape were associated with a decrease of impulsivity in SS/SL carriers and an increase of BIS sum score in LL carriers.

CONCLUSIONS

This study analyzing a specific gene x environment interaction in BPD patients suggests an interaction between SLEs and the 5-HTTLPR S/L polymorphism in the development of impulsivity in BPD patients. Clinical and research implications are discussed.

Psychological subtyping finds pathological, impulsive, and 'normal' groups among adolescents who self-harm

BACKGROUND

Research to date suggests that as many as 12-15% of young people engage in self-harm behaviour; however, the current understanding of the psychological basis of adolescent self-harm is limited. The objective was to determine whether adolescents who self-harm are a psychologically homogenous group. It was hypothesised that psychological subtypes would exist and these groups would report different rates of self-harm.

METHOD

Nine hundred and forty-four school students aged 11 to 19 and 166 first-year psychology students aged 21 or younger completed a self-report questionnaire. Participants were aged 11 to 21 (mean = 15.4, SD = 2.1). Sixty-two percent of the sample were female (n = 692). Students were allocated to psychologically distinct groups. Rates of self-harm were compared for the psychological subtypes of self-harmers.

RESULTS

Two hundred and thirty-four participants reported lifetime self-harm (21.1%; 95% CI 19-23%) and 78 reported recent self-harm (7.0%; 95% CI 6.7-7.3%). The present study identified three psychologically quite distinct groups of adolescents within those who reported self-harm - a psychologically pathological group, a psychologically 'normal' group, and an impulsive group. The pathological group reported the highest rate of recent self-harm (50.9%); the psychologically 'normal' and impulsive groups reported similar rates of self-harm (28.7% and 24.6%, respectively).

CONCLUSIONS

Adolescents who self-harm are not a psychologically homogenous group. One pathological subtype of self-harmers appears to most closely reflect a number of the psychological and social factors previously associated with self-harm. However, a large proportion of the sample was allocated the psychologically 'normal' subtype. This finding highlights the importance of psychological screening of adolescents presenting for treatment for self-harm as subtypes of self-harmers may require disparate strategies for intervention. Further research is required in order to identify appropriate treatment strategies for each subtype.

Interaction between gene variants of the serotonin transporter promoter region (5-HTTLPR) and catechol O-methyltransferase (COMT) in borderline personality disorder

Borderline personality disorder (BPD) is characterized by a heterogeneous symptomatology with instability in impulse control, interpersonal relationships and self-image. BPD patients display repeated self-injury, chronic suicidal tendencies and emotional dysregulation, mainly dysregulation of negative affect. In its etiology, genetic and environmental factors have been suggested. Recently, an investigation in male healthy volunteers found gene-gene effects of the catechol-O-methyl-transferase (COMT) low-activity (Met(158)) and the low-expression allele of the deletion/insertion (short/long or S/L, respectively) polymorphism in the serotonin transporter-linked promoter region (5-HTTLPR) on the central processing of aversive stimuli. The purpose of the present study was to test for association between BPD and the COMT Val(158)Met single nucleotide polymorphism (SNP), the 5-HTTLPR S/L variant and the interaction of these two gene variants. One hundred sixty one well-defined Caucasian BPD patients and 156 healthy controls were recruited from central Germany. In BPD patients, the genotype COMT Met(158)Met was over-represented compared to healthy controls (P = 0.0085; adjusted P = 0.034). We observed no differences in 5-HTTLPR genotypes between BPD and controls (P = 0.286). Additionally, the COMT Met(158)Met genotype was significantly over-represented in BPD patients carrying at least one 5-HTTLPR S allele (P = 0.0007; adjusted P = 0.028). Logistic regression analysis confirmed an interaction of the COMT Met(158) and the 5-HTTLPR S allele (P = 0.001). These data suggest an involvement of altered dopaminergic and/or noradrenergic neurotransmission as well as an interactive effect of COMT and 5-HTTLPR gene variants in the etiology of BPD, and underline the usefulness of analyses of gene-gene effects in diseases of complex inheritance with multiple genes involved.

