Multiple tissue methylation analysis of HTR2A exon I in suicidal behavior

Mediation of DNA methylation (cg04622888 and cg05037505) in the association between childhood maltreatment and non-suicidal self-injury in early adolescents

It is unclear whether DNA methylation underlies the association between childhood maltreatment (CM) and non-suicidal self-injury (NSSI) in early adolescents. We aim to explore the mediation of specific DNA methylation sites in the associations of CM and its subtypes with NSSI, following investigation on the association between specific DNA methylation sites and NSSI. A case-control study was conducted to examine 155 adolescents aged 12-14 years who were identified to have engaged in NSSI and 201 controls. CM and its subtypes were evaluated by using the Childhood Trauma Questionnaire. The EPIC 850 k Bead Chip was used to discover differential methylation sites (DMSs) in the peripheral blood between 10 NSSI cases and 10 controls. Targeted pyrosequencing was employed to detect the levels of specific DMSs among the total study population, which were selected based on bioinformatics analyses and literature review. We discovered 456 DMSs between NSSI cases and controls, 219 were hypermethylated and 237 were hypomethylated. After controlling for potential confounders, CM or its subtypes, and the methylation of cg04622888 and cg05037505 were all significantly associated with NSSI (all P < 0.05). The total association of CM and its subtypes with NSSI were all significantly (all P < 0.05), with the standardized coefficient (β) ranged from 0.12 for physical neglect to 0.24 for emotional neglect and CM. Significant indirect association of physical neglect with NSSI through methylation of cg04622888 was observed and the mediating proportion was 0.14 (95%CI 0.06-0.23). Significant indirect associations of emotional abuse, emotional neglect, and physical neglect with NSSI through methylation of cg05037505 were also observed, and the mediating proportions were 0.09 (95%CI 0.04-0.14), 0.08 (95%CI, 0.03-0.14) and 0.19 (95%CI 0.07-0.32), respectively. Data of this study suggested that methylation of cg04622888 and cg05037505 were independently associated with NSSI among early adolescents, and they partially mediated the associations of emotional abuse, emotional neglect, and physical abuse with NSSI.

Genetics of suicide ideation. A role for inflammation and neuroplasticity?

Suicide is a leading cause of death worldwide. Suicide ideation (SI) is a known risk factor for suicide behaviour (SB). The current psychobiology and genetic predisposition to SI and SB are poorly defined. Despite convincing relevance of a genetic background for SI, there is no current implementable knowledge about the genetic makeup that identifies subjects at risk for it. One of the possible reasons for the absence of a clear-cut evidence is the polygenetic nature of SI along with the very large sample sizes that are needed to observe significant genetic association result. The CATIE sample was instrumental to the analysis. SI was retrieved as measured by the Calgary test. Clinical possible covariates were identified by a nested regression model. A principal component analysis helped in defining the possible genetic stratification factors. A GWAS analysis, polygenic risk score associated with a random forest analysis and a molecular pathway analysis were undertaken to identify the genetic contribution to SI. As a result, 741 Schizophrenic individuals from the CATIE were available for the genetic analysis, including 166,325 SNPs after quality control and pruning. No GWAS significant result was found. The random forest analysis conducted by combining the polygenic risk score and several clinical variables resulted in a possibly overfitting model (OOB error rate < 1%). The molecular pathway analysis revealed several molecular pathways possibly involved in SI, of which those involved in microglia functioning were of particular interest. A medium-small sample of SKZ individuals was analyzed to shed a light on the genetic of SI. As an expected result from the underpowered sample, no GWAS positive result was retrieved, but the molecular pathway analysis indicated a possible role of microglia and neurodevelopment in SI.

Epigenetic studies in suicidal ideation and behavior

Most psychiatric disorders are associated with an elevated risk of suicide. Suicidal behavior is the product of the interaction of many risk factors, such as genetics and environmental factors. Hence, epigenetics research may help to understand the mechanisms leading to suicidal ideation and behavior. This review will discuss epigenetic studies in both suicidal ideation and behavior. Epigenetic modifications are likely to be important in both suicidal ideation and behavior. Most of the reviewed studies found significant epigenetic modifications linked with suicidal behavior rather than ideation. Although sizable research has been carried out on this topic, most studies have been done on small-scale samples, and future research is required in larger samples with better clinical characterization of suicide phenotypes to investigate these epigenetic modifications further.

Epigenetic marks in suicide: a review

Suicide is a complex phenomenon and a global public health problem that involves several biological factors that could contribute to the pathophysiology of suicide. There is evidence that epigenetic factors influence some psychiatric disorders, suggesting a predisposition to suicide or suicidal behavior. Here, we review studies of molecular mechanisms of suicide in an epigenetic perspective in the postmortem brain of suicide completers and peripheral blood cells of suicide attempters. Besides, we include studies of gene-specific DNA methylation, epigenome-wide association, histone modification, and interfering RNAs as epigenetic factors. This review provides an overview of the epigenetic mechanisms described in different biological systems related to suicide, contributing to an understanding of the genetic regulation in suicide. We conclude that epigenetic marks are potential biomarkers in suicide, and they could become attractive therapeutic targets due to their reversibility and importance in regulating gene expression.

Suicide epigenetics, a review of recent progress

BACKGROUND

Suicide results in over 800,000 deaths every year, making it a major public health concern worldwide. It is highly complex, with genetic and environmental influences. Epigenetic mechanisms, including DNA methylation, miRNA, and histone modifications, could explain the complex interplay of environmental risk factors with genetic risk factors in the emergence of suicidal behavior.

METHODS

Here, we review the literature on suicide epigenetics over the past 10 years.

RESULTS

There has been significant progress in the field of suicide epigenetics, with emerging findings in the brain-derived neurotrophic factor and hypothalamic-pituitary-adrenal axis genes.

LIMITATIONS

Studying patient subgroups is needed in order to extract more comparable and reproducible epigenetic findings in suicide.

CONCLUSIONS

It is crucial to consider suicidal patients or suicide victims' distal and proximal past history e.g., early-life adversity and psychiatric disorder in epigenetic studies of suicidality.

The Role of Epigenetic Dysregulation in Suicidal Behaviors

Suicidal behaviors have been associated with both heritable genetic variables and environmental risk factors. Epigenetic processes, such as DNA methylation, have important roles in mediating the effects of the environment on behavior. Dysregulation of these processes has been observed in many psychiatric disorders, and evidence suggests that they may also be involved in suicidal behaviors. Herein, we have summarized candidate gene and epigenome-wide studies which have investigated DNA methylation in relation to suicidal behaviors, as well as discussed some of the limitations of the field to date.