Serotonin 2A receptor gene is associated with personality traits, but not to disorder, in patients with borderline personality disorder

Integrating Psychosocial Risks With Emerging Evidence for Borderline Personality Disorders in Adolescence: An Update for Clinicians

Borderline personality disorder (BPD) has seen significant advances in the knowledge of its developmental phenomenology during late childhood and adolescence. Various genetic, neurobiological, psychological, and social factors are implicated in the etiology of BPD. With emerging evidence on BPD development in adolescence, the review focused on recent literature to understand the role of psychosocial risk factors. The effects of adverse familial environment, physical, emotional, verbal, and sexual abuse, intergenerational transmission of psychopathological traits, maternal neglect and rejection, low socioeconomic status, bullying victimization, and dating violence were reviewed to understand their role in the development of BPD. BPD is a highly complex, serious, and enduring mental illness that has now been widely accepted to have symptoms that onset in early adolescence and could be diagnosed as early as age 12. BPD symptoms are stable, phenomenologically distinct from externalizing and internalizing disorders, and often present with co-occurring disorders, which during assessment could not explain impairments associated with BPD. New measures like the Difficulties in Emotion Regulation Scale (DERS), detailed developmental histories, understanding of psychosocial risks, shared decision-making, and psychoeducation could assist in early diagnosis and improvement of long-term outcomes. The implementation of evidence-based treatments is a challenge given higher costs and access to services; therefore, modifications in the treatment based on the core principles of these strategies should be considered. It is imperative to screen for psychosocial factors early in higher-risk groups. The assessment of familial factors, parental histories of psychopathologies, and histories of childhood abuse is important in context with impairing symptoms of clinical presentation and dimensional aspects of self-functioning. The role of family therapies, parental psychoeducation, and the integration of trauma-informed care approaches are important for clinical outcomes. Also, coordinated efforts with multiple stakeholders like school awareness programs, anti-bullying policies, legislation, and enforcement of existing laws might be instrumental in addressing issues related to victimization by peers.

Translational Genomic Research: The Association between Genetic Profiles and Cognitive Functioning or Cardiac Function Among Breast Cancer Survivors Completing Chemotherapy

Introduction: Emerging evidence suggests that Chemotherapy (CT) treated breast cancer survivors (BCS) who have "risk variants" in genes may be more susceptible to cognitive impairment (CI) and/or poor cardiac phenotypes. The objective of this preliminary study was to examine whether there is a relationship between genetic variants and objective/subjective cognitive or cardiac phenotypes. Methods and Analysis: BCS were recruited from Moffitt Cancer Center, Morsani College of Medicine, AdventHealth Tampa and Sarasota Memorial Hospital. Genomic DNA were collected at baseline for genotyping analysis. A total of 16 single nucleotide polymorphisms (SNPs) from 14 genes involved in cognitive or cardiac function were evaluated. Three genetic models (additive, dominant, and recessive) were used to test correlation coefficients between genetic variants and objective/subjective measures of cognitive functioning and cardiac outcomes (heart rate, diastolic blood pressure, systolic blood pressure, respiration rate, and oxygen saturation). Results: BCS (207 participants) with a mean age of 56 enrolled in this study. The majority were non-Hispanic white (73.7%), married (63.1%), and received both CT and radiation treatment (77.3%). Three SNPs in genes related to cognitive functioning (rs429358 in APOE, rs1800497 in ANKK1, rs10119 in TOMM40) emerged with the most consistent significant relationship with cognitive outcomes. Among five candidate SNPs related to cardiac functioning, rs8055236 in CDH13 and rs1801133 in MTHER emerged with potential significant relationships with cardiac phenotype. Conclusions: These preliminary results provide initial targets to further examine whether BCS with specific genetic profiles may preferentially benefit from interventions designed to improve cognitive and cardiac functioning following CT.

Translational genomic research: the role of genetic polymorphisms in MBSR program among breast cancer survivors (MBSR[BC])

Genetic variations of breast cancer survivors (BCS) may contribute to level of residual symptoms, such as depression, stress, fatigue, and cognitive impairment. The objective of this study was to investigate whether particular single-nucleotide polymorphisms (SNPs) moderated symptom improvement resulting from the Mindfulness-Based Stress Reduction for Breast Cancer (MBSR[BC]) program. An overarching goal of personalized medicine is to identify individuals as risk for disease and tailor interventions based on genetic profiles of patients with diseases including cancer. BCS were recruited from Moffitt Cancer Center and University of South Florida's Breast Health Program and were randomized to either the 6-week MBSR(BC) program (n = 92) or Usual Care (n = 93). Measures of symptoms, demographic, and clinical history data were attained at baseline, 6 weeks, and 12 weeks. A total of 10 SNPs from eight genes known to be related to these symptoms were studied using genomic DNA extracted from blood. Our results were examined for effect sizes, consistency, and statistical significance (p < .05). Three SNPs (rs4680 in COMT, rs6314 in HTR2A, and rs429358 in APOE) emerged as having the strongest (though relatively weak) and most consistent effects in moderating the impact of the MBSR program on symptom outcomes. Although effects were generally weak, with only one effect withstanding multiple comparisons correction for statistical significance, this translational behavioral research may help start the identification of genetic profiles that moderate the impact of MBSR(BC). The ultimate goal of this study is the development of personalized treatment programs tailored to the genetic profile of each patient.

