Association of the serotonin transporter promoter polymorphism with suicidal behavior

5-HTTLPR-brain-derived neurotrophic factor (BDNF) gene interactions and early adverse life events effect on impulsivity in suicide attempters

OBJECTIVES

An expanding body of research suggests that childhood adverse experiences can lead to different negative health outcomes, including attempted suicide. Serotonergic genes such as the promoter region of the serotonin transporter gene (5-HTTLPR) have been associated both with impulsivity in suicide attempts and reactivity to environmental stress exposure. BDNF gene may play an epigenetic role.

METHODS

We studied the influence of childhood stressful events and 5-HTTLPR genotype on impulsivity measured by Barratt Impulsivity Scale (BIS-10) in a multicentre sample of 1,655 suicide attempters (69.4% women, 30.6% men; mean age 40.13 years). A co-dominant additive genetic model was used for the statistical analyses. Interaction between 5-HTTLPR genotype and early trauma exposure was tested using moderated and multiple regression techniques. Interaction plots were used to explore BDNF genotype modulation.

RESULTS

Mildly higher impulsivity scores were found in men with SS compared with SL or LL genotypes, and men with childhood emotional and physical abuse. Interaction analyses showed that combination of 5-HTTLPR-SS genotype and early trauma exposure increase impulsivity scores independently. Impulsivity scores were not affected by the modulation of BDNF genes.

CONCLUSIONS

Childhood trauma and 5-HTTLPR genotype seem to be independently involved in suicide attempts, sharing a common pathway of increasing impulsivity.

The influence of the serotonin transporter gene 5-HTTLPR polymorphism on suicidal behaviors: a meta-analysis

Suicidal Behavior (SB) is the second leading cause of death among youths worldwide and the tenth among all age groups. Inherited genetic differences have a role in suicidality with heritability ranging from 30 to 55%. The SLC6A4 5-HTTLPR gene variant has been largely investigated for association with SB, with controversial results. In this work, we sought to determine whether the results of previous meta-analyses were confirmed or modified subsequent to the inclusion of more recent literature data. An electronic literature search was performed to identify relevant studies published until July 2018. Data were analysed through RevMan v5.3. Subgroup and sensitivity meta-analyses were performed considering different SB sub-phenotypes, ethnicity, gender and psychiatric diagnostic categories. Our literature search yielded 1186 articles; among these, we identified 45 pertinent case-control studies (15,341 subjects). No association was found between low-expressing alleles or genotypes (S + L_G alleles or S' carrier genotypes) and SB in the primary analyses. However, low-expressing alleles (S + L_G) were associated with an increased risk of Violent Suicide Attempt (OR = 1.44, C.I. 1.17-1.78, p = .0007). An effect of the same alleles on SB was found in a subpopulation of substance abusers, but this result was not confirmed after the exclusion of healthy subjects from the control group. The other sensitivity meta-analyses did not show any significant effect. Our findings contribute to clarify the conflicting previous evidence by suggesting an association between the 5-HTTLPR and Violent SB. Nonetheless, many other modulators, including environmental factors and epigenetic mechanisms may act to further increase the level of complexity.

Serotonin transporter gene polymorphism as a predictor of short-term risk of suicide reattempts

Objective:

The serotonin-transporter-linked polymorphic region (5-HTTLPR) polymorphisms are associated with suicidal behavior; however, prospective studies are scarce. Herein we aim to determine if 5-HTTLPR polymorphisms predict risk of short-term suicide reattempt in a high-risk suicidal sample. We also explore possible mediators or moderators of this relationship.

Methods:

A multicenter prospective cohort study was designed to compare data obtained form 136 patients admitted to the emergency department for current suicidal ideation or a recent suicide attempt. Subjects were clinically evaluated, genotyped, and monitored for a new suicide attempt for 6 months.

Results:

At 6 months of follow up, 21% of the subjects had a new suicide attempt. The frequency of L-allele and L-carrier was higher in reattempters when compared with non-reattempters (55.8% vs. 35.4%, p = 0.01 and 76.9% vs. 54.2%, p = 0.04, respectively). Reattempters also differ from non-reattempters patients with respect to age, history of previous suicide attempts, and age of onset of suicidal behavior. The logistic regression model showed that L-carriers had an odds ratio of 2.8 (95% CI: 1.0–7.6) for reattempts when compared to SS genotype. The adjusted model indicates that this association is not mediated or moderated by impulsivity.

