Association of the T102C polymorphism in the HTR2A gene with major depressive disorder, bipolar disorder, and schizophrenia

The Implication of 5-HT Receptor Family Members in Aggression, Depression and Suicide: Similarity and Difference

Being different multifactorial forms of psychopathology, aggression, depression and suicidal behavior, which is considered to be violent aggression directed against the self, have principal neurobiological links: preclinical and clinical evidence associates depression, aggression and suicidal behavior with dysregulation in central serotonergic (5-HT) neurotransmission. The implication of different types of 5-HT receptors in the genetic and epigenetic mechanisms of aggression, depression and suicidality has been well recognized. In this review, we consider and compare the orchestra of 5-HT receptors involved in these severe psychopathologies. Specifically, it concentrates on the role of 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2B, 5-HT_2C, 5-HT₃ and 5-HT₇ receptors in the mechanisms underlying the predisposition to aggression, depression and suicidal behavior. The review provides converging lines of evidence that: (1) depression-related 5-HT receptors include those receptors with pro-depressive properties (5-HT_2A, 5-HT₃ and 5-HT₇) as well as those providing an antidepressant effect (5-HT_1A, 5-HT_1B, 5-HT_2C subtypes). (2) Aggression-related 5-HT receptors are identical to depression-related 5-HT receptors with the exception of 5-HT₇ receptors. Activation of 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2C receptors attenuate aggressiveness, whereas agonists of 5-HT₃ intensify aggressive behavior.

Serotonin 5-HT2A receptor polymorphisms are associated with irritability and aggression in conduct disorder

In childhood and adolescence, overt antisocial and aggressive manifestations are typically diagnosed as conduct disorder (CD). Given that the emerging research has pointed to the influence of 5-HT_2A receptors in the ontogeny of aggression, we aimed to analyze the association of its genetic polymorphisms with CD. The study included 228 male adolescent subjects (120 with and 108 without CD). CD was diagnosed according to Structured Clinical Interview for DSM-IV criteria, while evaluations of aggressive/dissociative behaviors were performed using psychometric questionnaires including the PCL-YV, OAS-M, KADS, and CBCL. Platelet 5-HT concentration was determined by spectrophotofluorometry. Genotyping of 5-HT_2A receptor polymorphisms rs2070040, rs9534511, rs4142900, rs9534512 was performed using TaqMan SNP Genotyping Assays. Subjective irritability, physical aggression toward others, and antisocial behavior were strongly associated with the G allele of rs2070040 and rs4142900, and the C allele of rs9534511 and rs9534512. A significantly increased platelet 5-HT concentration in CD subjects, compared to controls, was lost after the correction according to the smoking status. Our results indicate an association of the studied HTR2A polymorphisms and their haplotypes with irritability and impulsivity traits, which may contribute to the aggressive and antisocial behavior in male adolescents with CD.

Brain 5-HT2A receptor binding and its neural network related to behavioral inhibition system

The tendency to avoid punishment, called behavioral inhibition system, is an essential aspect of motivational behavior. Behavioral inhibition system is related to negative affect, such as anxiety, depression and pain, but its neural basis has not yet been clarified. To clarify the association between individual variations in behavioral inhibition system and brain 5-HT2A receptor availability and specify which brain networks were involved in healthy male subjects, using [18F]altanserin positron emission tomography and resting-state functional magnetic resonance imaging. Behavioral inhibition system score negatively correlated with 5-HT2A receptor availability in anterior cingulate cortex. A statistical model indicated that the behavioral inhibition system score was associated with 5-HT2A receptor availability, which was mediated by the functional connectivity between anterior cingulate cortex and left middle frontal gyrus, both of which involved in the cognitive control of negative information processing. Individuals with high behavioral inhibition system displays low 5-HT2A receptor availability in anterior cingulate cortex and this cognitive control network links with prefrontal-cingulate integrity. These findings have implications for underlying the serotonergic basis of physiologies in aversion.

Association of Genetic Variants of Dopamine and Serotonin In Schizophrenia

BACKGROUND

Several studies indicated that antipsychotic treatment response and side effect manifestation can be different due to inter-individual variability in genetic variations.

AIM OF THE STUDY

Here we perform a case-control study to explore a potential association between schizophrenia and variants within the antipsychotic drug molecular targets (DRD1, DRD2, DRD3, HTR2A, HTR6) and metabolizing enzymes (CYP2D6, COMT) genes in Armenian population including also analysis of their possible relationship with disease clinical symptoms.