Association of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A With Clinical Features of Youth-Onset Schizophrenia

We investigated the associations of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A with youth-onset schizophrenia in the Russian population in a case-control study, and the role of the genotype in the severity of clinical features. The association between rs7322347 and schizophrenia (p = 0.0001) is described for the first time. Furthermore, we found a link with rs6280 and rs4680 in females (p = 0.001 and p = 0.02 respectively) and with rs7322347 in males (p = 0.002). Clinical symptoms were assessed on three scales: the Clinician-Rated Dimensions of Psychosis Symptom Severity scale, Positive and Negative Syndrome Scale, and Frontal Assessment Battery. Gender differences in clinical features are of particular interest. In our study we found gender differences in the severity of clinical features-higher scores for delusions (Positive and Negative Syndrome Scale and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) in males and higher scores for depression, delusions, somatic concern, motor retardation, poor attention were found in females.

Practitioner Review: Borderline personality disorder in adolescence--recent conceptualization, intervention, and implications for clinical practice

BACKGROUND

The past decade has seen an unprecedented increase in research activity on personality disorders (PDs) in adolescents. The increase in research activity, in addition to major nosological systems legitimizing the diagnosis of borderline personality disorder (BPD) in adolescents, highlights the need to communicate new research on adolescent personality problems to practitioners.

SCOPE

In this review, we provide up-to-date information on the phenomenology, prevalence, associated clinical problems, etiology, and intervention for BPD in adolescents. Our aim was to provide a clinically useful practitioner review and to dispel long-held myths about the validity, diagnostic utility, and treatability of PDs in adolescents.

FINDINGS AND CONCLUSION

Alongside providing up-to-date information on the phenomenology, prevalence, and etiology, we also report on associated clinical problems and interventions for adolescent BPD. It is only through early active assessment and identification of youngsters with these problems that a lifetime of personal suffering and health system burden can be reduced or altogether avoided. A variety of evidence-based approaches are now available to treat BPD and related clinical problems in young people. Future research should focus on establishing optimal precision in the diagnostic processes in different treatment settings.

Moderating Effects of Genetic Polymorphisms on Improvements in Cognitive Impairment in Breast Cancer Survivors Participating in a 6-Week Mindfulness-Based Stress Reduction Program

Breast cancer (BC) survivors often report cognitive impairment, which may be influenced by single-nucleotide polymorphisms (SNPs). The purpose of this study was to test whether particular SNPs were associated with changes in cognitive function in BC survivors and whether these polymorphisms moderated cognitive improvement resulting from the Mindfulness-Based Stress Reduction for Breast Cancer (MBSR[BC]) program. BC survivors recruited from Moffitt Cancer Center and the University of South Florida's Breast Health Program, who had completed adjuvant radiation and/or chemotherapy treatment, were randomized to either the 6-week MBSR(BC) program (n = 37) or usual care (UC; n = 35) group. Measures of cognitive function and demographic and clinical history data were attained at baseline and at 6 and 12 weeks. A total of 10 SNPs from eight genes known to be related to cognitive function were analyzed using blood samples. Results showed that SNPs in four genes (ankyrin repeat and kinase domain containing 1 [ANKK1], apolipoprotein E [APOE], methylenetetrahydrofolate reductase [MTHFR], and solute carrier family 6 member 4 [SLC6A4]) were associated with cognitive impairment. Further, rs1800497 in ANKK1 was significantly associated with improvements in cognitive impairment in response to MBSR(BC). These results may help to identify individuals who would be better served by MBSR(BC) or other interventions.

Recent advances in the developmental aspects of borderline personality disorder

The aim of the current paper was to review the most recent advances in the developmental aspects of borderline personality disorder (BPD) over the last 3 years to highlight the most significant trends in the field. In so doing, we identify and discuss two exciting new trends: (a) an emphasis on the biological basis of adolescent BPD and (b) empirical evidence in support of long-held theories of the development of BPD. Together, these trends suggest that for the first time, empirical findings are beginning to emerge in support of complex and reciprocal biology × environment interactions over time in the development of BPD. We discuss the emerging literature and highlight the translational impact of this work for the assessment and intervention of adolescent BPD.

