Study on genes of the serotonergic system and suicidal behavior: protocol for a case-control study in Mexican population

The Relationship Between CYP46A1 Polymorphism and Suicide Risk: A Preliminary Investigation

Suicide is a global public health issue, with a particularly high incidence in individuals suffering from Major Depressive Disorder (MDD). The role of cholesterol in suicide risk remains controversial, prompting investigations into genetic markers that may be implicated. This study examines the association between CYP46A1 polymorphisms, specifically SNPs rs754203 and rs4900442, and suicide risk in a Mexican MDD patient cohort. Our study involved 188 unrelated suicide death victims, 126 MDD patients, and 144 non-suicidal controls. Genotypic and allelic frequencies were assessed using the Real Time-polymerase chain reaction method, and associations with suicide risk were evaluated using chi-square tests. The study revealed significant differences in allelic and genotypic frequencies in rs754203 SNP between suicide death and controls. The CYP46A1 rs754203 genotype G/G was significantly linked with suicide, and the G allele was associated with a higher risk of suicide (OR = 1.370, 95% CI = 1.002-1.873). However, we did not observe any significant differences in genotype distribution or allele frequencies of CYP46A1 rs4900442. Our study suggests that carriers of the CYP46A1 rs754203 G allele (A/G + G/G) may play a role in suicidal behavior, especially in males. Our findings support that the CYP46A1 gene may be involved in susceptibility to suicide, which has not been investigated previously. These results underscore the importance of further research in different populations to elucidate the genetic underpinnings of the role of CYP46A1 in suicide risk and to develop targeted interventions for at-risk populations.

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.

Comparisons between protocols and publications of case-control studies: analysis of potential causes of non-reproducibility and recommendations for enhancing the quality of personalization in healthcare

Background

Selective reporting of results in published case-control studies has been widely suspected, but little comprehensive information on selective reporting is available with regard to case-control studies. We aimed to evaluate the concordance of findings between publications and the protocols of case-control studies and to assess the level of selective reporting of results in case-control studies.

Methods

The databases of Embase, Medline, Scopus, and Web of Science were searched to identify case-control study protocols published between January 1, 1990 and December 31, 2017. The numbers and characteristics of predefined exposures (or factors) were extracted from the protocols. The reported and unreported factors were both collected from the published studies and protocols. The frequency of selective reporting of results were estimated by identifying the discrepancies of factors between the protocols and the published studies. Study sample size and the extent of selective reporting of factors were measured by a Spearman correlation analysis.

Results

Fourteen protocols with 24 published studies and 159 factors were identified, of which eight protocols (57.1%) had discrepancies between the publications and protocols. The prevalence of incomplete reporting in published case-control studies was 42.9% (6/14), with participant characteristics, anthropometric and laboratory measurement variables more likely to be unreported. A total of 16,835 cases and 56,049 controls were recruited in the 14 protocols of case-control studies (sample size ranges from 428 to 52,596 per study). Sample size had no statistical significance with selective reporting of results (P > 0.05).

Conclusion

The study protocols should be publicly available prior to the completion of case-control studies so that the potential bias can be assessed by the readers. Our findings highlight the need for investigators, peer reviewers, and readers to exercise increased awareness and scrutiny due to the undesirable practice of selective reporting of results in medical sciences causing the loss of potentially important information, thus impacting quality of personalized attitude in healthcare in the context of the predictive, preventive, and personalized medicine.

Prioritization and comprehensive analysis of genes related to major depressive disorder

Background

Major depressive disorder (MDD) is a serious mental health problem in modern society, which is difficult to identify and diagnose in the early stages. Despite strong evidence supporting the heritability of MDD, progresses in large‐scale and individual genetic studies remain preliminary.

Methods

In this study, a multi‐data source‐based prioritization (MDSP) method was proposed, and an appropriate threshold was determined for the optimization of depression‐related genes (DEPgenes). Analyses on Gene Ontology biological processes, KEGG pathway and the specific pathway crosstalk network were further proposed.

