Genetic association analysis of 5-HTR2A gene variants in eating disorders in a Mexican population

Genetic polymorphisms and their association with neurobiological and psychological factors in anorexia nervosa: a systematic review

Background and aims

Anorexia nervosa (AN) is a complex neuropsychiatric disorder. This systematic review synthesizes evidence from diverse studies to assess and investigate the association between gene polymorphisms and psychological and neurobiological factors in patients with AN.

Methods

A systematic search across PubMed, PsycINFO, Scopus, and Web of Science databases, along with manual searching, was conducted. The review protocol was approved by PROSPERO (CRD42023452548). Out of 1,250 articles, 11 met the inclusion criteria. The quality of eligible articles was assessed using the Newcastle-Ottawa Scale (NOS) tool. The systematic review followed the PRISMA guidelines.

Results

The serotoninergic system, particularly the 5-HTTLPR polymorphism, is consistently linked to altered connectivity in the ventral attention network, impaired inhibitory control, and increased susceptibility to AN. The 5-HTTLPR polymorphism affects reward processing, motivation, reasoning, working memory, inhibition, and outcome prediction in patients with AN. The dopaminergic system, involving genes like COMT, DRD2, DRD3, and DAT1, regulates reward, motivation, and decision-making. Genetic variations in these dopaminergic genes are associated with psychological manifestations and clinical severity in patients with AN. Across populations, the Val66Met polymorphism in the BDNF gene influences personality traits, eating behaviors, and emotional responses. Genes like OXTR, TFAP2B, and KCTD15 are linked to social cognition, emotional processing, body image concerns, and personality dimensions in patients with AN.

Conclusion

There was an association linking multiple genes to the susceptibly and/or severity of AN. This genetic factor contributes to the complexity of AN and leads to higher diversity of its clinical presentation. Therefore, conducting more extensive research to elucidate the underlying mechanisms of anorexia nervosa pathology is imperative for advancing our understanding and potentially developing targeted therapeutic interventions for the disorder.Systematic review registration: [https://clinicaltrials.gov/], identifier [CRD42023452548].

Association of serotonin receptor gene polymorphisms with anorexia nervosa: a systematic review and meta-analysis

PURPOSE

Several studies have investigated the association between anorexia nervosa and polymorphisms of genes regulating serotonin neurotransmission, with a focus on the rs6311 polymorphism of 5-HTR2A. However, inconsistent results of these studies and conflicting conclusions of existing meta-analyses complicate the understanding of a possible association. We have updated these results and evaluated the involvement of other serotonin receptor gene polymorphisms in anorexia nervosa.

METHODS

Adhering to PRISMA guidelines, we have searched studies on anorexia nervosa and serotonin-regulating genes published from 1997 to 2022, selected those concerning receptor genes and meta-analyzed the results from twenty candidate gene studies on the 5-HTR2A rs6311 polymorphism and the 5-HTR2C rs6318 polymorphism.

RESULTS

Present analyses reveal an association for the 5-HTR2A rs6311 polymorphism, with G and A alleles, across eighteen studies (2049 patients, 2877 controls; A vs. G allele, Odds Ratio = 1.24; 95% Confidence Interval = 1.06-1.47; p = 0.009). However, after geographic subgrouping, an association emerged only in a Southern European area, involving five studies (722 patients, 773 controls; A vs. G allele, Odds Ratio = 1.82; 95% Confidence Interval = 1.41-2.37; p < 0.00001). No association was observed for the 5-HTR2C rs6318 polymorphism across three studies.

CONCLUSIONS

To date, the involvement in the pathophysiology of anorexia nervosa of the 5-HTR2A rs6311 polymorphism appears limited to a specific genetic and/or environmental context, while that of the 5-HTR2C rs6318 polymorphism seems excluded. Genome-wide association studies and epigenetic studies will likely offer deeper insights of genetic and environmental factors possibly contributing to the disorder.

LEVEL OF EVIDENCE

III Evidence obtained from well-designed cohort or case-control analytic studies. Clinical trial registration PROSPERO registration number: CRD42021246122.

The contribution of the 5-hydroxytryptamine receptor 2 A gene polymorphisms rs6311 and rs6313 to Schizophrenia in Iran

OBJECTIVE

Schizophrenia is an acute mental disorder with an undefined etiology. Its high heritability suggests that several genetic variants and polymorphisms may contribute to the severity and emergence of its symptoms. Former molecular evidence has shed some light on the association of serotonergic pathway genetic polymorphisms with schizophrenia. This study aimed to investigate the association between schizophrenia and two SNPs from one haplotype block, which lies in the 5-hydroxytryptamine receptor 2 A (5-HTR2A) gene in the Iranian population.