Polymorphism in the serotonin receptor 2a (HTR2A) gene as possible predisposal factor for aggressive traits

Aggressive manifestations and their consequences are a major issue of mankind, highlighting the need for understanding the contributory factors. Still, aggression-related genetic analyses have so far mainly been conducted on small population subsets such as individuals suffering from a certain psychiatric disorder or a narrow-range age cohort, but no data on the general population is yet available. In the present study, our aim was to identify polymorphisms in genes affecting neurobiological processes that might explain some of the inter-individual variation between aggression levels in the non-clinical Caucasian adult population. 55 single nucleotide polymorphisms (SNP) were simultaneously determined in 887 subjects who also filled out the self-report Buss-Perry Aggression Questionnaire (BPAQ). Single marker association analyses between genotypes and aggression scores indicated a significant role of rs7322347 located in the HTR2A gene encoding serotonin receptor 2a following Bonferroni correction for multiple testing (p = 0.0007) both for males and females. Taking the four BPAQ subscales individually, scores for Hostility, Anger and Physical Aggression showed significant association with rs7322347 T allele in themselves, while no association was found with Verbal Aggression. Of the subscales, relationship with rs7322347 was strongest in the case of Hostility, where statistical significance virtually equaled that observed with the whole BPAQ. In conclusion, this is the first study to our knowledge analyzing SNPs in a wide variety of genes in terms of aggression in a large sample-size non-clinical adult population, also describing a novel candidate polymorphism as predisposal to aggressive traits.

Variations in 5-HT2A Influence Spatial Cognitive Abilities and Working Memory

Background:

5-hydroxytryptamine receptor 2A (5-HT2A) participates in diverse psychiatric disorders by regulating the activity of serotonin. Some previous studies have also suggested that the receptor is involved in cognitive abilities of disease groups. We hypothesize that some functional genetic variants in 5-HT2A have certain specific influences on cognitive abilities in a normal population.

Method:

To confirm this hypothesis, two polymorphisms (rs6313 and rs4941573) in 5-HT2A were selected, and a population-based study was performed in a young healthy Chinese Han cohort.

Results:

The results indicated that the rs6313 and rs4941573 were associated with touching blocks and mental rotation-3D error ratio in males, and the rs4941573 was associated with visuo-spatial working memory in the whole cohort.

Conclusion:

All the findings suggest that 5-HT2A participates in human spatial cognitive abilities and spatial working memory.

If It Looks Like a Duck and Quacks Like a Duck: Evaluating the Validity of Borderline Personality Disorder in Adolescents

Background:

The validity of borderline personality disorder (BPD) has been a topic of much controversy in psychiatry. Over the last two decades, a wealth of empirical work has challenged long-held concerns regarding the validity of adolescent BPD. However, this research has been conducted within a traditional approach to psychiatric nosology.

Objective:

In this article, we aim to evaluate the validity of adolescent BPD as guided by both the Robins and Guze criteria for the validity of psychiatric constructs and the new National Institute of Mental Health Research Domain Criteria (NIMH RDoC).

Method:

We used the five principles of the Robins and Guze approach to evaluate selected research from our own and other groups regarding the validity of adolescent BPD. These principles include clinical description studies, laboratory studies, studies that delimitate the disorder from other related syndromes, follow-up studies, and family studies.

Results:

Within the Robins and Guze criteria framework, evidence to date supports the validity of adolescent BPD to some extent. However, limitations of the research about the construct validity of adolescent BPD have also been identified, most notably regarding the delimitation of adolescent BPD from other disorders as well as a lack of longitudinal and family studies.

Conclusions:

Given these limitations and the limitations of the Robins and Guze approach to psychiatric nosology, we recommend exploring the potential of the National Institute of Mental Health Research Domain Criteria as a complement to previous work.

Genetic variations in the serotoninergic system and environmental factors contribute to aggressive behavior in Chinese adolescents

Aggressive behavior is a major public health problem worldwide and has been associated with many gene variants, especially those related to the serotonin (5-hydroxytryptamine, 5-HT) system, and environmental factors. However, the overall contribution of serotonin-related genes to aggressive behavior is not well understood. With a sample of 478 healthy Chinese volunteers, this study investigated the relation between aggressive behavior and genetic variations of the serotoninergic system (as characterized by 129 representative polymorphisms) interacting with environmental factors (parental warmth and acceptance; stressful life events). We adopted a system-level approach to identify SNPs and environmental factors associated with aggressive behavior, and estimated their overall contribution to aggressive behavior using multiple regression, which was then verified by permutation analysis. We identified 12 SNPs that made statistically significant contributions to aggressive behavior. Next, main effects, interactions among these SNPs, and interactions between these SNPs and environmental factors were assessed using multiple regression. The final model accounted for approximately 19% of the variance for aggressive behavior. Permutation analysis confirmed that the probability of obtaining these findings by chance was low (p=0.045, permuted for 1000 times). These results showed that genetic variations in the serotoninergic system, combined with environmental risk factors, made a moderate contribution to individual differences in aggressive behavior among a healthy population sample.

Association between genetic polymorphisms in the serotonergic system and comorbid personality disorders among patients with first-episode depression

Studies on the association between genetic polymorphisms and personality disorders have provided inconsistent results. Using the "enriched sample method," the authors of the present study aimed to assess the association between polymorphisms in the serotonergic transmitter system and comorbid personality disorders in patients recently diagnosed with first-episode depression. A total of 290 participants were systematically recruited via the Danish Psychiatric Central Research Register. Diagnoses of personality disorders were assessed by a SCID-II interview, and polymorphisms in the genes encoding the serotonin transporter, serotonin receptors 1A, 2A, 2C, and tryptophan hydroxylase 1 were genotyped. The authors found a significant effect of the length polymorphism in the serotonin transporter gene (5-HTTLPR) on cluster B personality disorder (mainly borderline disorder), but no influence on cluster C personality disorder, and no associations between other polymorphisms and personality disorders. The study adds evidence to the effect of the serotonin transporter gene specifically on cluster B personality disorders.