Results

A total of 143 DEPgenes were identified and the MDD‐specific network was constructed for the pathogenesis investigation and therapeutic methods development of MDD. Comparing with existing research strategies, the genetic optimization and analysis results were confirmed to be reliable. Finally, the pathway enrichment and crosstalk analyses revealed two unique pathway interaction modules that were significantly enriched with MDD genes. The related core pathways of neuroactive ligand‐receptor interaction and dopaminergic synapse supported the neuropathology hypothesis of MDD. And the pathways of serotonergic synapse and morphine addiction indicated the mechanism of drug addiction caused by serotonin used in the treatment.

Conclusions

This work provided a reference for the study of MDD, although future validation by extensive experimentation is still required.

The Frontiers of Suicide

Suicide is a serious public health problem in many countries and has always been a source of apprehension and quest to human mankind, which can be resolved with due diligence. Suicide is a hidden and silent epidemic, with many causative factors. Studying and researching on various causative factors have always been the subject of significance for the researchers. Psychiatric illnesses happen to be the primary reasons for the majority of suicide mortality cases. Not only this, there has been a consistent increase in the no. of cases of mental disorders as well as attempted and completed suicide cases. If one looks at global scenario, an approximate 70,000 people commit suicide, and further alarming is the fact that the rate of suicide attempt cases has gone up to 250% during last 18 years in conflict zones. Poisoning, hanging and self-immolation are some of the common methods to commit suicide. Physical and mental illness, disturbed emotional relationships and economic difficulties were the major reasons for suicide with the predisposed population being women, student and farmers. As per WHO's approximation, there is one suicide every minute and an attempted suicide every third second. It implies that the number of killed due to suicide is greater than that of the ones killed due to the armed conflict.

Association between serotonin 2C receptor gene (HTR2C) polymorphisms and psychopathological symptoms in children and adolescents

Serotonin 2C receptors (5HT2C) are involved in serotonin-driven dynamic equilibrium adjustments responsible for homeostatic stability in brain structures that modulate behavior and emotions. Single nucleotide polymorphisms (SNPs) from the serotonin 2C receptor gene (HTR2C) have been associated with several neurological and mental disorders, including abnormalities in cognitive and emotional processes. The aim of this study was to evaluate the association between the rs6318 SNP of the HTR2C gene and behavioral characteristics exhibited by children and adolescents based on the Child Behavior Checklist (CBCL/6-18) inventory. Eighty-five psychiatric outpatients between 8 and 18 years of age underwent genotyping of the rs6318 SNP. The CBCL/6-18 scale was administered to their caregivers. The chi-squared test was used to assess differences in the frequency of C and G alleles of the rs6318 SNP relative to the grouped CBCL/6-18 scores; significance level was 5%. The presence of the G allele of rs6318 was found to be associated with characteristics of aggressive behavior and social problems, and aggressive behavior was found to be associated with heterozygosis in females. These findings contribute to the identification of mental and behavioral phenotypes associated with gene expression.

Exploring the risk factors contributing to suicide attempt among adolescents: A qualitative study

BACKGROUND

Since suicide attempt among adolescents is a major challenge and the reasons why this age group attempt suicide are complex, the aim of this study was to investigate the risk factors that contribute to suicide attempt among adolescents.

MATERIALS AND METHODS

In this qualitative content analysis, 14 adolescents (12-19 years old) who were admitted in two hospitals in Shiraz, Iran, were interviewed. Participants who tried attempt suicide with medication were selected by purposive sampling and the data were gathered by semi-structured interviews. Data analysis was guided by the conventional approach of qualitative content analysis.

RESULTS

Three major themes and 13 subthemes emerged from data analysis. The main themes were: (a) Individual factors and experiences (psycho-emotional problems, puberty, religious beliefs, stress management strategies, marriage and love, field and level of education); (b) family factors (family structure, family relationship, family economic features, family health conditions); and (c) social factors (suicidal behavior in others, media influence, professional support).

CONCLUSIONS

This study identified three major themes related to suicide attempt among adolescents in the context. As a result, suicide prevention and care provision should formulate a comprehensive method, considering the interaction of medical besides individual, familiar, and social factors in their assessment and care provision.