MATERIAL AND METHODS

Blood samples were collected from one-hundred and fifty-two patients diagnosed with schizophrenia and one-hundred and fifty-eight cases of the healthy control, who were matched in terms of age and gender. The participants were genotyped for rs6311 and rs6313 using PCR-RFLP. R programming language and Haploview software were respectively leveraged for statistical and haplotype inferencing.

RESULTS

The results showed that there was no significant association between rs6313 and schizophrenia. However, the rs6311 T allele was independently associated with schizophrenia, and it was significantly associated with SCZ in an rs6311-rs6313 haplotype. Moreover, the general linear model confirmed the potential predictor role of rs6311 for schizophrenia and the C allele of rs6313 demonstrated a higher frequency among females compared to males.

CONCLUSION

The findings of this study indicated the association of rs6311 and rs6311-rs6313 haplotype with schizophrenia in the Iranian population and also suggested a potential schizophrenia risk predictor role for rs6311.

The serotonin receptor 5-HT2A modulates lifespan and protein feeding in Drosophila melanogaster

The conserved neurotransmitter serotonin has been shown to be an important modulator of lifespan in specific nutritional contexts; however, it remained unclear how serotonin signaling influences lifespan under normal conditions. Here, we show that serotonin signaling through the 5-HT2A receptor influences lifespan, behavior, and physiology in Drosophila. Loss of the 5-HT2A receptor extends lifespan and induces a resistance to changes in dietary protein that are normally detrimental to lifespan. 5-HT2A ^-/- null mutant flies also display decreased protein feeding and protein content in the body. Therefore, serotonin signaling through receptor 5-HT2A is likely recruited to promote motivation for protein intake, and chronic reduction of protein-drive through loss of 5-HT2A signaling leads to a lower protein set-point adaptation, which influences physiology, decreases feeding, and increases lifespan. Our findings reveal insights into the mechanisms by which organisms physiologically adapt in response to perceived inability to satisfy demand.

A Systematic Review of Genetic Polymorphisms Associated with Binge Eating Disorder

The genetic polymorphisms involved in the physiopathology of binge eating disorder (BED) are currently unclear. This systematic review aims to highlight and summarize the research on polymorphisms that is conducted in the BED. We looked for observational studies where there was a genetic comparison between adults with BED, in some cases also with obesity or overweight, and healthy controls or obesity/overweight without BED. Our protocol was written using PRISMA. It is registered at PROSPERO (identification: CRD42020198645). To identify potentially relevant documents, the following bibliographic databases were searched without a time limit, but until September 2020: PubMed, PsycINFO, Scopus, and Web of Science. In total, 21 articles were included in the qualitative analysis of the systematic review, as they met the eligibility criteria. Within the selected studies, 41 polymorphisms of 17 genes were assessed. Overall, this systematic review provides a list of potentially useful genetic polymorphisms involved in BED: 5-HTTLPR (5-HTT), Taq1A (ANKK1/DRD2), A118G (OPRM1), C957T (DRD2), rs2283265 (DRD2), Val158Met (COMT), rs6198 (GR), Val103Ile (MC4R), Ile251Leu (MC4R), rs6265 (BNDF), and Leu72Met (GHRL). It is important to emphasize that Taq1A is the polymorphism that showed, in two different research groups, the most significant association with BED. The remaining polymorphisms need further evidence to be confirmed.

HTR2A promotes the development of cardiac hypertrophy by activating PI3K-PDK1-AKT-mTOR signaling

5-Hydroxytryptamine receptor 2A (HTR2A) is a central regulator of fetal brain development and cognitive function in adults. However, the roles of HTR2A in the cardiovascular system are not fully understood. Here in this study, we explored the function of HTR2A in cardiac hypertrophy. Significantly, the expression levels of HTR2A mRNA and protein levels were upregulated in hypertrophic hearts of human patients. Besides, the expression of HTR2A was also upregulated in isoproterenol (ISO)-induced cardiac hypertrophy in the mouse. Next, the expression of HTR2A was knocked down with shRNA or overexpressed with adenovirus in neonatal rat cardiomyocytes, and ISO was used to induce cardiomyocyte hypertrophy. We showed that HTR2A knockdown repressed ISO-induced cardiomyocyte hypertrophy, which was demonstrated by decreased cardiomyocyte size and repressed expression of hypertrophic fetal genes (e.g., myosin heavy chain beta (β-Mhc), atrial natriuretic peptide (Anp), and brain natriuretic peptide (Bnp)). By contrast, HTR2A overexpression promoted cardiomyocyte hypertrophy. Of note, we observed that HTR2A promoted the activation (phosphorylation) of AKT-mTOR (mammalian target of rapamycin) signaling in cardiomyocytes, and repression of AKT-mTOR with perifosine or rapamycin blocked the effects of HTR2A on cardiomyocyte hypertrophy. Finally, we showed that HTR2A regulated AKT-mTOR signaling through activating the PI3K-PDK1 pathway, and inhibition of either PI3K or PDK1 blocked the roles of HTR2A in regulating AKT-mTOR signaling and cardiomyocyte hypertrophy. Altogether, these findings demonstrated that HTR2A activated PI3K-PDK1-AKT-mTOR signaling and promoted cardiac hypertrophy.