Genetics of borderline personality disorder: systematic review and proposal of an integrative model

Borderline personality disorder (BPD) is one of the most common mental disorders and is characterized by a pervasive pattern of emotional lability, impulsivity, interpersonal difficulties, identity disturbances, and disturbed cognition. Here, we performed a systematic review of the literature concerning the genetics of BPD, including familial and twin studies, association studies, and gene-environment interaction studies. Moreover, meta-analyses were performed when at least two case-control studies testing the same polymorphism were available. For each gene variant, a pooled odds ratio (OR) was calculated using fixed or random effects models. Familial and twin studies largely support the potential role of a genetic vulnerability at the root of BPD, with an estimated heritability of approximately 40%. Moreover, there is evidence for both gene-environment interactions and correlations. However, association studies for BPD are sparse, making it difficult to draw clear conclusions. According to our meta-analysis, no significant associations were found for the serotonin transporter gene, the tryptophan hydroxylase 1 gene, or the serotonin 1B receptor gene. We hypothesize that such a discrepancy (negative association studies but high heritability of the disorder) could be understandable through a paradigm shift, in which "plasticity" genes (rather than "vulnerability" genes) would be involved. Such a framework postulates a balance between positive and negative events, which interact with plasticity genes in the genesis of BPD.

The presence of both serotonin 1A receptor (HTR1A) and dopamine transporter (DAT1) gene variants increase the risk of borderline personality disorder

Dysfunction in the dopaminergic and serotonergic neurotransmitter systems has been demonstrated to be important in the etiology of borderline personality disorder (BPD). We investigated the relationship of two BPD risk factors, the HTR1A promoter polymorphism -1019C > G (rs6295) and the dopamine transporter (DAT1) repeat allele, with BPD in a major depressive disorder cohort of 367 patients. Out-patients with major depressive disorder were recruited for two treatment trials and assessed for personality disorders, including BPD. DNA samples were collected and the rs6295 polymorphism was detected with a TaqMan(®) assay. The DAT1 repeat allele was genotyped using a modified PCR method. The impact of polymorphisms on BPD was statistically analyzed using uncontrolled logistic and multiple logistic regression models. BPD patients had higher frequencies of the DAT1 9,9 (OR = 2.67) and 9,10 (OR = 3.67) genotypes and also those homozygous HTR1A G allele (OR = 2.03). No significant interactions between HTR1A and DAT1 genotypes, were observed; however, an increased risk of BPD was observed for those patients who were either 9,10; G,G (OR = 6.64) and 9,9; C,G (OR = 5.42). Furthermore, the odds of BPD in patients exhibiting high-risk variants of these two genes differed from those of patients in low-risk groups by up to a factor of 9. Our study provides evidence implicating the importance of the serotonergic and dopaminergic systems in BPD and that the interaction between genes from different neurotransmitters may play a role in the susceptibility to BPD.

Candidate gene associations with withdrawn behavior

BACKGROUND

Social withdrawal is a core neuropsychiatric phenomenon in developmental psychopathology. Its presence predicts psychopathology across many domains, including depression, psychosis, autism, anxiety, and suicide. Withdrawn behavior is highly heritable, persistent, and characteristically worsens without intervention. To date, few studies have successfully identified genetic associations with withdrawn behavior, despite the abundance of evidence of its heritability. This may be due to reliance of categorical over dimensional measures of the behaviorally inhibited phenotype. The aim of this study is to identify associations between known psychiatric candidate genes and a dimensionally derived measure of withdrawn behavior.

METHODS

Genetic information was collected on 20 single-nucleotide polymorphisms (SNPs) from a custom-designed SNP chip and TAQMAN arrays of 4 variable number of tandem repeat (VNTR) genes for 551 individuals from 187 families. Linear mixed modeling was employed to examine the relationship between genotypes of interest and Child Behavior Checklist (CBCL) Withdrawn Behavior Subscale Score (WBS) while controlling for gender and age through multiple linear regressions.

RESULTS

Withdrawn behavior was highly associated with polymorphism rs6314 of the serotonin receptor 2A (HTR2A) [p = .009, estimate = 0.310 (bootstrap 95% CI 0.155-0.448), bootstrap p = .001] and rs1800544 of the alpha 2-adrenergic (ADRA2A) [p = .001, estimate = -0.310 (bootstrap 95% CI -0.479 to -0.126), bootstrap p = .001] genes after correction for gender and age. The association between withdrawn behavior and ADRA2A was stronger for younger children.

CONCLUSIONS

HTR2A and ADRA2A genes are associated with withdrawn behavior. This reinforces the role of catecholaminergic genes in the heritability of withdrawn behavior.

