Sex-stratified gene-by-environment genome-wide interaction study of trauma, posttraumatic-stress, and suicidality

Using the Strategy of Genome-Wide Association Studies to Identify Genetic Markers of Suicidal Behavior: A Narrative Review

BACKGROUND

Several studies involving various suicidal phenotypes based on the strategy of the search of genome-wide associations with single nucleotide polymorphisms have been performed recently. These studies need to be generalized.

AIM

To systematize the findings of a number of genome-wide association studies (GWAS) for suicidal phenotypes, annotate the identified markers, analyze their functionality, and possibly substantiate the hypothesis holding that these phenotypes reflect a nonspecific set of gene variants that are relevant as relates to stress-vulnerability as a key endophenotype of suicidal behavior (SB).

METHODS

A search on the PubMed and related resources using the combinations "suicide AND GWAS" and "suicidal behavior AND GWAS" was performed. It yielded a total of 34 independent studies and meta-analyses.

RESULTS

For the 10 years since such studies emerged, they have undergone significant progress. Estimates of the SNP heritability of SB in some cases are comparable with estimates of heritability based on the twin method. Many studies show a high genetic correlation with the genomic markers of the most common mental disorders (depression, bipolar disorder, schizophrenia, post-traumatic stress disorder). At the same time, a genomic architecture specific to SB is also encountered. Studies utilizing the GWAS strategy have not revealed any associations of SB with candidate genes that had been previously studied in detail (different neurotransmitters, stress response system, polyamines, etc.). Frequently reported findings from various studies belong in three main groups: 1) genes involved in cell interactions, neurogenesis, the development of brain structures, inflammation, and the immune responses; 2) genes encoding receptors for neurotrophins and various components of the intracellular signaling systems involved in synaptic plasticity, embryonic development, and carcinogenesis; and 3) genes encoding various neuro-specific proteins and regulators.

CONCLUSION

In general, GWAS in the field of suicidology mainly serve the purpose of a deeper understanding of the pathophysiology of suicidal behavior. However, they also demonstrate growing capability in terms of predicting and preventing suicide, especially when calculating the polygenic risk score among certain populations (psychiatric patients) and in combination with tests of different modalities. From our point of view, there exists a set of markers revealed by the GWAS strategy that seems to point to a leading role played by stress vulnerability, an endophenotype that is formed during early development and which subsequently comes to play the role of key pathogenetic mechanism in SB.

Divorce, genetic risk, and suicidal thoughts and behaviors in a sample with recurrent major depressive disorder

BACKGROUND

Theories of risk for suicidal thoughts and behaviors (STB) implicate both interpersonal and biological factors. Divorce/separation and aggregate genetic liability are robustly associated with STB, but have seldom been evaluated in conjunction with one another. Furthermore, whether these factors are effective predictors in high-risk populations is not clear.

METHODS

Analyses were conducted in a sample of Han Chinese women with severe recurrent major depressive disorder (maximum N = 4380). Logistic regressions were used to evaluate the associations between divorce/separation and polygenic scores (PGS) for suicidal ideation or behavior with STB. Where appropriate, additive interactions between divorce and PGS were tested.

RESULTS

Divorce/separation was significantly associated with increased risk of suicidal ideation, plans, and attempts (odds ratios = 1.28-1.61). PGS for suicidal ideation were not associated with STB, while PGS for suicidal behavior were associated with ideation and plans (odds ratios = 1.08-1.09). There were no significant interactions between divorce/separation and PGS.

CONCLUSIONS

Consistent with theories of suicidality, the disruption or end of an important interpersonal relationship is an indicator of risk for STB. Aggregate genetic liability for suicidal behavior more modestly contributes to risk, but does not exacerbate the negative impact of divorce. Thus, even within a high-risk sample, interpersonal and biological exposures distinguish between those who do and do not experience STB, and could motivate targeted screening. Further research is necessary to evaluate whether and how the context of divorce contributes to variation in its effect on STB risk.

The race-based stress reduction intervention (RiSE) study on African American women in NYC and Chicago: Design and methods for complex genomic analysis

RiSE study aims to evaluate a race-based stress-reduction intervention as an effective strategy to improve coping and decrease stress-related symptoms, inflammatory burden, and modify DNA methylation of stress response-related genes in older AA women. This article will describe genomic analytic methods to be utilized in this longitudinal, randomized clinical trial of older adult AA women in Chicago and NYC that examines the effect of the RiSE intervention on DNAm pre- and post-intervention, and its overall influence on inflammatory burden. Salivary DNAm will be measured at baseline and 6 months following the intervention, using the Oragene-DNA kit. Measures of perceived stress, depressive symptoms, fatigue, sleep, inflammatory burden, and coping strategies will be assessed at 4 time points including at baseline, 4 weeks, 8 weeks, and 6 months. Genomic data analysis will include the use of pre-processed and quality-controlled methylation data expressed as beta (β) values. Association analyses will be performed to detect differentially methylated sites on the targeted candidate genes between the intervention and non-intervention groups using the Δβ (changes in methylation) with adjustment for age, health behaviors, early life adversity, hybridization batch, and top principal components of the probes as covariates. To account for multiple testing, we will use FDR adjustment with a corrected p-value of <0.05 regarded as statistically significant. To assess the relationship between inflammatory burden and Δβ among the study samples, we will repeat association analyses with the inclusion of individual inflammation protein measures. ANCOVA will be used because it is more statistically powerful to detect differences.