METHODS

A total of 18 SNPs was studied in patients with schizophrenia (n = 78) and healthy control subjects (n = 77) using MassARRAY genotyping.

RESULTS

We found that two studied genetic variants, namely DRD2 rs4436578*C and HTR2A rs6314*A are underrepresented in the group of patients compared to healthy subjects. After the correction for multiple testing, the rs4436578*C variant remained significant while the rs6314*A reported borderline significance. No significant differences in minor allele frequencies for other studied variants were identified. Also, a relationship between the genotypes and age of onset as well as disease duration has been detected.

CONCLUSIONS

The DRD2 rs4436578*C genetic variant might have protective role against schizophrenia, at least in Armenians.

An association study of dopaminergic (DRD2) and serotoninergic (5-HT2) gene polymorphism and schizophrenia in a North Indian population

The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in DRD2 and 5-HT2 receptor genes are associated with schizophrenia in North Indian population. Four hundred forty-three patients who met ICD10-DCR criteria for schizophrenia were enrolled from six participating centers along with 443 genetically related healthy subjects and 150 genetically unrelated healthy participants. A total of 7 gene polymorphisms from DRD2 (rs1800497, rs1079597, rs1800498, rs1801028) and 5-HT2 A (rs6313, rs6311, rs6305) were genotyped for their association with schizophrenia. No significant difference was found in frequency of various genotypes and alleles of the studied markers for DRD2 and 5-HT2 A genes between the cases and their genetic controls. However, significant differences were noted for rs1079597 genotype (Taq1B; p = 0.039) and its allele frequencies (p = 0.029) in persons with schizophrenia and the unrelated healthy controls. The DRD2 (Taq1 A-B-D) and 5-HT2 A (rs6311-rs6313-rs6305) haplotype frequencies differed significantly for A2B1D2 [p = 0.038; OR = 0.685 (95%CI = 0.479-0.981)] and ACC [p = 0.001; OR = 0.621 (95%CI = 0.461-0.838)] for the cases vs genetically related healthy controls. Similarly, significant difference was observed for the frequencies of GCC [p = 0.006; OR = 0.692 (95%CI = 0.532-0.900)] and ACC [p < 0.001; OR = 3.622 (95%CI = 1.73-7.585)] in the cases and unrelated healthy controls. Unlike previous research from India as well as abroad, the predominance of B1 allele of rs1079597 in patients with schizophrenia and absence of Cys311 in all study participants is a salient difference. Concluding, the B2 allele of rs1079597 may increase the risk of schizophrenia while the A2B1D2 haplotype may be protective in North Indian population.

The Interaction of TPH2 and 5-HT2A Polymorphisms on Major Depressive Disorder Susceptibility in a Chinese Han Population: A Case-Control Study

Purpose: TPH2 and 5-HT2A appear to play vital roles in the homeostatic regulation of serotonin levels in the brain, their genetic variations may lead to impaired homeostatic regulation of serotonin resulting in abnormal levels of serotonin in the brain, thus predisposing individuals to MDD. However, research studies have yet to confirm which gene-gene interaction effect between TPH2 and 5-HT2A polymorphisms results in increased susceptibility to MDD. Methods: A total of 565 participants, consisting of 278 MDD patients and 287 healthy controls from the Chinese Han population, were recruited for the present study. Six single nucleotide polymorphisms (SNPs) of TPH2/5-HT2A were selected to assess their interaction by use of a generalized multifactor dimensionality reduction method. Results: A-allele carriers of rs11178997 and rs120074175 were more likely to suffer from MDD than T-allele carriers of rs11178997, or G-allele carriers of rs120074175. The interaction between TPH2 (rs120074175, rs11178997) and 5-HT2A (rs7997012) was considered as the best multi-locus model upon the MDD susceptibility. Conclusions: Our data identified an important effect of TPH2 genetic variants (rs11178997 and rs120074175) upon the risk of MDD, and suggested that the interaction of TPH2/5-HT2A polymorphism variants confer a greater susceptibility to MDD in Chinese Han population.