Conclusion:

The 5-HTTLPR polymorphisms predicted short-term risk of suicidal reattempt independently of age and sex. L-carriers have almost three times more risk of relapse when compared with SS carriers.

A review of the serotonin transporter and prenatal cortisol in the development of autism spectrum disorders

The diagnosis of autism spectrum disorder (ASD) during early childhood has a profound effect not only on young children but on their families. Aside from the physical and behavioural issues that need to be dealt with, there are significant emotional and financial costs associated with living with someone diagnosed with ASD. Understanding how autism occurs will assist in preparing families to deal with ASD, if not preventing or lessening its occurrence.

Serotonin plays a vital role in the development of the brain during the prenatal and postnatal periods, yet very little is known about the serotonergic systems that affect children with ASD. This review seeks to provide an understanding of the biochemistry and physiological actions of serotonin and its termination of action through the serotonin reuptake transporter (SERT). Epidemiological studies investigating prenatal conditions that can increase the risk of ASD describe a number of factors which elevate plasma cortisol levels causing such symptoms during pregnancy such as hypertension, gestational diabetes and depression. Because cortisol plays an important role in driving dysregulation of serotonergic signalling through elevating SERT production in the developing brain, it is also necessary to investigate the physiological functions of cortisol, its action during gestation and metabolic syndromes.

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.

Molecular medicine: a path towards a personalized medicine

Psychiatric disorders are among the most common human illnesses; still, the molecular and cellular mechanisms underlying their complex pathophysiology remain to be fully elucidated. Over the past 10 years, our group has been investigating the molecular abnormalities in major signaling pathways involved in psychiatric disorders. Recent evidences obtained by the Instituto Nacional de Ciência e Tecnologia de Medicina Molecular (National Institute of Science and Technology - Molecular Medicine, INCT-MM) and others using behavioral analysis of animal models provided valuable insights into the underlying molecular alterations responsible for many complex neuropsychiatric disorders, suggesting that "defects" in critical intracellular signaling pathways have an important role in regulating neurodevelopment, as well as in pathophysiology and treatment efficacy. Resources from the INCT have allowed us to start doing research in the field of molecular imaging. Molecular imaging is a research discipline that visualizes, characterizes, and quantifies the biologic processes taking place at cellular and molecular levels in humans and other living systems through the results of image within the reality of the physiological environment. In order to recognize targets, molecular imaging applies specific instruments (e.g., PET) that enable visualization and quantification in space and in real-time of signals from molecular imaging agents. The objective of molecular medicine is to individualize treatment and improve patient care. Thus, molecular imaging is an additional tool to achieve our ultimate goal.

Modulation of human serotonin transporter expression by 5-HTTLPR in colon cells

Serotonin (5-HT) is a monoamine neurotransmitter and plays important roles in several of the human body's systems. Known as a primary target for psychoactive drug development, the 5-HT transporter (5-HTT, SERT) plays a critical role in the regulation of serotonergic function by reuptaking 5-HT. The allelic variation of 5-HTT expression is caused by functional gene promoter polymorphism with two principal variant alleles, 5-HTT gene-linked polymorphic region (5-HTTLPR). It has been demonstrated that 5-HTTLPR is associated with numerous neuropsychiatric disorders. The functional roles of 5-HTTLPR have been reported in human choriocarcinoma (JAR), lymphoblast and raphe cells. To date, the significance of 5-HTTLPR in gastrointestinal tract-derived cells has never been elucidated. Thus, the impact of 5-HTTLPR on 5-HTT transcription was studied in SW480 human colon carcinoma cells, which were shown to express 5-HTT. We found 42-bp fragment in long (L) allele as compared to short (S) allele, and this allelic difference resulted in 2-fold higher transcriptional efficiency of L allele (P < 0.05) as demonstrated using a functional reporter gene assay. Nevertheless, the transcriptional effect of estrogen and glucocorticoid on 5-HTT expression via 5-HTTLPR was not found in this cell line. Our study was the first to demonstrate the molecular role of this allelic variation in gastrointestinal tract cells.