Imaging elevated brain arachidonic acid signaling in unanesthetized serotonin transporter (5-HTT)-deficient mice

Certain polymorphisms reduce serotonin (5-HT) reuptake transporter (5-HTT) function and increase susceptibility to psychiatric disorders. Heterozygous (5-HTT(+/-))-deficient mice, models for humans with these polymorphisms, have elevated brain 5-HT concentrations and behavioral abnormalities. As postsynaptic 5-HT(2A/2C) receptors are coupled to cytosolic phospholipase A(2) (cPLA(2)), which releases arachidonic acid (AA) from membrane phospholipid, 5-HTT-deficient mice may have altered brain AA signaling and metabolism. To test this hypothesis, signaling was imaged as an AA incorporation coefficient k(*) in unanesthetized homozygous knockout (5-HTT(-/-)), 5-HTT(+/-) and wild-type (5-HTT(+/+)), mice following saline (baseline) or 1.5 mg/kg s.c. DOI, a partial 5-HT(2A/2C) receptor agonist. Enzyme activities, metabolite concentrations, and head-twitch responses to DOI were also measured. Baseline k(*) was widely elevated by 20-70% in brains of 5-HTT(+/-) and 5-HTT(-/-) compared to 5-HTT(+/+) mice. DOI increased k(*) in 5-HTT(+/+) mice, but decreased k(*) in 5-HTT-deficient mice. Brain cPLA(2) activity was elevated in 5-HTT-deficient mice; cyclooxygenase activity and prostaglandin E(2) and F(2alpha) and thromboxane B(2) concentrations were reduced. Head-twitch responses to DOI, although robust in 5-HTT(+/+) and 5-HTT(+/-) mice, were markedly fewer in 5-HTT(-/-) mice. Pretreatment with para-chlorophenylalanine, a 5-HT synthesis inhibitor, restored head twitches in 5-HTT(-/-) mice to levels in 5-HTT(+/+) mice. We propose that increased baseline values of k(*) in 5-HTT-deficient mice reflect tonic cPLA(2) stimulation through 5-HT(2A/2C) receptors occupied by excess 5-HT, and that reduced k(*) and head-twitch responses to DOI reflected displacement of receptor-bound 5-HT by DOI with a lower affinity. Increased baseline AA signaling in humans having polymorphisms with reduced 5-HTT function might be identified using positron emission tomography.

Association between Val66Met brain-derived neurotrophic factor (BDNF) gene polymorphism and post-treatment relapse in alcohol dependence

BACKGROUND

The purpose of this study was to examine relationships between genetic markers of central serotonin (5-HT) and dopamine function, and risk for post-treatment relapse, in a sample of alcohol-dependent patients.

METHODS

The study included 154 patients from addiction treatment programs in Poland, who met DSM-IV criteria for alcohol dependence. After assessing demographics, severity of alcohol use, suicidality, impulsivity, depression, hopelessness, and severity of alcohol use at baseline, patients were followed for approximately 1 year to evaluate treatment outcomes. Genetic polymorphisms in several genes (TPH2, SLC6A4, HTR1A, HTR2A, COMT, and BDNF) were tested as predictors of relapse (defined as any drinking during follow-up) while controlling for baseline measures.

RESULTS

Of 154 eligible patients, 123 (80%) completed follow-up and 48% (n = 59) of these individuals relapsed. Patients with the Val allele in the Val66Met BDNF polymorphism and the Met allele in the Val158Met COMT polymorphism were more likely to relapse. Only the BDNF Val/Val genotype predicted post-treatment relapse [odds ratio (OR) = 2.62; p = 0.019], and time to relapse (OR = 2.57; p = 0.002), after adjusting for baseline measures and other significant genetic markers. When the analysis was restricted to patients with a family history of alcohol dependence (n = 73), the associations between the BDNF Val/Val genotype and relapse (OR = 5.76, p = 0.0045) and time to relapse (hazard ratio = 4.93, p = 0.001) were even stronger.

CONCLUSIONS

The Val66Met BDNF gene polymorphism was associated with a higher risk and earlier occurrence of relapse among patients treated for alcohol dependence. The study suggests a relationship between genetic markers and treatment outcomes in alcohol dependence. Because a large number of statistical tests were conducted for this study and the literature on genetics and relapse is so novel, the results should be considered as hypothesis generating and need to be replicated in independent studies.

Towards a genetically validated new affective temperament scale: a delineation of the temperament phenotype of 5-HTTLPR using the TEMPS-A

BACKGROUND

Although it has been described that affective temperaments are associated with the 5-HTTLPR, less attention was paid to the association between this polymorphism and subscales and items related to each affective temperament. The aim of our study was to investigate the association of affective temperament subscales and individual items with the s allele of the 5-HTTLPR.