Gene Discovery and Biological Insights into Anxiety Disorders from a Multi-Ancestry Genome-wide Association Study of >1.2 Million Participants

We leveraged information from more than 1.2 million participants to investigate the genetics of anxiety disorders across five continental ancestral groups. Ancestry-specific and cross-ancestry genome-wide association studies identified 51 anxiety-associated loci, 39 of which are novel. Additionally, polygenic risk scores derived from individuals of European descent were associated with anxiety in African, Admixed-American, and East Asian groups. The heritability of anxiety was enriched for genes expressed in the limbic system, the cerebral cortex, the cerebellum, the metencephalon, the entorhinal cortex, and the brain stem. Transcriptome- and proteome-wide analyses highlighted 115 genes associated with anxiety through brain-specific and cross-tissue regulation. We also observed global and local genetic correlations with depression, schizophrenia, and bipolar disorder and putative causal relationships with several physical health conditions. Overall, this study expands the knowledge regarding the genetic risk and pathogenesis of anxiety disorders, highlighting the importance of investigating diverse populations and integrating multi-omics information.

Inhibition of miR-143-3p Restores Blood-Testis Barrier Function and Ameliorates Sertoli Cell Senescence

Due to the increasing trend of delayed childbirth, the age-related decline in male reproductive function has become a widely recognized issue. Sertoli cells (SCs) play a vital role in creating the necessary microenvironment for spermatogenesis in the testis. However, the mechanism underlying Sertoli cell aging is still unclear. In this study, senescent Sertoli cells showed a substantial upregulation of miR-143-3p expression. miR-143-3p was found to limit Sertoli cell proliferation, promote cellular senescence, and cause blood-testis barrier (BTB) dysfunction by targeting ubiquitin-conjugating enzyme E2 E3 (UBE2E3). Additionally, the TGF-β receptor inhibitor SB431542 showed potential in alleviating age-related BTB dysfunction, rescuing testicular atrophy, and reversing the reduction in germ cell numbers by negatively regulating miR-143-3p. These findings clarified the regulatory pathways underlying Sertoli cell senescence and suggested a promising therapeutic approach to restore BTB function, alleviate Sertoli cell senescence, and improve reproductive outcomes for individuals facing fertility challenges.

Effects of sex and gender on the etiologies and presentation of select internalizing psychopathologies

The internalizing spectrum encompasses a subset of psychopathologies characterized by emotional liability, anhedonia, anxiousness, distress, and fear, and includes, among others, diagnoses of major depressive disorder (MDD), generalized anxiety disorder (GAD), and posttraumatic stress disorder (PTSD). In this review, we describe the vast body of work highlighting a role for sex and gender in the environment, symptom onset, genetic liability, and disorder progression and comorbidities of MDD, GAD, and PTSD. We also point the reader to different language used in diverse fields to describe sexual and gender minorities that may complicate the interpretation of emerging literature from the social sciences, psychiatric and psychological sciences, and genetics. Finally, we identify several gaps in knowledge that we hope serve as launch-points for expanding the scope of psychiatric studies beyond binarized sex-stratification. Despite being under-represented in genomics studies, placing emphasis on inclusion of sexual and gender diverse participants in these works will hopefully improve our understanding of disorder etiology using genetics as one tool to inform how biology (e.g., hormone concentration) and environmental variables (e.g., exposure to traumatic events) contribute to differences in symptom onset, pattern, and long-term trajectory.

Association between suicidal ideation and tandem repeats in contactins

Background

Death by suicide is one of the leading causes of death among adolescents. Genome-wide association studies (GWAS) have identified loci that associate with suicidal ideation and related behaviours. One such group of loci are the six contactin genes (CNTN1-6) that are critical to neurodevelopment through regulating neurite structure. Because single nucleotide polymorphisms (SNPs) detected by GWAS often map to non-coding intergenic regions, we investigated whether repetitive variants in CNTNs associated with suicidality in a young cohort aged 8 to 21. Understanding the genetic liability of suicidal thought and behavior in this age group will promote early intervention and treatment.

Methods

Genotypic and phenotypic data were obtained from the Philadelphia Neurodevelopment Cohort (PNC). Across six CNTNs, 232 short tandem repeats (STRs) were analyzed in up to 4,595 individuals of European ancestry who expressed current, previous, or no suicidal ideation. STRs were imputed into SNP arrays using a phased SNP-STR haplotype reference panel from the 1000 Genomes Project. We tested several additive and interactive models of locus-level burden (i.e., sum of STR alleles) with respect to suicidal ideation. Additive models included sex, birth year, developmental stage ("DevStage"), and the first 10 principal components of ancestry as covariates; interactive models assessed the effect of STR-by-DevStage considering all other covariates.