The 5-HTTLPR polymorphism, impulsivity and suicide behavior in euthymic bipolar patients

BACKGROUND

Suicide behavior is very frequent in Bipolar Disorder (BD) and they are both closely associated with impulsivity. Furthermore they are, impulsivity, BD and suicide behavior, associated with serotonergic function, at least partially, under genetic determinism and somewhat associated with the serotonin transporter gene polymorphism, the 5-HTTLPR. We aimed to assess different impulsivity components in BD sub-grouped by suicidal attempt and healthy controls. We hypothesized that the non-planning/cognitive impulsivity, could be more closely associated with suicidal behavior. We further associated 5-HTTLPR genotypes with neuropsychological results to test the hypothesis that this polymorphism is associated with cognitive impulsivity.

METHOD

We assessed 95 euthymic bipolar patients sub-grouped by suicidal attempt history in comparison with 94 healthy controls. All subjects underwent a laboratory assessment of impulsivity (Continuous Performance Test and Iowa Gambling Test). Furthermore the genotyping of 5-HTTLPR was performed in all subjects.

RESULTS

We found that bipolar patients are more impulsive than healthy controls in all impulsivity dimensions we studied. Furthermore bipolar patients with a suicide attempt history have a greater cognitive impulsivity when compared to both bipolar patients without such a history as well when compared to healthy controls. No association was found between 5-HTTLPR genotypes and neuropsychological measures of impulsive behavior.

LIMITATIONS

The sample studied can be considered small and a potentially confounding variable - medication status - was not controlled.

CONCLUSION

A lifetime suicide attempt seems associated with cognitive impulsivity independently of the socio-demographic and clinical variables studied as well with 5-HTTLPR genotype. Further studies in larger samples are necessary.

The role of BDNF genetic polymorphisms in bipolar disorder with psychiatric comorbidities

BACKGROUND

Bipolar disorder (BD) is a complex disorder where genetic factors play a major role in its etiology. Probably, no other axis I diagnosis has a co-morbidity prevalence as high as BD. Since BDNF is involved in different ways in various psychiatric disorders we hypothesized that its genetic polymorphisms could be associated with the co-morbidity phenomenon in BD.

METHODS

We studied 320 subjects (160 BD patients and 160 healthy controls). Genotyping was performed using made-to-order TaqMan genotyping assays (rs4923463, rs6265, rs2049045, and rs7103411). Statistical analyses were performed using UNPHASED version 3.0.12 and Haploview 4.1.

RESULTS

No genotypic, allelic or haplotype differences were found between bipolar patients and healthy controls. Concerning exclusively the rs4923463 (G/G) there was a significant association with alcoholism (p=0.009), smoking (p=0.006) and violent suicide attempt (p=0.03). We further found that the G-G haplotype (rs4923463-rs2049045) (adjusted p=0.029) and the G-T haplotype (rs4923463-rs7103411) (adjusted p=0.029) were significantly more frequent in the group with alcoholism co-morbidity when compared with the group without this co-morbidity.

LIMITATIONS

Sample size and retrospective assessment of suicide behavior and psychiatric comorbidities.

CONCLUSIONS

The results obtained in our study indicate that BDNF variants may confer susceptibility to additional psychiatric diagnosis in BD.

P2RX7 gene is associated consistently with mood disorders and predicts clinical outcome in three clinical cohorts

