The role of COMT gene Val108/158Met polymorphism in suicidal behavior: systematic review and updated meta-analysis

Genetic Variants Associated with Suicide Risk in the Mexican Population: A Systematic Literature Review

Suicide is defined as the action of harming oneself with the intention of dying. It is estimated that worldwide, one person dies by suicide every 40 s, making it a major health problem. Studies in families have suggested that suicide has a genetic component, so the search for genetic variants associated with suicidal behavior could be useful as potential biomarkers to identify people at risk of suicide. In Mexico, some studies of gene variants related to neurotransmission and other important pathways have been carried out and potential association of variants located in the following genes has been suggested: SLC6A4, SAT-1, TPH-2, ANKK1, GSHR, SCARA50, RGS10, STK33, COMT, and FKBP5. This systematic review shows the genetic studies conducted on the Mexican population. This article contributes by compiling the existing information on genetic variants and genes associated with suicidal behavior, in the future could be used as potential biomarkers to identify people at risk of suicide.

Genetic analysis of suicide: a sample study in Tuscany (Central Italy)

Many studies have examined the genetic contribution to suicide. However, data on suicide in the Italian population are scarce. We therefore aimed to address this gap by investigating a cohort of 111 Italians for whom a verdict of suicide had been declared in court in Florence, Italy between 2007 and 2017. This cohort included 86 men and 25 women. DNA samples were obtained from tissues or blood, and 22 genes from multiple neurobiological pathways previously shown to be associated with the pathogenesis of suicide were analysed. Next-generation sequencing was used to compare these gene sequences with those from a large, normal population. In this study, we identified 19 gene variants that were present at significantly lower frequencies in our Italian cohort than in the general population. In addition, four missense mutations were identified in four different genes: Monoamine Oxidase A (MAOA), 5-Hydroxytryptamine Receptor 2 A (HTR2A), Sodium Voltage-Gated Channel Alpha Subunit 8 (SCN8A), and Nitric Oxide Synthase 3 (NOS3). Our study identified several potential genetic links with suicide in a cohort of Italians and supports a relationship between specific genetic variants and suicidal behaviour in this population.

The roles of borderline personality disorder symptoms and dispositional capability for suicide in suicidal ideation and suicide attempts: Examination of the COMT Val158Met polymorphism

There is a need to identify the subset of individuals with borderline personality disorder (BPD) symptoms at greatest risk for transitioning from suicidal ideation to a suicide attempt. Contemporary models of suicide risk propose that the capability for suicide is necessary for moving from suicidal ideation to a suicide attempt. Few studies have examined dispositional capability factors for suicide, especially among individuals with BPD symptoms. One candidate may be the catechol-o-methyltransferase (COMT) Val158Met polymorphism given its influence on pain sensitivity and fear. This study examined the interactive relation of BPD symptoms and the COMT Val158Met polymorphism to suicidal ideation and suicide attempts. Fifty-nine treatment-seeking patients were recruited. Participants were administered a series of clinical interviews to evaluate BPD symptoms and suicidal thoughts and behaviors. Saliva samples were collected for genotyping. The relation between BPD symptoms and suicidal ideation was not influenced by the Val158Met polymorphism. However, among Val/Val carriers, the probability of a lifetime suicide attempt increased as BPD symptom severity increased. Findings provide preliminary support for the Val/Val variant as a dispositional factor that may increase risk for suicide attempts in BPD; however, results must be interpreted with caution until replication of findings occurs in larger samples.

Insights into S-adenosyl-l-methionine (SAM)-dependent methyltransferase related diseases and genetic polymorphisms