Results

CNTN1-[T]N interacted with DevStage to increase risk for current suicidal ideation (CNTN1-[T]N-by-DevStage; p = 0.00035). Compared to the youngest age group, the middle (OR = 1.80, p = 0.0514) and oldest (OR = 3.82, p = 0.0002) participant groups had significantly higher odds of suicidal ideation as their STR length expanded; this result was independent of polygenic scores for suicidal ideation.

Discussion

These findings highlight diversity in the genetic effects (i.e., SNP and STR) acting on suicidal thoughts and behavior and advance our understanding of suicidal ideation across childhood and adolescence.

The role of substance use disorders in the transition from suicide attempt to suicide death: a record linkage study of a Swedish cohort

BACKGROUND

Suicidal behavior and substance use disorders (SUDs) are important public health concerns. Prior suicide attempts and SUDs are two of the most consistent predictors of suicide death, and clarifying the role of SUDs in the transition from suicide attempt to suicide death could inform prevention efforts.

METHODS

We used national Swedish registry data to identify individuals born 1960-1985, with an index suicide attempt in 1997-2017 (N = 74 873; 46.7% female). We assessed risk of suicide death as a function of registration for a range of individual SUDs. We further examined whether the impact of SUDs varied as a function of (i) aggregate genetic liability to suicidal behavior, or (ii) age at index suicide attempt.

RESULTS

In univariate models, risk of suicide death was higher among individuals with any SUD registration [hazard ratios (HRs) = 2.68-3.86]. In multivariate models, effects of specific SUDs were attenuated, but remained elevated for AUD (HR = 1.86 95% confidence intervals 1.68-2.05), opiates [HR = 1.58 (1.37-1.82)], sedatives [HR = 1.93 (1.70-2.18)], and multiple substances [HR = 2.09 (1.86-2.35)]. In secondary analyses, the effects of most, but not all, SUD were exacerbated by higher levels of genetic liability to suicide death, and among individuals who were younger at their index suicide attempt.

CONCLUSIONS

In the presence of a strong predictor of suicide death - a prior attempt - substantial predictive power is still attributable to SUDs. Individuals with SUDs may warrant additional suicide screening and prevention efforts, particularly in the context of a family history of suicidal behavior or early onset of suicide attempt.

Genetic liability to suicidal thoughts and behaviors and risk of suicide attempt in US military veterans: moderating effects of cumulative trauma burden

BACKGROUND

Little is known about environmental factors that may influence associations between genetic liability to suicidality and suicidal behavior.

METHODS

This study examined whether a suicidality polygenic risk score (PRS) derived from a large genome-wide association study (N = 122,935) was associated with suicide attempts in a population-based sample of European-American US military veterans (N = 1664; 92.5% male), and whether cumulative lifetime trauma exposure moderated this association.

RESULTS

Eighty-five veterans (weighted 6.3%) reported a history of suicide attempt. After adjusting for sociodemographic and psychiatric characteristics, suicidality PRS was associated with lifetime suicide attempt (odds ratio 2.65; 95% CI 1.37-5.11). A significant suicidality PRS-by-trauma exposure interaction emerged, such that veterans with higher levels of suicidality PRS and greater trauma burden had the highest probability of lifetime suicide attempt (16.6%), whereas the probability of attempts was substantially lower among those with high suicidality PRS and low trauma exposure (1.4%). The PRS-by-trauma interaction effect was enriched for genes implicated in cellular and developmental processes, and nervous system development, with variants annotated to the DAB2 and SPNS2 genes, which are implicated in inflammatory processes. Drug repurposing analyses revealed upregulation of suicide gene-sets in the context of medrysone, a drug targeting chronic inflammation, and clofibrate, a triacylglyceride level lowering agent.

CONCLUSION

Results suggest that genetic liability to suicidality is associated with increased risk of suicide attempt among veterans, particularly in the presence of high levels of cumulative trauma exposure. Additional research is warranted to investigate whether incorporation of genomic information may improve suicide prediction models.

Trauma Matters: Integrating Genetic and Environmental Components of PTSD

Trauma is ubiquitous, but only a subset of those who experience trauma will develop posttraumatic stress disorder (PTSD). In this review, it is argued that to determine who is at risk of developing PTSD, it is critical to examine the genetic etiology of the disorder and individual trauma profiles of those who are susceptible. First, the state of current PTSD genetic research is described, with a particular focus on studies that present evidence for trauma type specificity, or for differential genetic etiology according to gender or race. Next, approaches that leverage non-traditional phenotyping approaches are reviewed to identify PTSD-associated variants and biology, and the relative advantages and limitations inherent in these studies are reflected on. Finally, it is discussed how trauma might influence the heritability of PTSD, through type, risk factors, genetics, and associations with PTSD symptomology.

The Future of Social Determinants of Health: Looking Upstream to Structural Drivers

Policy Points Policies that redress oppressive social, economic, and political conditions are essential for improving population health and achieving health equity. Efforts to remedy structural oppression and its deleterious effects should account for its multilevel, multifaceted, interconnected, systemic, and intersectional nature. The U.S. Department of Health and Human Services should facilitate the creation and maintenance of a national publicly available, user-friendly data infrastructure on contextual measures of structural oppression. Publicly funded research on social determinants of health should be mandated to (a) analyze health inequities in relation to relevant data on structural conditions and (b) deposit the data in the publicly available data repository.