We investigated the effect of nine candidate genes on risk for mood disorders, hypothesizing that predisposing gene variants not only elevate the risk for mood disorders but also result in clinically significant differences in the clinical course of mood disorders. We genotyped 178 DSM-IV bipolar I and II and 272 major depressive disorder patients from three independent clinical cohorts carefully diagnosed with semistructured interviews and prospectively followed up with life charts for a median of 60 (range 6-83) months. Healthy control subjects (n = 1322) were obtained from the population-based national Health 2000 Study. We analyzed 62 genotyped variants within the selected genes (BDNF, NTRK2, SLC6A4, TPH2, P2RX7, DAOA, COMT, DISC1, and MAOA) against the presence of mood disorder, and in post-hoc analyses, specifically against bipolar disorder or major depressive disorder. Estimates for time ill were based on life charts. The P2RX7 gene variants rs208294 and rs2230912 significantly elevated the risk for a familial mood disorder (OR = 1.35, P = 0.0013, permuted P = 0.06, and OR = 1.44, P = 0.0031, permuted P = 0.17, respectively). The results were consistent in all three cohorts. The same risk alleles predicted more time ill in all cohorts (OR 1.3, 95% CI 1.1-1.6, P = 0.0069 and OR 1.7, 95% CI 1.3-2.3, P = 0.0002 with rs208294 and rs2230912, respectively), so that homozygous carriers spent 12 and 24% more time ill. P2RX7 and its risk alleles predisposed to mood disorders consistently in three independent clinical cohorts. The same risk alleles resulted in clinically significant differences in outcome of patients with major depressive and bipolar disorder.

The Problematic Label of Suicide Gesture: Alternatives for Clinical Research and Practice

Historically, certain terms used to describe psychopathology have evolved over time due to changing social and political contexts. This paper explores the importance of a clear and consistent language for characterizing suicide-related behaviors with a particular focus on the commonly used label "suicide gesture." The historical and contemporary uses of the term are explored, and clinical, research, and training implications are discussed. Clinicians and researchers are strongly encouraged to consider discontinuing the use of the term suicide gesture in light of its associated dismissive connotations and inconsistent application in clinical practice and research. In lieu of the term suicide gesture, recommendations are made regarding an increased emphasis by clinicians and researchers on more precise descriptions of suicidal behaviors and the functional assessment of suicide-related behaviors.

A review of psychiatric genetics research in the Brazilian population

OBJECTIVE AND METHOD: A large increase in the number of Brazilian studies on psychiatric genetics has been observed in the 1970's since the first publications conducted by a group of researchers in Brazil. Here we reviewed the literature and evaluated the advantages and difficulties of psychiatric genetic studies in the Brazilian population. CONCLUSION: The Brazilian population is one of the most heterogeneous populations in the world, formed mainly by the admixture between European, African and Native American populations. Although the admixture process is not a particularity of the Brazilian population, much of the history and social development in Brazil underlies the ethnic melting pot we observe nowadays. Such ethnical heterogeneity of the Brazilian population obviously brings some problems when performing genetic studies. However, the Brazilian population offers a number of particular characteristics that are of major interest when genetic studies are carried out, such as the presence of isolated populations. Thus, differences in the genetic profile and in the exposure to environmental risks may result in different interactions and pathways to psychopathology.

The genetics of suicide: a critical review of molecular studies

Genetic epidemiology research has shown that genes contribute to suicide risk. Unfortunately, the first 30 years of candidate-based association studies have provided little information about the specific genetic contributors. This article reviews genetic association studies of suicidal phenotypes published to date. Possible theoretical, methodological, and operational challenges accounting for the modest success of association studies in the field are also discussed. The authors conclude that future research may benefit from using a more systematic and comprehensive selection of candidate genes and variants, examining gene-environment and gene-gene interactions, and investigating higher-order moderators.

Analysis of association of clinical correlates and 5-HTTLPR polymorphism with suicidal behavior among Chinese methamphetamine abusers

Substance use disorders are familial, and genetic factors explain a substantial degree of their familial aggregation. Methamphetamine (MAP) abusers are commonly noted as having psychosis, depression and suicidal behavior. The goals of the present study were (i) to investigate relations of clinical correlates, such as gender, drug use behavior, psychiatric comorbidity and psychiatry family history, with suicidal behavior among Chinese MAP abusers; and (ii) to investigate whether there is an association between a polymorphism in the promotor region of the serotonin transporter gene (5-HTTLPR) and suicidal behavior among Chinese MAP abusers. A total of 439 MAP abusers from a hospital and detention center in Taipei were interviewed with the Diagnostic Interview for Genetic Study and the Family Interview for Genetic Study. The 5-HTTLPR polymorphism was compared between 94 MAP abusers with suicide attempts and 294 MAP abusers without suicide attempts, for whom DNA data were available. The results of the present study indicate that among MAP abusers in Taiwan, suicide attempts were significantly related to female gender, history of MAP-induced psychotic disorder, history of MAP-induced depressive disorder, and family history of psychotic disorders. Among suicide attempters, the attempters with moderate to severe lethality used higher MAP doses than those with minimal to mild lethality. In the present sample the triallelic 5-HTTLPR polymorphism (S, L(G), L(A)) was not associated with MAP-induced depressive disorder, MAP-induced psychotic disorder or suicidal behavior, but studies with larger sample sizes are warranted before excluding the role of the 5-HTTLPR polymorphisms in suicidal behavior among MAP abusers.