Genetic modulation of borderline personality disorder: systematic review and meta-analysis

Borderline personality disorder (BPD) is a highly prevalent psychiatric disorder with high morbidity and mortality. Early theories ascribed an environmental etiology of BPD, but growing evidence supports a genetic vulnerability as well. The primary aim of this study was to systematically review genetic association studies focused on BPD. PubMed, ISI Web of Knowledge and PsycINFO databases were searched for studies published until December 2012. Meta-analyses were also performed when three or more studies reported genetic data on the same polymorphism. Data were analyzed with Cochrane Collaboration Review Manager Software (RevMan, version 5.0). Quality and publication bias were assessed. The systematic review of association studies examining genetic polymorphisms and BPD produced conflicting results. Meta-analyses were performed for three serotonergic polymorphisms: two common polymorphisms of the serotonin transporter gene (SLC6A4), the promoter insertion/deletion (5-HTTLPR) and the intron 2 VNTR (STin2 VNTR), and the rs1800532 (A218C) polymorphism of the tryptophan hydroxylase 1 gene (TPH1), all showing no association. No direct role of genetic polymorphisms was found in BPD. However, a few studies only are present in literature to draw definite conclusions. Further studies focusing on gene × gene and gene × environment interactions are needed to more deeply dissect the genetic role in the modulation of BPD.

HTR2A gene polymorphisms and Inward and Outward Personal Meaning Organisations

Nardi B, Piva F, Turchi C, Giulietti M, Castellucci G, Arimatea E, Rocchetti D, Rocchetti G, Principato G, Tagliabracci A, Bellantuono C. HTR2A gene polymorphisms and Inward and Outward Personal Meaning Organisations.

Objective:Caregiver behaviours and emotional expressions may induce development of two basic categories of constructing identity and of regulating cognitive and emotional processes: an Inward or an Outward Personal Meaning Organisation (PMO). Inwards read environmental signals through their internal activations. Their emotions are more distinct, and reciprocity is more based on physical distance (protection, loneliness). Outwards read internal activations through the environment. Their emotions are more blurred, and reciprocity is more based on a semantic sight of relations (approval, rules).

It has recently been shown that PMO development may also have physiological and genetic bases. In a functional magnetic resonance imaging (fMRI) study, Inward and Outward subjects showed different amygdala activation patterns and an association with the SLC6A4 serotonin transporter gene 5-HTTLPR polymorphism.

Methods:In this work, 149 healthy subjects were examined with respect to Inward and Outward PMOs. We explored the association with 10 serotonin receptor 2A (HTR2A) gene single nucleotide polymorphisms (SNPs) selected by bioinformatics methods.

Results:An intronic SNP (rs55948462) was found to be significantly associated with an Inward and an Outward PMOs development. However, after statistical adjustments, these results did not remain significant.

Conclusion:We did not find associations between considered SNPs and Inward/Outward PMOs. However, the role of HTR2A polymorphisms was not considered in this study and that of the other serotonin-related genes should be valued.

Amygdala and hippocampal volume reductions as candidate endophenotypes for borderline personality disorder: a meta-analysis of magnetic resonance imaging studies

Borderline personality disorder (BPD) is a genetically influenced psychiatric illness with disruptions in neural systems supporting cognition and emotion regulation. Volumetric decreases of the hippocampus and amygdala may characterize BPD and serve as putative endophenotypes for the illness. The purpose of the present study was to evaluate whether the magnitude of these volume reductions and their associations with state-of-illness factors and psychiatric disorders which often co-occur with BPD warrant their consideration as potential endophenotypes. Volumetric magnetic resonance imaging results from 11 studies comprising 205 BPD patients and 222 healthy controls were quantitatively synthesized using meta-analytic techniques. Patients showed an average 11% and 13% decrease in the size of the hippocampus and amygdala, respectively. These volumetric differences were not attenuated in patients being treated with psychotropic medications. Comorbid depression, post-traumatic stress disorder, and substance use disorders were unrelated to volumetric decreases in either structure. These findings suggest modest volume reductions of the amygdala and hippocampus bilaterally in BPD which cannot be attributed to illness state or comorbid psychopathology. Decreased volumes of these key limbic structures may hold promise as candidate endophenotypes for BPD.

Developmental pathways to borderline personality disorder

This paper reviews recent studies of biological and environmental risk and protective factors and patterns of continuity leading to borderline personality disorder (BPD). It focuses on prospective studies of children and adolescents and studies of young people with borderline pathology, reporting findings from genetics, neurobiology, experimental psychopathology, environmental risk, and precursor signs and symptoms. Studies of individuals earlier in the course of BPD demonstrate relatively consistent environmental risk factors, but neurobiological and experimental psychopathology findings are still inconsistent. Also, temperamental and mental state abnormalities that resemble aspects of the BPD phenotype emerge in childhood and adolescence and presage the BPD syndrome in adolescence or adulthood. Further work is required to better understand the roles that all these factors play in the developmental pathways to BPD and to increase their specificity for BPD in order to facilitate prevention and early intervention.

The interaction between serotonin receptor 2A and catechol-O-methyltransferase gene polymorphisms is associated with the novelty-seeking subscale impulsiveness

OBJECTIVE

Novelty seeking is a trait that has been consistently associated with problem behaviours. There is evidence for heritability of novelty seeking, but the molecular genetic basis of the trait is still widely unclear.