How to save a life: From neurobiological underpinnings to psychopharmacotherapies in the prevention of suicide

The impact of suicide on our societies, mental healthcare, and public health is beyond questionable. Every year approximately 700 000 lives are lost due to suicide around the world (WHO, 2021); more people die by suicide than by homicide and war. Although suicide is a key issue and reducing suicide mortality is a global imperative, suicide is a highly complex biopsychosocial phenomenon, and in spite of several suicidal models developed in recent years and a high number of suicide risk factors identified, we still have neither a sufficient understanding of underpinnings of suicide nor adequate management strategies to reduce its prevalence. The present paper first overviews the background of suicidal behavior including its epidemiology, prevalence, age and gender correlations and its association with neuropsychiatric disorders as well as its clinical assessment. Then we give an overview of the etiological background, including its biopsychosocial contexts, genetics and neurobiology. Based on the above, we then provide a critical overview of the currently available intervention options to manage and reduce risk of suicide, including psychotherapeutic modalities, traditional medication classes also providing an up-to-date overview on the antisuicidal effects of lithium, as well as novel molecules such as esketamine and emerging medications and further molecules in development. Finally we give a critical overview on our current knowledge on using neuromodulatory and biological therapies, such as ECT, rTMS, tDCS and other options.

Functional and molecular characterization of suicidality factors using phenotypic and genome-wide data

Genome-wide association studies (GWAS) of suicidal thoughts and behaviors support the existence of genetic contributions. Continuous measures of psychiatric disorder symptom severity can sometimes model polygenic risk better than binarized definitions. We compared two severity measures of suicidal thoughts and behaviors at the molecular and functional levels using genome-wide data. We used summary association data from GWAS of four traits analyzed in 122,935 individuals of European ancestry: thought life was not worth living (TLNWL), thoughts of self-harm, actual self-harm, and attempted suicide. A new trait for suicidal thoughts and behaviors was constructed first, phenotypically, by aggregating the previous four traits (termed "suicidality") and second, genetically, by using genomic structural equation modeling (gSEM; termed S-factor). Suicidality and S-factor were compared using SNP-heritability (h2) estimates, genetic correlation (rg), partitioned h2, effect size distribution, transcriptomic correlations (ρGE) in the brain, and cross-population polygenic scoring (PGS). The S-factor had good model fit (χ2 = 0.21, AIC = 16.21, CFI = 1.00, SRMR = 0.024). Suicidality (h2 = 7.6%) had higher h2 than the S-factor (h2 = 2.54, Pdiff = 4.78 × 10-13). Although the S-factor had a larger number of non-null susceptibility loci (πc = 0.010), these loci had small effect sizes compared to those influencing suicidality (πc = 0.005, Pdiff = 0.045). The h2 of both traits was enriched for conserved biological pathways. The rg and ρGE support highly overlapping genetic and transcriptomic features between suicidality and the S-factor. PGS using European-ancestry SNP effect sizes strongly associated with TLNWL in Admixed Americans: Nagelkerke's R2 = 8.56%, P = 0.009 (PGSsuicidality) and Nagelkerke's R2 = 7.48%, P = 0.045 (PGSS-factor). An aggregate suicidality phenotype was statistically more heritable than the S-factor across all analyses and may be more informative for future genetic study designs interested in common genetic factors among different suicide related phenotypes.

Sex-Specific Genetic and Transcriptomic Liability to Neuroticism

BACKGROUND

The presentation, etiology, and relative risk of psychiatric disorders are strongly influenced by biological sex. Neuroticism is a transdiagnostic feature of psychiatric disorders displaying prominent sex differences. We performed genome-wide association studies of neuroticism separately in males and females to identify sex-specific genetic and transcriptomic profiles.

METHODS

Neuroticism scores were derived from the Eysenck Personality Inventory Neuroticism scale. Genome-wide association studies were performed in 145,669 females and 129,229 males from the UK Biobank considering autosomal and X chromosomal variation. Two-sided z tests were used to test for sex-specific effects of discovered loci, genetic correlates (n = 673 traits), tissue and gene transcriptomic profiles, and polygenic associations across health outcomes in the Vanderbilt University Biobank (39,692 females and 31,268 males).

RESULTS

The single nucleotide polymorphism heritability of neuroticism was not statistically different between males (h2 = 10.6%) and females (h2 = 11.85%). Four female-specific (rs10736549-CNTN5, rs6507056-ASXL3, rs2087182-MMS22L, and rs72995548-HSPB2) and 2 male-specific (rs10507274-MED13L and rs7984597) neuroticism risk loci reached genome-wide significance. Male- and female-specific neuroticism polygenic scores were most significantly associated with mood disorders (males: odds ratio = 1.11, p = 1.40 × 10-9; females: odds ratio = 1.14, p = 6.05 × 10-22). They also associated with sex-specific laboratory measurements related to erythrocyte count, distribution, and hemoglobin concentration. Gene expression variation in the pituitary was enriched for neuroticism loci in males (male: b = 0.026, p = .002), and genetically regulated transcriptomic changes highlighted the effect of SHISHA9, TEX26, and NCOA6.