Association study of T102C 5-HT(2A) polymorphism in schizophrenic patients: diagnosis, psychopathology, and suicidal behavior

The objective of this study was to examine the association between the serotonin (5-HT)2A gene polymorphism (102T/C) and suicidal behavior in schizophrenic inpatients. We studied 129 subjects who met the diagnostic criteria for schizophrenia according to a structured clinical interview (MINI-PLUS). Patients underwent a semistructured interview to assess suicide attempt history and its characteristics. In addition, at least one close relative of the patient was interviewed to assess proband and family suicidal behavior. Healthy controls were students and hospital staff members free of psychiatric and medical illness. Genotypes were determined after polymerase chain reaction amplification of the region of 5-HT(2A)/T102C containing the polymorphic site and digestion with the restriction enzyme Hpall. We found no association between suicidal attempt history and suicide attempt characteristics and genotypic or allele frequencies. Suicidal behavior was also not associated with demographic or psychopathological characteristics. These results suggest that the 5-HT(2A) gene polymorphism (102T/C) is not involved in genetic susceptibility to suicidal behavior, but further studies in a larger sample are needed.

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

Suicidal behavior, which ranks among the top 10 causes of death worldwide, is an important public-health problem and a psychiatric disorder, which has been the subject of considerable study. Studies have shown association between the serotonin transporter (5-HTT) gene and suicidal behavior, although a proportion of alternative studies have produced contrary results both in terms of positive and negative findings, possibly reflecting inadequate statistical power and the use of different populations. Using the cumulative data from recent years in both European and, more particularly, Asian populations, this updated meta-analysis seeks to examine whether the aggregate data provide evidence of statistical significance, and to clarify the contradictory findings suggested by previous studies. It covers all published studies using multiple research methods up to January 2006. Compared with a previous meta-analysis, which found no association between the 5-HTTLPR polymorphism and suicidal behavior (P=0.38), the current results (39 studies) suggest a significant association with a P-value of 0.0068 (overall odds ratio=0.88 (0.8,0.97)), and supports the involvement of the brain 5-HTT in the pathogenesis of suicidal behavior.

Genetics of suicide

The concept that genetic factors contribute to the complex trait of suicidal behaviour has stimulated much work aimed at identifying susceptibility genes. So far molecular genetic studies focused on the serotonergic pathway as the intent to die and the lethality of suicide acts were related to the serotonergic system. Two genes have so far emerged as being involved in the vulnerability for suicidality: first, the intronic polymorphisms (A218C or A779C) of the tryptophan hydroxylase 1 (TPH1) gene, which was suggested as a quantitative risk factor for suicidal behaviour; second, the insertion/deletion polymorphism of the serotonin transporter gene (5-HTTLPR), which does not seem to be involved in general suicidal behaviour, but in violent and repeated suicide attempts. The data have further shown that the MAOA gene, which is consistently associated with impulsive-aggressive personality traits, is not related to suicide but might induce violent methods in subjects with other suicide risk factors. Predominantly negative were the findings with any type of the serotonin receptors and inconsistent with catecholamine-synthesizing and -metabolizing enzymes or with the dopaminergic receptors. This paper reviews the status of current knowledge in this area, points to the weakness of the investigations and presents new approaches beyond the serotonergic system.