Genetic contributions to the etiology of anorexia nervosa: New perspectives in molecular diagnosis and treatment

Background

Anorexia nervosa is a multifactorial eating disorder that manifests with self‐starvation, extreme anxiety, hyperactivity, and amenorrhea. Long‐term effects include organ failure, disability, and in extreme cases, even death.

Methods

Through a literature search, here we summarize what is known about the molecular etiology of anorexia nervosa and propose genetic testing for this condition.

Results

Anorexia nervosa often has a familial background and shows strong heritability. Various genetic studies along with genome‐wide association studies have identified several genetic loci involved in molecular pathways that might lead to anorexia.

Conclusion

Anorexia nervosa is an eating disorder with a strong genetic component that contributes to its etiology. Various genetic approaches might help in the molecular diagnosis of this disease and in devising novel therapeutic options.

Anorexia nervosa is a multifactorial eating disorder with a strong genetic component that manifests with self‐starvation, extreme anxiety, hyperactivity, and amenorrhea. Through a literature search, here we summarize what is known about the molecular etiology of anorexia nervosa and propose genetic testing for this condition.

High polygenic burden is associated with blood DNA methylation changes in individuals with suicidal behavior

Suicidal behavior is result of the interaction of several contributors, including genetic and environmental factors. The integration of approaches considering the polygenic component of suicidal behavior, such as polygenic risk scores (PRS) and DNA methylation is promising for improving our understanding of the complex interplay between genetic and environmental factors in this behavior. The aim of this study was the evaluation of DNA methylation differences between individuals with high and low genetic burden for suicidality. The present study was divided into two phases. In the first phase, genotyping with the Psycharray chip was performed in a discovery sample of 568 Mexican individuals, of which 149 had suicidal behavior (64 individuals with suicidal ideation, 50 with suicide attempt and 35 with completed suicide). Then, a PRS analysis based on summary statistics from the Psychiatric Genomic Consortium was performed in the discovery sample. In a second phase, we evaluated DNA methylation differences between individuals with high and low genetic burden for suicidality in a sub-sample of the discovery sample (target sample) of 94 subjects. We identified 153 differentially methylated sites between individuals with low and high-PRS. Among genes mapped to differentially methylated sites, we found genes involved in neurodevelopment (CHD7, RFX4, KCNA1, PLCB1, PITX1, NUMBL) and ATP binding (KIF7, NUBP2, KIF6, ATP8B1, ATP11A, CLCN7, MYLK, MAP2K5). Our results suggest that genetic variants might increase the predisposition to epigenetic variations in genes involved in neurodevelopment. This study highlights the possible implication of polygenic burden in the alteration of epigenetic changes in suicidal behavior.

Genetic association analysis of 5-HTR2A gene variants in eating disorders in a Mexican population

INTRODUCTION

The 5-HTR2A gene has been implicated as candidate gene for eating disorders. The aim of the present study was to analyze the association of rs6311 and rs6313 polymorphisms of 5-HTR2A gene with eating disorders in Mexican population, and to evaluate if the polymorphisms of 5-HTR2A gene were associated with comorbidities in eating behavior.

METHODS

We conducted a case-control analysis with 460 subjects. We included 168 patients with eating disorders and 292 controls; two polymorphisms of 5-HTR2A gene were genotyped. We assessed the association by allele, genotype, and inheritance models. Psychiatric comorbidities were analyzed by genotype in patients with eating disorders.

RESULTS

We found an association between rs6311 and eating disorders in a Mexican population by allele (OR = 8.09; 95% CI = 5.99-11.03; p = 2.2e-16) and genotype (OR = 76.14; 95% CI = 35.61-177.18; p = 2.2e-16). Individuals who carried GG genotype showed increased risk for suicide attempted (OR = 2.14; CI = 1.10-4.26; p = 0.035) as comorbidity associated with eating disorders. No positive associations were observed for rs6313 polymorphism.

CONCLUSION

Our results showed an association of rs6311 (A1438G) polymorphism of 5-HTR2A gene with eating disorders, and these polymorphic variants could increase the risk of psychiatric comorbidities. However, more studies are required to replicate the results and to reach to a conclusive association between eating disorders and rs6311.