CONCLUSIONS

Through a comprehensive assessment of genetic risk for neuroticism and the associated biological processes, this study identified several molecular pathways that can partially explain the known sex differences in neurotic symptoms and their psychiatric comorbidities.

Genetic differences between suicide deaths and deaths of undetermined intent

INTRODUCTION

Few, if any, prior studies have considered whether undetermined intent (UDI) deaths and suicide deaths differ with respect to genetic liability for suicidal behavior or psychopathology.

METHODS

The authors used Swedish national registry data to identify suicide deaths (N = 31,835) and UDI deaths (N = 10,623); sociodemographic covariates; and registrations for psychopathology. Family genetic risk scores (FGRS) were derived for each form of psychopathology. The authors used LASSO models to assess genetic and phenotypic differences across outcomes.

RESULTS

In the multivariate LASSO regressions, higher FGRS for major depression, bipolar disorder, and suicide death were associated with lower odds of UDI relative to unambiguous suicide (OR = 0.91-0.95), while those for alcohol and drug use disorders, ADHD, and criminal behavior were associated with higher odds of UDI relative to unambiguous suicide (OR = 1.04-1.12). When the corresponding phenotypic registration status for these outcomes was included in a subsequent model, the associations were attenuated and of small magnitude, but many remained different from OR = 1.

CONCLUSIONS

Aggregate genetic differences between unambiguous suicide decedents and UDI deaths are small, particularly when accounting for psychiatric comorbidity, but in some cases, statistically significant. These findings suggest that different analytic treatment of UDI deaths may be warranted depending on the research question. Replication in other samples, and using molecular genetic data, is necessary.

Unraveling the phenotypic and genomic background of behavioral plasticity and temperament in North American Angus cattle

BACKGROUND

Longitudinal records of temperament can be used for assessing behavioral plasticity, such as aptness to learn, memorize, or change behavioral responses based on affective state. In this study, we evaluated the phenotypic and genomic background of North American Angus cow temperament measured throughout their lifetime around the weaning season, including the development of a new indicator trait termed docility-based learning and behavioral plasticity. The analyses included 273,695 and 153,898 records for yearling (YT) and cow at weaning (CT) temperament, respectively, 723,248 animals in the pedigree, and 8784 genotyped animals. Both YT and CT were measured when the animal was loading into/exiting the chute. Moreover, CT was measured around the time in which the cow was separated from her calf. A random regression model fitting a first-order Legendre orthogonal polynomial was used to model the covariance structure of temperament and to assess the learning and behavioral plasticity (i.e., slope of the regression) of individual cows. This study provides, for the first time, a longitudinal perspective of the genetic and genomic mechanisms underlying temperament, learning, and behavioral plasticity in beef cattle.

RESULTS

CT measured across years is heritable (0.38-0.53). Positive and strong genetic correlations (0.91-1.00) were observed among all CT age-group pairs and between CT and YT (0.84). Over 90% of the candidate genes identified overlapped among CT age-groups and the estimated effect of genomic markers located within important candidate genes changed over time. A small but significant genetic component was observed for learning and behavioral plasticity (heritability = 0.02 ± 0.002). Various candidate genes were identified, revealing the polygenic nature of the traits evaluated. The pathways and candidate genes identified are associated with steroid and glucocorticoid hormones, development delay, cognitive development, and behavioral changes in cattle and other species.

CONCLUSIONS

Cow temperament is highly heritable and repeatable. The changes in temperament can be genetically improved by selecting animals with favorable learning and behavioral plasticity (i.e., habituation). Furthermore, the environment explains a large part of the variation in learning and behavioral plasticity, leading to opportunities to also improve the overall temperament by refining management practices. Moreover, behavioral plasticity offers opportunities to improve the long-term animal and handler welfare through habituation.

Genome-wide association study meta-analysis of suicide death and suicidal behavior

Suicide is a worldwide health crisis. We aimed to identify genetic risk variants associated with suicide death and suicidal behavior. Meta-analysis for suicide death was performed using 3765 cases from Utah and matching 6572 controls of European ancestry. Meta-analysis for suicidal behavior using data across five cohorts (n = 8315 cases and 256,478 psychiatric or populational controls of European ancestry) was also performed. One locus in neuroligin 1 (NLGN1) passing the genome-wide significance threshold for suicide death was identified (top SNP rs73182688, with p = 5.48 × 10^-8 before and p = 4.55 × 10^-8 after mtCOJO analysis conditioning on MDD to remove genetic effects on suicide mediated by MDD). Conditioning on suicidal attempts did not significantly change the association strength (p = 6.02 × 10^-8), suggesting suicide death specificity. NLGN1 encodes a member of a family of neuronal cell surface proteins. Members of this family act as splice site-specific ligands for beta-neurexins and may be involved in synaptogenesis. The NRXN-NLGN pathway was previously implicated in suicide, autism, and schizophrenia. We additionally identified ROBO2 and ZNF28 associations with suicidal behavior in the meta-analysis across five cohorts in gene-based association analysis using MAGMA. Lastly, we replicated two loci including variants near SOX5 and LOC101928519 associated with suicidal attempts identified in the ISGC and MVP meta-analysis using the independent FinnGen samples. Suicide death and suicidal behavior showed positive genetic correlations with depression, schizophrenia, pain, and suicidal attempt, and negative genetic correlation with educational attainment. These correlations remained significant after conditioning on depression, suggesting pleiotropic effects among these traits. Bidirectional generalized summary-data-based Mendelian randomization analysis suggests that genetic risk for the suicidal attempt and suicide death are both bi-directionally causal for MDD.