METHODS

The interaction between polymorphisms of catechol-O-methyltransferase (COMT) and serotonin receptor 2A genes was examined in relation to novelty seeking and its different subscales in healthy Finnish adults. A subsample of 1214 participants derived from a population-based sample was genotyped for the COMT Val158Met (rs4680) and HTR2A T102C (rs6313) genes. Novelty seeking was measured twice, with a 4-year interval, using Cloninger's Temperament and Character Inventory.

RESULTS

The interaction between COMT Val158Met and HTR2A T102C polymorphisms was found to be associated with subscale impulsiveness. T/T carriers of HTR2A T102C polymorphism, that also had Met/Met genotype of COMT Val158Met single nucleotide polymorphism, scored significantly higher on impulsiveness than Val allele carriers (P=0.005).

CONCLUSION

Our results suggest that the interaction between dopaminergic and serotonergic genes might underlie impulsiveness. Together with earlier research our results also stress the importance of considering novelty seeking as a heterogeneous trait with its subscales having different genetic backgrounds.

[Contribution of neurobiology to our knowledge of borderline personality disorder]

Affect dysregulation and impulsivity are the main topics of neurobiological research in borderline personality disorder. Affect dysregulation subsumes enhanced resting arousal, increased emotional responsiveness as well as deficient emotional regulation and is associated with structural and functional abnormalities in a prefrontal-limbic network, above all orbitofrontal hypoactivity and amygdalar as well as insular hyperactivity. Impulsivity describes a lack of future-oriented problem solving style as well as a decreased threshold for motoric responses and is associated with decreased serotonergic activity in the ventral prefrontal cortex. Future research has to clarify how specific the findings of borderline personality disorder are and how far temperament dimensions, such as neuroticism can explain the neurobiological deviations from the norm.

Tryptophan-hydroxylase 2 haplotype association with borderline personality disorder and aggression in a sample of patients with personality disorders and healthy controls

BACKGROUND

There is a decreased serotonergic function in impulsive aggression and borderline personality disorder (BPD), and genetic association studies suggest a role of serotonergic genes in impulsive aggression and BPD. Only one study has analyzed the association between the tryptophan-hydroxylase 2 (TPH2) gene and BPD. A TPH2 "risk" haplotype has been described that is associated with anxiety, depression and suicidal behavior.

METHODS

We assessed the relationship between the previously identified "risk" haplotype at the TPH2 locus and BPD diagnosis, impulsive aggression, affective lability, and suicidal/parasuicidal behaviors, in a well-characterized clinical sample of 103 healthy controls (HCs) and 251 patients with personality disorders (109 with BPD). A logistic regression including measures of depression, affective lability and aggression scores in predicting "risk" haplotype was conducted.

RESULTS

The prevalence of the "risk" haplotype was significantly higher in patients with BPD compared to HCs. Those with the "risk" haplotype have higher aggression and affect lability scores and more suicidal/parasuicidal behaviors than those without it. In the logistic regression model, affect lability was the only significant predictor and it correctly classified 83.1% of the subjects as "risk" or "non-risk" haplotype carriers.

CONCLUSIONS

We found an association between the previously described TPH2 "risk" haplotype and BPD diagnosis, affective lability, suicidal/parasuicidal behavior, and aggression scores.

The genetic epidemiology of personality disorders

Genetic epidemiologic studies indicate that all ten personality disorders (PDs) classified on the DSM-IV axis II are modestly to moderately heritable. Shared environmental and nonadditive genetic factors are of minor or no importance. No sex differences have been identified. Multivariate studies suggest that the extensive comorbidity between the PDs can be explained by three common genetic and environmental risk factors. The genetic factors do not reflect the DSM-IV cluster structure, but rather: i) broad vulnerability to PD pathology or negative emotionality; ii) high impulsivity/low agreeableness; and iii) introversion. Common genetic and environmental liability factors contribute to comorbidity between pairs or clusters of axis I and axis II disorders. Molecular genetic studies of PDs, mostly candidate gene association studies, indicate that genes linked to neurotransmitter pathways, especially in the serotonergic and dopaminergic systems, are involved. Future studies, using newer methods like genome-wide association, might take advantage of the use of endophenotypes.

Dopamine and serotonin systems modify environmental effects on human behavior: a review

The relative influences of genetic and environmental factors in the development of human behavior have been a long-term topic for an intense debate. Recent behavioral genetic studies suggest focusing on the joint effect of genes and environment, and especially on the life-course developmental interplay between nature and nurture. Vulnerability to environmental adversities and sensitivity to its benefits may be conditional on genetic background, and regarding psychological outcomes, these kinds of gene x environment interactions may be of higher importance than direct gene-trait associations. In our recent series of studies, we have shown that different variants of serotonergic and dopaminergic genes may moderate the influence of environmental conditions on a range of psychological outcomes, i.e. temperament, depression, hostility, and educational attainment. These studies suggest that depending on their genotype, people may be differentially sensitive to the environmental conditions they encounter. In the light of these results it seems highly plausible that the effects of genes may become evident only when studied in the context of environmental factors.