Enzymatic methylation catalyzed by methyltransferases has a significant impact on many human biochemical reactions. As the second most ubiquitous cofactor in humans, S-adenosyl-l-methionine (SAM or AdoMet) serves as a methyl donor for SAM-dependent methyltransferases (MTases), which transfer a methyl group to a nucleophilic acceptor such as O, As, N, S, or C as the byproduct. SAM-dependent methyltransferases can be grouped into different types based on the substrates. Here we systematically reviewed eight types of methyltransferases associated with human diseases. Catechol O-methyltransferase (COMT), As(III) S-adenosylmethionine methyltransferase (AS3MT), indolethylamine N-methyltransferase (INMT), phenylethanolamine N-methyltransferase (PNMT), histamine N-methyltransferase (HNMT), nicotinamide N-methyltransferase (NNMT), thiopurine S-methyltransferase (TPMT) and DNA methyltansferase (DNMT) are classic SAM-dependent MTases. Correlations between genotypes and disease susceptibility can be partially explained by genetic polymorphisms. The physiological function, substrate specificity, genetic variants and disease susceptibility associated with these eight SAM-dependent methyltransferases are discussed in this review.

SLC6A3 (DAT1) as a Novel Candidate Biomarker Gene for Suicidal Behavior

It has been previously shown that the serotonin and dopamine neurotransmitter systems might influence the predisposition to suicidal behavior. This study aims to estimate the contribution of 11 polymorphisms in the genes SLC6A4 (5HTT), HTR1A, HTR2A, HTR1B, SLC6A3 (DAT1), DRD4, DRD2, COMT, and BDNF to suicidal behavior and severity of symptoms of depression and anxiety in the Russian population. The study was performed on 100 patients with repeated suicide attempts and 154 controls. We first found an association between SLC6A3 (DAT1) 40 bp VNTR locus and suicidal behavior. This association was significant; when using the codominant (p = 0.006), dominant (p = 0.001), overdominant (p = 0.004), and log-additive (p = 0.004) models, LL genotype played a protective role (OR = 0.48, 0.29–0.82, p = 0.005). Difference in the distribution of COMT rs4680 genotypes was significant in the codominant (p = 0.04), dominant (p = 0.013), and log-additive (p = 0.02) models, and AA genotype might protect against suicide (OR = 0.49, 0.26–0.91, p = 0.025). SLC6A4 5-HTTLPR + rs25531 locus was significant in the recessive model (p = 0.024), and also affected the severity of symptoms of depression (p = 0.044) and personal anxiety (p = 0.029). Our results suggest that allelic variants of SLC6A3, COMT, and SLC6A4 genes might be considered as risk factors for suicidal attempts.

Suicidal ideation and aggression in childhood, genetic variation and young adult depression

BACKGROUND

Suicidal thoughts and behaviors have been studied in association with a variety of risk factors. The aim of the present study was to determine if levels of child/adolescent aggression and/or variation in candidate genes previously associated with suicidal behaviors in adults would influence the presence of suicidal ideation in childhood/adolescence, and to determine if ideation was associated with young adult depression.

METHODS

A longitudinal study of children, adolescents and young adults who were at high or low risk for alcohol and other substance use disorders by familial background were assessed. The Child Behavior Checklist (CBCL) aggression scale scores with derived subtypes (physical and relational) and genetic variation (ANKK1, DRD2, COMT, SLC6A4, HTR2C) were used as predictors of the presence and onset of suicidal ideation in childhood using survival analysis. Structural equation models (SEM) were fit to determine the relative importance of the predictors controlling for background variables.

RESULTS

CBCL aggression was significantly associated with child/adolescent suicidal ideation. One SNP in the ANKK1 gene (rs1800497), one in the HTR2C gene (rs6318), and two haplotypes, AAAC in the ANKK1-DRD2 complex and the CCC haplotype of the HTR2C gene, were significantly associated with the presence and onset of child/adolescent suicidal ideation. Follow up in young adulthood showed a significant relationship between suicidal ideation in childhood/adolescence and young adult depression.

CONCLUSIONS

Genetic variation and presence of elevated aggression scores from the childhood CBCL are significant predictors of childhood suicidal ideation. Suicidal ideation in childhood and being female are predictors of young adult depression.

Catechol-O-Methyltransferase Gene Polymorphisms and the Risk of Chemotherapy-Induced Prospective Memory Impairment in Breast Cancer Patients with Varying Tumor Hormonal Receptor Expression

Background

Existing research evidence indicates that breast cancer patients have different degrees of cognitive dysfunction after chemotherapy, and polymorphisms in 3 genes (catechol-O-methyltransferase, COMT; apolipoprotein E, APOE; and brain-derived neurotrophic factor, BDNF) have been associated with cognitive impairment. However, the role of these 3 gene polymorphisms in modulating cognitive impairment in breast cancer survivors with varying hormonal receptor expression is not clear at present.