Risk of non-fatal suicide attempt in individuals with substance use disorder: the roles of aggregate genetic liability and environmental exposures in a Swedish population-based cohort

BACKGROUND AND AIMS

Substance use disorder (SUD) is related to widespread adverse consequences, including higher suicidality. Shared genetic liability has been demonstrated between SUD and suicidality. Here, we measured the factors that contribute to increased risk of non-fatal suicide attempt among individuals with SUD by focusing upon aggregate genetic risks and both childhood and past-year environmental factors.

DESIGN

Longitudinal study. Family genetic risk scores and environmental factors (childhood, aged from 0 to 15 years, and the year preceding SUD registration) were used to predict the relative risk of non-fatal suicide attempt using Cox proportional hazards models. Additional analyses employed a co-relative design, accounting for genetic factors and shared familial environment, to test for potential causality.

SETTING AND PARTICIPANTS

Based on longitudinal Swedish registry data, 228 617 individuals with SUD registrations from 1991 to 2015 were included.

MEASUREMENTS

SUD and suicide attempts were identified using medical records (International Classification of Diseases codes). SUD was also identified using pharmacy and criminal registries.

FINDINGS

In multivariable analyses that jointly accounted for all the selected potential predictors, individuals with SUD were at higher risk for non-fatal suicide attempt if they had experienced a parental death [hazard ratio (HR) = 1.58; 95% confidence interval (CI) = 1.30, 1.93], were female (HR = 1.53, 95% CI = 1.49, 1.57), had low educational attainment (HR = 1.50, 95% CI = 1.46, 1.55), received social welfare (HR = 1.21, 95% CI = 1.17, 1.25) or had lived in a non-intact family (HR = 1.11, 95% CI = 1.08, 1.14). In co-relative analyses, low education was supported as a possible causal factor for suicide attempt. Aggregate genetic risks interacted with low education and being raised in a non-intact family, with increased prevalence of suicide attempt in people with high genetic risks and unfavorable environmental exposures.

CONCLUSIONS

Aggregate genetic liability, childhood environmental experiences and specific socio-economic indicators are important risk factors for non-fatal suicide attempt among individuals with substance use disorder.

Genetics and epigenetics of self-injurious thoughts and behaviors: Systematic review of the suicide literature and methodological considerations

Suicide is a multifaceted and poorly understood clinical outcome, and there is an urgent need to advance research on its phenomenology and etiology. Epidemiological studies have demonstrated that suicidal behavior is heritable, suggesting that genetic and epigenetic information may serve as biomarkers for suicide risk. Here we systematically review the literature on genetic and epigenetic alterations observed in phenotypes across the full range of self-injurious thoughts and behaviors (SITB). We included 577 studies focused on genome-wide and epigenome-wide associations, candidate genes (SNP and methylation), noncoding RNAs, and histones. Convergence of specific genes is limited across units of analysis, although pathway-based analyses do indicate nervous system development and function and immunity/inflammation as potential underlying mechanisms of SITB. We provide suggestions for future work on the genetic and epigenetic correlates of SITB with a specific focus on measurement issues.

Suicidal ideation during adolescence: The roles of aggregate genetic liability for suicide attempts and negative life events in the past year

BACKGROUND

Suicidal thoughts and behaviors (STB) constitute a central public health concern in adolescence. Previous studies emphasized the difficulty to cope with negative life events during adolescence as a risk factor for STB. Familial and genetic liability has also been documented to explain STB risk. Nevertheless, less is known about aggregate genetic liability and its possible interaction with negative life events. Moreover, information is needed to understand how these factors differently affect STB in boys and girls.

METHODS

We evaluated suicidal ideation at 17 years old and examined the role of aggregate genetic liability, negative life events, and their interaction in a sample of 2,571 adolescents. Aggregate genetic liability was measured using a polygenic score (PGS) for suicide attempts. Negative life events were assessed in the past year and included parental divorce and hospitalizations, death of friends and relatives, bullying, failure-related events, and involvement with drugs. We conducted univariable and multivariable general linear models stratified by sex and evaluated the interactions between PGS and negative life events in subsequent models.

RESULTS

Analyses showed that suicidal ideation in boys is associated with failure to achieve something important (estimate = 0.198), bullying (estimate = 0.285), drug use (estimate = 0.325), and parental death (estimate = 0.923). In girls, both aggregate genetic liability (estimate = 0.041) and negative life events (failure at school [estimate = 0.120], failure to achieve something important [estimate = 0.279], drug use [estimate = 0.395], and bullying [estimate = 0.472]) were associated with suicidal ideation. Interaction analyses suggested that PGS interacted with drug use and failures at school, though this would need additional support.

CONCLUSIONS

These findings represent significant contributions to the fundamental understanding of STB in adolescence, suggesting to monitor the impact of negative life events during adolescence to better prevent suicide risk. Genetic liability is also of importance in girls and might influence the way they respond to environmental threats.