Can lncRNAs be indicators for the diagnosis of early onset or acute schizophrenia and distinguish major depressive disorder and generalized anxiety disorder?-A cross validation analysis

Depression and anxiety are apparent symptoms in the early onset or acute phase of schizophrenia (SZ), which complicate timely diagnosis and treatment. It is imperative to seek an indicator to distinguish schizophrenia from depressive and anxiety disorders. Using lncRNA microarray profiling and RT-PCR, three up-regulated lncRNAs in SZ, six down-regulated lncRNAs in major depressive disorder (MDD), and three up-regulated lncRNAs in generalized anxiety disorder (GAD) had been identified as potential biomarkers. All the lncRNAs were, then, cross-validated in 40 SZ patients, 40 MDD patients, 40 GAD patients, and 40 normal controls. Compared with controls, three up-regulated SZ lncRNAs had a significantly down-regulated expression in GAD, and no remarkable differences existed between MDD and the controls. Additionally, the six down-regulated MDD lncRNAs were expressed in an opposite fashion in SZ, and the expression of the three up-regulated GAD lncRNAs were significantly different between SZ and GAD. These results indicate that the expression patterns of the three up-regulated SZ lncRNAs could not be completely replicated in MDD and GAD, and vice versa. Thus, these three SZ lncRNAs seem to be established as potential indicators for diagnosis of schizophrenia and distinguishing it from MDD and GAD. © 2017 Wiley Periodicals, Inc.

Meta-analysis of polymorphism rs6311 and rs6313 in the 5-HT2AR gene and schizophrenia

BACKGROUND

rs6311 and rs6313 polymorphism of 5-hydroxytryptamine 2A receptor has been widely studied regarding association with susceptibility to schizophrenia, but the results remained inconsistent.

AIMS

This study aimed to assess the association between rs6311 and rs6313 polymorphism and schizophrenia using a meta-analysis.

METHODS

Pubmed, Web of Science, and Embase databases were searched for all articles linking rs6311 and rs6313 polymorphism and schizophrenia. All studies which met the inclusion and exclusion criteria were included in this meta-analysis. Pooled odds ratio and 95% confidence intervals were used to evaluate the association between rs6311 and rs6313 polymorphism and schizophrenia risk. Sub-group analysis was also performed by different ethnic studies (Asian and Caucasian) and different minor allelic studies (rs6311: minor allele = A and minor allele = G; rs6313: minor allele = T and minor allele = C).

RESULTS

Forty articles, including 50 case-control studies, were included in this meta-analysis. Specifically, 12 studies with 4100 cases and 4541 controls involved rs6311, 38 studies with 8960 cases and 9729 controls involved rs6313. The results showed that rs6311 and rs6313 were not associated with schizophrenia. Moreover, no associations were found between rs6311 and schizophrenia in different sub-groups, rs6313 was found to associated with schizophrenia among studies in which C is the minor allele.

CONCLUSIONS

This meta-analysis indicates that rs6311 and rs6313 polymorphisms of 5-HT_2AR are not associated with schizophrenia. However, the rs6313 polymorphism is associated with schizophrenia in studies in which the minor allele is C.

Association study of 5-HT1A, 5-HT2A polymorphisms with schizophrenia and major depressive disorder in the Han Chinese population

Schizophrenia (SZ) and major depressive disorder (MDD) are two common severe mental disorders that have arisen to public awareness in recent years. Serotonin (5-HT) receptors have been implicated in the pathophysiology of psychiatric disorders especially in MDD and SZ. The aim of this study is to explore whether the variants in the 5-HT1A and 5-HT2A gene are susceptible to SZ or MDD in the Chinese Han population. Five SNPs (Single Nucleotide Polymorphisms) (rs1364043, rs10042486, rs6313, rs6311, rs17289304) in these genes were genotyped from 752 SZ patients, 568 MDD patients, and 846 normal controls of Chinese Han origin. The results showed that the 5-HT1A rs10042486 was significantly associated with SZ (Pallele=0.0369, Pgenotype=0.0098). Moreover, the haplotype (C-T) composed of rs10042486 and rs1364043 showed significant difference between SZ cases and healthy controls (P=0.0302) while another haplotype (T-G) was significant for MDD (P=0.0247). Our study is the first to suggest a positive association of the 5-HT1A gene with SZ in the Han Chinese population.