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.

Investigation of 17 candidate genes for personality traits confirms effects of the HTR2A gene on novelty seeking

Genes involved in serotonergic and dopaminergic neurotransmission have been hypothesized to affect different aspects of personality, but findings from genetic association studies did not provide conclusive results so far. In previous studies, however, only one or a few polymorphisms within single genes were investigated neglecting the possibility that the genetic associations might be more complex comprising several genes or gene regions. To overcome this limitation, we performed an extended genetic association study analyzing 17 serotonergic (SLC6A4, HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR6, MAOA, TPH1, TPH2) and dopaminergic genes (SLC6A3, DRD2, DRD3, DRD4, COMT, MAOA, TH, DBH), which have been previously reported to be implicated with personality traits. One hundred and ninety-five single nucleotide polymorphisms (SNPs) within these genes were genotyped with the Illumina BeadChip technology (HumanHap300, Human-1) in a sample of 366 mentally healthy Caucasians. Additionally, we tried to replicate our results in an independent sample of further 335 Caucasians. Personality traits in both samples were assessed with the German version of Cloninger's Tridimensional Personality Questionnaire. From 30 SNPs showing associations at a nominal level of significance, two intronic SNPs, rs2770296 and rs927544, both located in the HTR2A gene, withstood correction for multiple testing. These SNPs were associated with the personality trait novelty seeking. The effect of rs927544 could be replicated for the novelty seeking subscale extravagance, and the same SNP was also associated with extravagance in the combined samples. Our results show that HTR2A polymorphisms modulate facets of novelty seeking behaviour in healthy adults suggesting that serotonergic neurotransmission is involved in this phenotype.

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.

Antagonism of serotonergic 5-HT2A/2C receptors: mutual improvement of sleep, cognition and mood?

Serotonin [5-hydroxytryptamine (5-HT)] and 5-HT receptors are involved in sleep and in waking functions such as cognition and mood. Animal and human studies support a particular role for the 5-HT(2A) receptor in sleep, which has led to renewed interest in this receptor subtype as a target for the development of novel pharmacological agents to treat insomnia. Focusing primarily on findings in healthy human volunteers, a review of the available data suggests that antagonistic interaction with 5-HT(2A) receptors (and possibly also 5-HT(2C) receptors) prolongs the duration of slow wave sleep and enhances low-frequency (< 7 Hz) activity in the sleep electroencephalogram (EEG), a widely accepted marker of sleep intensity. Despite certain differences, the changes in sleep and the sleep EEG appear to be remarkably similar to those of physiologically more intense sleep after sleep deprivation. It is currently unclear whether these changes in sleep are associated with improved vigilance, cognition and mood during wakefulness. While drug-induced interaction with sleep must be interpreted cautiously, too few studies are available to provide a clear answer to this question. Moreover, functional relationships between sleep and waking functions may differ between healthy controls and patients with sleep disorders. A multimodal approach investigating subjective and objective aspects of sleep and wakefulness provides a promising research avenue for shedding light on the complex relationships among 5-HT(2A/2C) receptor-mediated effects on sleep, the sleep EEG, cognition and mood in health and various diseases associated with disturbed sleep and waking functions.

A genome-wide scan for Eysenckian personality dimensions in adolescent twin sibships: psychoticism, extraversion, neuroticism, and lie

We report the first genome-wide scan of adolescent personality. We conducted a genome-wide scan to detect linkage for measures of adolescent Psychoticism, Extraversion, Neuroticism, and Lie from the Junior Eysenck Personality Questionnaire. Data are based on 1,280 genotyped Australian adolescent twins and their siblings. The highest linkage peaks were found on chromosomes 16 and 19 for Neuroticism, on chromosomes 1, 7, 10, 13 m, and 18 for Psychoticism, and on chromosomes 2 and 3 for Extraversion.

Serotonin genes and gene-gene interactions in borderline personality disorder in a matched case-control study

Lines of evidence suggest serotonin genes are susceptibility candidates in borderline personality disorder (BPD). However, few molecular genetic studies on BPD have been reported, especially an overall lack of study on epistatic interactions. We genotyped 27 polymorphisms in 7 serotonin genes in 113 Caucasian BPD patients and matched (sex, age and ethnicity) controls. Program UNPHASED was used to perform association analyses for genotypes, alleles and haplotypes with a permutation test of 10,000 simulations. The Multifactor Dimensionality Reduction analysis was used to examine gene-gene interactions in serotonin system, including three other genes (5-HTT, 5-HT2A and MAOA) that we previously reported. Genotype and allele analyses showed that BPD significantly associated with 5-HT2C and TPH2. BPD patients had high frequencies of the 5-HT2C rs6318G allele (p=0.021) and G/G genotype (OR=2.25); and TPH2 rs2171363T allele (p=0.001) and T containing genotypes (OR=3.40). The 5-HT1A, 5-HT1B, 5-HT1D, 5-HT3A and TPH1 showed no significant association with BPD for genotype, allele and haplotype analyses. We also detected significant interactions between 5-HT2C and TPH2 (p=0.001), and among 5-HT2C, 5-HTT, MAOA and TPH2 (p=0.001) in BPD. Patients with 5-HT2C rs6318G/G genotype had a high frequency of TPH2 rs2171363C/T genotype compared with controls. Our study indicates ""that serotonin genes and their interactions may play a role in the susceptibility to borderline personality disorder.