Differences Between Patients that Made an Impulsive or Premeditated Suicide Attempt in a Mexican Population

OBJECTIVE

We performed a study to identify differences between patients with impulsive suicide attempt and those with premeditated suicide attempt in a Mexican population.

METHOD

We studied 144 patients who recently attempted suicide. Impulsive and premeditated suicide attempts were evaluated with the Suicide Intent Scale. These data were divided according to the type of attempt. Subsequently, the characteristics between the two groups were compared.

RESULTS

The rate of patients that made an impulsive attempt was 61.8% and only 9.7% of the patients carried out a premeditated suicide attempt. More years of schooling/education and less severity of the attempt were observed in patients that carried out an impulsive suicide attempt (p < 0.001). Alcohol consumption (0.003) and use of cannabis (0.002) were present in patients who premeditated a suicide attempt.

CONCLUSIONS

Our findings demonstrate that there are clinical differences among the individuals who carried out an impulsive suicide attempt from those who premeditated an attempt in a Mexican population. As a result, when planning interventions and prevention efforts it may be helpful to consider these clinical differences and demographic characteristics.

Gender differences in socio-demographic, clinical characteristics and psychiatric diagnosis in/of suicide attempters in a Mexican population

OBJECTIVE

The aim of the present study was to analyse demographic and clinical characteristics, as well as psychiatric diagnoses to identify gender differences in patients with attempted suicide in a Mexican population.

METHODS

Between September 2010 and September 2012, 140 suicide attempts were documented in the Department of Psychiatry at the General Hospital of Comalcalco (Hospital General de Comalcalco in Spanish) in Tabasco, Mexico. Diagnoses were established using the DSM-IV questionnaire in which Axis I and II were considered. The Suicide Intent Scale was also applied.

RESULTS

In our sample, 63.6% were females and 36.4% males. With regard to socio-demographic characteristics, the predominant marital status in males was single, and in females married (χ2=5.93, df=2, p=0.05). In occupation the male group was mainly unemployed and housewife in females (χ2=55.51, df=4, p<0.001). Male subjects were more likely to consume alcohol (χ2=20.40, df=1, p≤0.001), cannabis (χ2=16.62, df=1, p≤0.001) or tobacco. The prevalence of psychiatric diagnosis was significantly different because, the male group was mainly diagnosed with substance-related disorders, whereas female participants showed a prevalence of stress-related disorders (χ2=34.17, gl=4, p=0.0001).

CONCLUSION

Our results provide evidence that the characteristics of suicide attempt are different by gender in the Mexican population. Interventions are necessary for the development of prevention strategies that may lead to a reduction in suicidal behaviour. These preventive activities should consider the occupation for the female group and consumption of alcohol, cannabis or tobacco in the male group.

Association between HTR2C gene variants and suicidal behaviour: a protocol for the systematic review and meta-analysis of genetic studies

INTRODUCTION

Suicide is an important public health problem and one of the most common causes of death throughout the world. Suicidal behaviour is complex, and its causes are multifactorial. Case-control studies have reported an association between an alteration of the serotonin system and suicidal behaviour. Recently, it has been suggested that the 5-HTRC2 serotonin receptor gene is involved in the pathogenesis of suicidal behaviour.

METHODS AND ANALYSIS

To evaluate the role of the 5-HTR2C gene in suicidal behaviour, we will perform a systematic review and a meta-analysis of worldwide reports that have investigated the association between the serotonin system and suicidal behaviour. This analysis will be reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Studies deemed fit for inclusion in the systematic review will be scored for methodological quality using the Newcastle-Ottawa Assessment Scale (NOS). The inclusion criteria will be to present independent data, to be case-control studies and to be published in journal peer reviews. To generate more accurate analyses, we will grade the reports using the GRADES scale procedures.

ETHICS AND DISSEMINATION

This study will describe the association between the HTR2C gene and suicidal behaviour. The results will be reported in a peer-reviewed publication and in scientific presentations in Mexico and throughout the world.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42014009213.