METHOD

138 psychiatrically healthy women completed the TEMPS-A questionnaire and were genotyped for 5-HTTLPR. Scores of subjects on the temperament scales, subscales and items in the three genotype and the two phenotype groups were compared using ANOVA. We selected items with significantly different mean scores between the three genotype groups and the two phenotype groups separately and performed item analysis.

RESULTS

Subjects in the different 5-HTTLPR genotype and phenotype groups have significantly different score on scales measuring depressive, cyclothymic, irritable and anxious temperaments, and several subscales composing these temperamental scales. Subjects in the three genotype groups scored significantly different on 11 items, 8 of these remained in a derived genotype scale after item analysis. Subjects in the two phenotype groups had significantly different scores on 12 items, 9 of them were retained in a derived phenotype scale after item analysis.

LIMITATIONS

Our sample was relatively small and included only women.

CONCLUSIONS

Our data provide support for the association of affective temperaments with the s allele. Although the cyclothymic temperament shows the strongest association, all temperaments within the depressive superfactor have a similar share in this association. The newly derived 5-HTTLPR Phenotype Scale shows strong association with 5-HTTLPR genotype and phenotype, therefore this scale should be further investigated in relation to psychiatric disorders, as well as psychological traits and temperaments.

Association of serotonin transporter gene polymorphisms with poststroke depression

CONTEXT

Polymorphisms of the serotonin transporter gene (SERT) have been associated with mental illness. In people with long-term medical conditions, variants of the 5-HTTLPR and STin2 VNTR polymorphisms of SERT have been shown to confer a heightened vulnerability to comorbid depression.

OBJECTIVE

To determine whether the 5-HTTLPR, STin2 VNTR, and rs25531 polymorphisms of SERT are associated with poststroke depression (PSD) in stroke survivors.

DESIGN

A case-control study in which stroke survivors were screened for depressive symptoms and assigned to either a depressed group or a nondepressed group.

SETTING

Outpatient clinic.

PARTICIPANTS

Seventy-five stroke survivors with PSD and 75 nondepressed stroke survivors.

INTERVENTIONS

Blood or saliva samples were collected from each participant for DNA extraction and genotyping.

MAIN OUTCOME MEASURES

The associations between the 5-HTTLPR, STin2 VNTR, and rs25531 polymorphisms and PSD.

RESULTS

Individuals with the 5-HTTLPR s/s genotype had 3-fold higher odds of PSD compared with l/l or l/xl genotype carriers (odds ratio, 3.1; 95% confidence interval, 1.2-8.3). Participants with the STin2 9/12 or 12/12 genotype had 4-fold higher odds of PSD compared with STin2 10/10 genotype carriers (odds ratio, 4.1; 95% confidence interval, 1.2-13.6). An association of rs25531 with PSD was not shown.

CONCLUSIONS

The 5-HTTLPR and the STin2 VNTR, but not the rs25531, polymorphisms of SERT are associated with PSD in stroke survivors. This gives further evidence of a role of SERT polymorphisms in mediating resilience to biopsychosocial stress.

Association between the A-1438G polymorphism of the serotonin 2A receptor gene and nonimpulsive suicide attempts

OBJECTIVE

To investigate the association between four serotonergic polymorphisms [A-1438G (rs6311) and T102C (rs6313) of the serotonin 2A receptor gene, and STin2 VNTR and 5-HTTLPR of the SLC6A4 gene] and suicidal behavior.

PARTICIPANTS AND METHODS

One hundred and ninety-three suicide attempters (SA) and 420 unrelated healthy controls from Asturias (Northern Spain) were genotyped using standard methods.

RESULTS

A-1438G and T102C polymorphisms were in complete linkage disequilibrium in our population. Genotype and allele distributions showed no differences between SA and control participants. In nonimpulsive suicide attempts, however, we found an excess of the -1438A allele as compared with impulsive suicide attempts and the control group [chi(2)=11.92, corrected P=0.021]. No other differences were found with regard to the impulsivity of the attempt. An excess of short allele carriers were found in the group of SA with high clinical lethality as compared with the low-lethality group [chi(1)=4.93, P=0.026, not significant after Bonferroni correction]. The haplotype analysis showed no association between suicide attempt and haplotype distribution [likelihood ratio test (5)=4.40, P=0.493].

CONCLUSION

Our findings suggest that the -1438A allele may predispose for nonimpulsive suicidal behavior.