The serotonin transporter promoter polymorphism and suicide

Serotonergic dysfunction has been implicated in mood disorders and in the pathophysiology of suicidality. A functional polymorphism (a 44-base pair insertion (L)/deletion (S)) in the promoter of the gene encoding the serotonin transporter (5-HTTLPR), associated with mood disorders, has been inconsistently associated with suicidality. To add to this debate, we designed a case-control study involving 62 suicide victims and 72 controls matched for age, gender and ethnicity. All subjects underwent forensic investigation. No association could be detected between the 5-HTTLPR polymorphism and suicide. This result is consistent with the proposal that different genes are involved in hopelessness and suicidal behavior or in depressive illness.

STin2 variant and family history of suicide as significant predictors of suicide completion in major depression

BACKGROUND

Suicide is the most serious outcome of major depression, yet not all depressed patients will commit suicide. Genes, along with other factors, might account for this difference. Serotonergic alterations have been observed in suicide and depression and impulsive-aggressive behaviors. Therefore, we aimed to identify predictors of suicide, considering genetic variation at the serotonin transporter (5-HTT) gene.

METHODS

We investigated the 5-HTT gene-linked polymorphic region (5-HTTLPR) and intron 2 (STin2) variants of this gene and their relationship to behavioral and clinical risk factors for suicide in a sample of depressed suicides (n =106) and depressed control subjects (n =152), diagnosed by means of proxy-based interviews.

RESULTS

We found a significant association of suicide completion with having at least one copy of the STin2 10 allele [chi(2)(1) = 10.833, p = .002]. No differences were found for the 5-HTTLPR variable number of tandem repeats. After controlling for behavioral and clinical risk factors for suicide, the STin2 variant remained a significant predictor of suicide in major depression when jointly considered with a family history of suicide (odds ratio 5.560, 95% confidence interval 1.057-29.247).

CONCLUSIONS

The STin2 locus might account, at least in part, for the observed familial aggregation of suicidal behavior. These results should be further explored in families where clustering of suicidal behavior is observed.

Familial suicide behaviour: association with probands suicide attempt characteristics and 5-HTTLPR polymorphism

OBJECTIVE

There is compelling evidence that a serotonergic dysfunction may play a major role in suicide behaviour and it has also been demonstrated that suicide is, at least partially, genetically determined. Thus, the serotonin-related genes are the major candidates. Previously a functional polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) was identified and the presence of the short allele (S) was found to be associated with a lower level of expression of the gene and lower levels of 5-HT uptake when compared with the long allele (L). The purpose of this study was to evaluate the association between family suicide behaviour history and probands' suicide attempt (SA) history, SA characteristics and 5-HTTLPR genotype.

METHOD

We genotyped 237 probands (major depressed or schizophrenic patients) and used a semistructured interview to determine probands' SA characteristics and first- and second-degree family suicidal behaviour.

RESULTS

An association between suicidal family history and proband's SA but not with SA characteristics and probands genotype was found.

CONCLUSION

Our results suggest that multiple biological and environmental factors underlie familial transmission of suicidal behaviour.

Association between serotonin transporter gene promoter polymorphism and suicide: results of a meta-analysis

BACKGROUND

There is strong evidence supporting a role for serotonin system dysfunction in the pathology of suicidal behavior. Many studies have examined the association between a functional polymorphism of the serotonin transporter gene promoter (5-HTTLPR) and suicide but have yielded inconsistent results. Our goal here, by analyzing the cumulative data from primary literature, was to determine conclusively whether there is an association.

METHODS

Three meta-analyses were performed. One compared the 5-HTTLPR polymorphism between suicidal subjects and normal control subjects; another compared suicide attempters with nonattempters of the same psychiatric diagnoses; the last one compared either violent or nonviolent suicidal subjects with normal control subjects.

RESULTS

We found no association between 5-HTTLPR polymorphism and suicidal behavior (p =.379). When we compared subjects with the same psychiatric diagnoses, the genotypes carrying the s allele were significantly more frequent in suicide attempters than in nonattempters (p =.004). In addition, the s allele was associated with violent suicide (p =.0001) but not with nonviolent suicide (p = 1.00).

CONCLUSIONS

Our results provide significant evidence supporting the association of the s allele of 5-HTTLPR polymorphism with suicidal behavior in the psychiatric population, also with violent suicide. These support a role for decreased serotonin transporter function in the vulnerability to suicide in a select population.