Cholecystokinin B receptor gene polymorphism (rs2941026) is associated with anxious personality and suicidal thoughts in a longitudinal study

OBJECTIVES

Cholecystokinin is a neuropeptide with a role in the neurobiology of adaptive behaviour that is implicated in anxiety disorders, while the underlying mechanisms currently remain insufficiently explained. The rs2941026 variation in the cholecystokinin B receptor gene has previously been associated with trait anxiety. Our aim was to investigate associations between the CCK_B receptor gene polymorphism rs2941026 with anxiety, personality, depressiveness and suicidality in a longitudinal study of late adolescence and early adulthood.

METHODS

We used reports on trait and state anxiety, depressiveness and suicidal thoughts, as well as Affective Neuroscience Personality Scales, from the two birth cohorts of the Estonian Children Personality, Behaviour and Health Study. We measured associations between the CCKBR gene rs2941026 and anxiety-related phenotypes both longitudinally and cross-sectionally at ages 15, 18, 25 and 33.

RESULTS

Homozygosity for both alleles of the CCKBR rs2941026 was associated with higher trait and state anxiety in the longitudinal analysis. Cross-sectional comparisons were statistically significant at ages 18 and 25 for trait anxiety and at ages 25 and 33 for state anxiety. Higher depressiveness and suicidal thoughts were associated with the A/A genotype at age 18. Additionally, homozygosity for the A-allele was related to higher FEAR and SADNESS in the Affective Neuroscience Personality Scales. The genotype effects were more apparent in females, who displayed higher levels of negative affect overall.

CONCLUSIONS

CCKBR genotype is persistently associated with negative affect in adolescence and young adulthood. The association of the CCKBR rs2941026 genotype with anxiety-related phenotypes is more pronounced in females.

Circulating miRNAs as Potential Biomarkers for Patient Stratification in Bipolar Disorder: A Combined Review and Data Mining Approach

Bipolar disorder is a debilitating psychiatric condition that is shaped in a concerted interplay between hereditary and triggering risk factors. Profound depression and mania define the disorder, but high clinical heterogeneity among patients complicates diagnosis as well as pharmacological intervention. Identification of peripheral biomarkers that capture the genomic response to the exposome may thus progress the development of personalized treatment. MicroRNAs (miRNAs) play a prominent role in of post-transcriptional gene regulation in the context of brain development and mental health. They are coordinately modulated by multifarious effectors, and alteration in their expression profile has been reported in a variety of psychiatric conditions. Intriguingly, miRNAs can be released from CNS cells and enter circulatory bio-fluids where they remain remarkably stable. Hence, peripheral circulatory miRNAs may act as bio-indicators for the combination of genetic risk, environmental exposure, and/or treatment response. Here we provide a comprehensive literature search and data mining approach that summarize current experimental evidence supporting the applicability of miRNAs for patient stratification in bipolar disorder.

Psychosocial moderators of polygenic risk for suicidal ideation: Results from a 7-year population-based, prospective cohort study of U.S. veterans

Polygenic risk scores (PRS) may help inform the etiology of suicidal thoughts and behaviors. In this study, we evaluated whether a suicidality PRS derived from a large genome-wide association study (GWAS) of suicidality from the UK Biobank (N = 122,935) predicted suicidal ideation (SI) in a 7-year population-based, prospective cohort of European-American US veterans (N = 1326). Results revealed that 8.8% (n = 115) of veterans developed new-onset SI, 4.0% (n = 52) had chronic SI, 3.4% (n = 31) had remitted SI, and 83.8% (n = 1128) denied SI over the study period. Suicidality PRS_standardized was positively associated with chronic SI (relative risk ratio [RRR] = 4.54, 95% confidence interval [CI] = 1.01-20.48) and new-onset SI (RRR = 2.97, 95%CI = 1.22-7.23), and negatively associated with remitted SI (RRR = 0.12, 95% CI = 0.02-0.60). Among veterans with higher suicidality PRS, those with higher baseline dispositional optimism had a lower likelihood of chronic SI (RRR = 0.67, 95% CI = 0.49-0.91) and higher likelihood of remitted SI (RRR = 1.98, 95% CI = 1.18-3.31). Among veterans with higher suicidality PRS, those with higher baseline levels of social support were less likely to develop new-onset SI (RRR = 0.95, 95% CI = 0.92-0.99). These interaction effects were enriched for genes implicated in neuron recognition and development, while the PRS main effect was enriched for genes involved in mannosylation. Collectively, results of this study suggest that suicidality PRS is linked prospectively to symptomatic courses of SI, and that dispositional optimism and social support moderate these associations. Interventions targeting these modifiable psychosocial factors may help mitigate risk of SI in veterans with high polygenic risk for suicidality.