Disorder-specific genetic factors in obsessive-compulsive disorder: A comprehensive meta-analysis

Much remains to be learned about the etiology of obsessive-compulsive disorder (OCD). Twin studies suggest that it arises from both disorder-specific and non-specific genetic factors. To understand the etiology of OCD per se, it is necessary to identify disorder-specific factors. Previous research shows that OCD is associated with serotonin-related polymorphisms (5-HTTLPR coded as triallelic and HTR2A rs6311/rs6313) and, in males, a polymorphism involved in catecholamine modulation; COMT (rs4680). The present study is the first comprehensive meta-analysis to investigate whether these polymorphisms are specific to OCD. A meta-analysis was conducted for genetic association studies of OCD or any other psychiatric disorder, published in any language, in any country. A total of 551 studies were examined, of which 290 were included, consisting of 47,358 cases and 68,942 controls from case control studies, and 2,443 trios from family based studies. The main meta-analysis was limited to those disorders in which there were at least five datasets (studies or sub-studies) per disorder. Results confirmed that OCD is associated with polymorphisms of 5-HTTLPR, HTR2A, and, in males only, COMT. These polymorphisms were not associated with almost all other forms of psychopathology, including unipolar mood disorders, bipolar disorder, panic disorder, schizophrenia, and alcohol dependence. OCD, compared to most other disorders, had a significantly stronger association with particular alleles of each of the polymorphisms. Results did not differ across ancestral groups (Asian vs. Caucasian), designs (case control vs. family based), or diagnostic systems. Results suggest that the polymorphisms investigated in this study are relatively specific to OCD.

SK3 Channel Overexpression in Mice Causes Hippocampal Shrinkage Associated with Cognitive Impairments

The dysfunction of the small-conductance calcium-activated K⁺ channel SK3 has been described as one of the factors responsible for the progress of psychoneurological diseases, but the molecular basis of this is largely unknown. This report reveals through use of immunohistochemistry and computational tomography that long-term increased expression of the SK3 small-conductance calcium-activated potassium channel (SK3-T/T) in mice induces a notable bilateral reduction of the hippocampal area (more than 50 %). Histological analysis showed that SK3-T/T mice have cellular disarrangements and neuron discontinuities in the hippocampal formation CA1 and CA3 neuronal layer. SK3 overexpression resulted in cognitive loss as determined by the object recognition test. Electrophysiological examination of hippocampal slices revealed that SK3 channel overexpression induced deficiency of long-term potentiation in hippocampal microcircuits. In association with these results, there were changes at the mRNA levels of some genes involved in Alzheimer’s disease and/or linked to schizophrenia, epilepsy, and autism. Taken together, these features suggest that augmenting the function of SK3 ion channel in mice may present a unique opportunity to investigate the neural basis of central nervous system dysfunctions associated with schizophrenia, Alzheimer’s disease, or other neuropsychiatric/neurodegenerative disorders in this model system. As a more detailed understanding of the role of the SK3 channel in brain disorders is limited by the lack of specific SK3 antagonists and agonists, the results observed in this study are of significant interest; they suggest a new approach for the development of neuroprotective strategies in neuropsychiatric/neurodegenerative diseases with SK3 representing a potential drug target.

The C825T Polymorphism of the G-Protein β3 Gene as a Risk Factor for Depression: A Meta-Analysis

Background

TheG-protein β3 gene (GNβ3) has been implicated in psychiatric illness through its effects upon intracellular transduction of several neurotransmitter receptors. Multiple studies have investigated the relationship of the C825T polymorphism of the GNβ3 gene (GNβ3 C825T) to depression and antidepressant response. However, the relationship between GNβ3 C825T and depression remains inconsistent. Therefore, here we performed a meta-analysis to investigate the role of GNβ3 C825Tin depression risk.

Methods

Published case-control studies examining the association between GNβ3 C825T and depression were systematically searched for through several electronic databases (PubMed, Scopus, Science Direct, Springer, Embase, psyINFO, and CNKI). The association between GNβ3 C825T and depression risk were assessed by odd ratios (ORs) and their 95% confidence intervals (CIs) for each study. Pooled ORs were constructed for allele contrast (C versus T), homozygote (CC versus TT) model, heterozygote (CC versus CT) model, dominant model (CC + CT versus TT), and recessive (CC versus TT+CT) model. In order to evaluate possible biases, a sensitivity analysis was conducted by sequential deletion of individual studies in an attempt to assess the contribution of each individual dataset to the pooled OR.

Results

Nine studies, including 1055 depressed patients and 1325 healthy controls, were included. A significant association between GNβ3 C825Tand depression was found to exist, suggesting that the T-allele of GNβ3 C825Tcan increase susceptibility to depression. After stratification by ethnicity, the same association was found in the Asian subpopulation, but not the Caucasian subpopulation.

Conclusions

This is the first meta-analysis to reveal a relationship between GNβ3 C825T and depression. Asian T-allele carriers of GNβ3 C825T appear to be more susceptible to depression.