To explore the effects of genetic polymorphisms in BDNF, APOE, and COMT on the regulation of prospective memory impairments induced by chemotherapy in breast cancer patients with various expression levels of estrogen receptor (ER) and progesterone receptor (PR).

Material/Methods

A total of 232 patients with breast cancer (113 with ER−/PR− and 119 with ER+/PR+) were evaluated before and after chemotherapy for cognitive function, including prospective memory. Following previously published sequencing procedures, we assessed 6 single-nucleotide polymorphisms (SNPs), including BDNF (rs6265), APOE (rs429358, rs7412), and COMT (rs165599, rs4680, rs737865).

Results

The patients showed poorer prospective memory scores after chemotherapy than before chemotherapy. Furthermore, the ER−/PR− group showed poorer event-based prospective memory (EBPM) scores than the ER+/PR+ group (z=−7.831, p<0.01) after chemotherapy. The patients with the COMT rs737865G/G genotype, compared with those with the A/A and A/G genotypes, showed a linear EBPM performance (β=1.499, 95% confidence interval (CI)=1.017~2.211) and were less likely to have memory impairment. In contrast, APOE and BDNF polymorphisms did not influence cognitive performance.

Conclusions

The patterns of hormonal receptor expression may be related to prospective memory impairments induced by chemotherapy in breast cancer patients. Furthermore, the COMT polymorphism (rs737865) was linearly related to the extent of deficits in EBPM and may represent a potential genetic marker of risk for cognitive deficits triggered by chemotherapy in patients with breast cancer.

Association between COMT gene Val108/158Met and antidepressive treatment response: A meta-analysis

Multiple antidepressive treatment methods are widely used in the clinic, but different patients showed considerable differences in response to the same treatment. The catechol-O-methyltransferase (COMT) rs4680 polymorphism is involved in the antidepressive treatment reaction; however, the results in different studies are inconsistent. Thus, we performed a meta-analysis to explore the association of the COMT rs4680 polymorphism with the treatment response in major depressive disorder (MDD) patients. An online search was performed through PubMed, EMBASE and the Cochrane library up to December 2018. The odds ratios (ORs), 95% confidence intervals (95% CI) and heterogeneity were calculated in four genetic models. Subgroup analysis and Galbraith plot were carried out to detect the potential source of heterogeneity. Sensitivity and publication bias analyses were performed to identify the reliability of the results. A total of 11 studies involving 2845 individuals were included in this meta-analysis. The results of the subgroup analysis indicated that patients who carried the G allele had remission or a better response to electroconvulsive therapy (ECT) in four genetic models. Excluding the studies that might lead to heterogeneity, overall ORs were recalculated, and no obvious association between rs4680 polymorphism and therapeutic reaction was detected in the allelic, recessive and additive models. In the dominant model, COMT rs4680 variants showed significant associations with antidepressive treatment, but the result was highly dependent on the individual study. In addition, the patients with the GG or AG + GG genotype in comparison to AA were associated with a better response to ECT treatment. However, due to the small number of studies using ECT treatment, we suggest that more research should be performed to verify this result.

Systems pharmacogenomics - gene, disease, drug and placebo interactions: a case study in COMT

Disease, drugs and the placebos used as comparators are inextricably linked in the methodology of the double-blind, randomized controlled trial. Nonetheless, pharmacogenomics, the study of how individuals respond to drugs based on genetic substrate, focuses primarily on the link between genes and drugs, while the link between genes and disease is often overlooked and the link between genes and placebos is largely ignored. Herein, we use the example of the enzyme catechol-O-methyltransferase to examine the hypothesis that genes can function as pharmacogenomic hubs across system-wide regulatory processes that, if perturbed in andomized controlled trials, can have primary and combinatorial effects on drug and placebo responses.