What genes are differentially expressed in individuals with schizophrenia? A systematic review

Schizophrenia is a severe, complex mental disorder characterized by a combination of positive symptoms, negative symptoms, and impaired cognitive function. Schizophrenia is highly heritable (~80%) with multifactorial etiology and complex polygenic genetic architecture. Despite the large number of genetic variants associated with schizophrenia, few causal variants have been established. Gaining insight into the mechanistic influences of these genetic variants may facilitate our ability to apply these findings to prevention and treatment. Though there have been more than 300 studies of gene expression in schizophrenia over the past 15 years, none of the studies have yielded consistent evidence for specific genes that contribute to schizophrenia risk. The aim of this work is to conduct a systematic review and synthesis of case-control studies of genome-wide gene expression in schizophrenia. Comprehensive literature searches were completed in PubMed, EmBase, and Web of Science, and after a systematic review of the studies, data were extracted from those that met the following inclusion criteria: human case-control studies comparing the genome-wide transcriptome of individuals diagnosed with schizophrenia to healthy controls published between January 1, 2000 and June 30, 2020 in the English language. Genes differentially expressed in cases were extracted from these studies, and overlapping genes were compared to previous research findings from the genome-wide association, structural variation, and tissue-expression studies. The transcriptome-wide analysis identified different genes than those previously reported in genome-wide association, exome sequencing, and structural variation studies of schizophrenia. Only one gene, GBP2, was replicated in five studies. Previous work has shown that this gene may play a role in immune function in the etiology of schizophrenia, which in turn could have implications for risk profiling, prevention, and treatment. This review highlights the methodological inconsistencies that impede valid meta-analyses and synthesis across studies. Standardization of the use of covariates, gene nomenclature, and methods for reporting results could enhance our understanding of the potential mechanisms through which genes exert their influence on the etiology of schizophrenia. Although these results are promising, collaborative efforts with harmonization of methodology will facilitate the identification of the role of genes underlying schizophrenia.

Attachment Style Moderates Polygenic Risk for Posttraumatic Stress in United States Military Veterans: Results From the National Health and Resilience in Veterans Study

BACKGROUND

A polygenic risk score (PRS) derived from genome-wide association studies of posttraumatic stress disorder (PTSD) may inform risk for this disorder. To date, however, no known study has examined whether social environmental factors such as attachment style may moderate the relation between PRS and PTSD.

METHODS

We evaluated main and interactive effects of PRS and attachment style on PTSD symptoms in a nationally representative sample of trauma-exposed European-American U.S. military veterans (N = 2030). PRS was derived from a genome-wide association study of PTSD re-experiencing symptoms (N = 146,660) in the Million Veteran Program cohort. Using one-sample Mendelian randomization with data from the UK Biobank (N = 115,099), we evaluated the effects of re-experiencing PRS and attachment style on PTSD symptoms.

RESULTS

Higher re-experiencing PRS and secure attachment style were independently associated with PTSD symptoms. A significant PRS-by-attachment style interaction was also observed (β = -.11, p = .006), with a positive association between re-experiencing PRS and PTSD symptoms observed only among veterans with an insecure attachment style. One-sample Mendelian randomization analyses suggested that the association between PTSD symptoms and attachment style is bidirectional. PRS enrichment analyses revealed a significant interaction between attachment style and a variant mapping to the IGSF11 gene (rs151177743, p = 2.1 × 10^-7), which is implicated in regulating excitatory synaptic transmission and plasticity.

CONCLUSIONS

Attachment style may moderate polygenic risk for PTSD symptoms, and a novel locus implicated in synaptic transmission and plasticity may serve as a possible biological mediator of this association. These findings may help inform interpersonally oriented treatments for PTSD for individuals with high polygenic risk for this disorder.

Biobank Scale Pharmacogenomics Informs the Genetic Underpinnings of Simvastatin Use

Studying drug-metabolizing enzymes, encoded by pharmacogenes, may inform biological mechanisms underlying the diseases for which a medication is prescribed. Until recently, pharmacogenes could not be studied at biobank scale. In 7,649 unrelated African-ancestry (AFR) and 326,214 unrelated European-ancestry (EUR) participants from the UK Biobank, we associated pharmacogene haplotypes from 50 genes with 265 (EUR) and 17 (AFR) medication use phenotypes using generalized linear models. In EUR, N-acetyltransferase 2 (NAT2) metabolizer phenotype and activity score were associated with simvastatin use. The dose of NAT2*1 was associated with simvastatin use when compared with NAT2*5 (the most common haplotype). This association was robust to effects of low-density lipoprotein cholesterol (LDL-C) concentration (NAT2*1 odds ratio (OR) = 1.07, 95% CI: 1.05-1.09, P = 1.14 × 10^-8 ) and polygenic risk for LDL-C concentration (NAT2*1 OR = 1.09, 95% CI: 1.04-1.14, P = 2.26 × 10^-4 ). Interactive effects between NAT2*1 and simvastatin use on LDL-C concentration (OR = 0.957, 95% CI: 0.916-0.998, P = 0.045) were replicated in the electronic Medical Records and Genomics Pharmacogenetic Sequencing Pilot (eMERGE-PGx) cohort (OR = 0.987, 95% CI: 0.976-0.998, P = 0.029). We used biobank-scale data to uncover and replicate an association between NAT2 locus variation and better response to statin therapy. Testing NAT2 alleles may be useful for making clinical decisions regarding the potential benefit (e.g., absolute risk reduction) in LDL-C concentration prior to statin treatment.