Association analysis of SCN9A gene variants with borderline personality disorder

Borderline personality disorder (BPD) is a serious psychiatric disorder affecting about 1-2% of the general population. Key features of BPD are emotional instability, strong impulsivity, repeated self-injurious behavior (SIB) and dissociation. In the etiology of BPD and its predominant symptoms, genetic factors have been suggested. The voltage-gated sodium channel Nav1.7 is expressed in sensory neurons and in the hippocampus, a key region of the limbic system probably dysfunctional in BPD and dissociative disorders. The alpha-subunit of Nav1.7 is encoded by the SCN9A gene on chromosome 2 and variations of SCN9A can lead to complete inability to sense pain. The aim of the present study was to test for associations between SCN9A gene variants and BPD as well as BPD-related phenotypes. We genotyped ten tagging single nucleotide polymorphisms (SNPs) within the SCN9A gene in 161 well-defined Caucasian BPD patients and 156 healthy controls. We found no globally significant association of SCN9A markers with BPD at level 5%. However, in the female and in the male subsample, different SCN9A markers and individual haplotypes showed uncorrected p-values<0.05. In addition, p-values<0.05 were observed in the analysis of associations between SCN9A markers and dissociative symptoms. Although our results were largely negative, replication studies in an independent sample are warranted to follow up on the potential role of SCN9A gene variants in BPD and dissociative symptoms, paying special attention to a possible gender different etiology.

Genetics of personality disorders

This review of the literature on genetic contributions to the etiology of personality disorders broadly follows the DSM classification, and begins by evaluating the current evidence for genetic influences on the DSM axis II disorders. One of the most exciting directions in psychiatric genetics is the rapidly developing field of molecular genetic studies aiming to identify specific genes correlated with psychiatric phenotypes. Personality disorders, like most other psychiatric diagnostic categories, are etiologically complex, which implies that they are influenced by several genes and several environmental factors. The interplay between genes and the environment is a field that is receiving increasing attention and is addressed both in relation to quantitative and molecular methods.

Recent advances in the biological study of personality disorders

While it is premature to provide a simple model for the vulnerability to the development of either borderline (BPD) or schizotypal (SPD) personality disorder, it is clear that these heritable disorders lend themselves to fruitful neurobiological exploration. The most promising findings in BPD suggest that a diminished top-down control of affective responses, which is likely to relate to deceased responsiveness of specific midline regions of prefrontal cortex, may underlie the affective hyperresponsiveness in this disorder. In addition, genetic and neuroendocrine and molecular neuroimaging findings point to a role for serotonin in this affective disinhibition. Clearly SPD falls within the schizophrenia spectrum, but precisely the nature of what predicts full-blown schizophrenia as opposed to the milder symptoms of SPD is not yet clear.

Genetic correlates of adult attachment style

Attachment theory attempts to explain effects of social experiences, not genes, on personality development. Most studies of the development of attachment insecurities support this emphasis on social experiences rather than genes, although there are exceptions. In the present study, the authors examine associations between attachment insecurities and particular genetic polymorphisms related to emotions and social behavior. They find that (a) anxious attachment is associated with a polymorphism of the DRD2 dopamine receptor gene, (b) avoidant attachment is associated with a polymorphism of the 5HT2A serotonin receptor gene, and (c) the rs53576 A polymorphism of the OXTR oxytocin receptor gene is not associated with attachment insecurities. These findings suggest that attachment insecurities are partially explained by particular genes, although there is still a great deal of individual difference variance that remains to be explained by other genes or social experiences.

5-HT2A SNPs and the Temperament and Character Inventory

Temperamental traits, the most basic part of personality, have been largely correlated with neurotransmitter systems and are under genetic control. Among serotonin candidates, the 2A receptor (5-HT(2A)) received considerable attention. We analyzed four SNPs (rs643627, rs594242, rs6311 and rs6313) in the 5-HT(2A) gene and their association with personality traits, as measured with the Temperament and Character Inventory (TCI). The sample was composed of three sub-groups: two German sub-samples, consisting of a healthy group of 289 subjects (42.6% males, mean age: 45.2+/-14.9) and a psychiatric patient group of 111 suicide attempters (38.7% males, mean age: 39.2+/-13.6), and an Italian sub-sample, composed of 60 mood disorder patients (35.0% males, mean age: 44.0+/-14.8). Controlling for sex, age and educational level, the SNPs were not strongly associated with personality dimensions. Only the rs594242 showed an association with Self-Directedness (p=0.003) in the German sample, while rs6313 was marginally associated with Novelty Seeking (p=0.01) in the Italian sample. We conclude that 5-HT(2A) SNPs may marginally modulate personality traits but further studies are required.