Glutamate receptor, metabotropic 7 (GRM7) gene variations and susceptibility to autism: A case-control study

Impact of GRM7 gene variations on glioblastoma risk in the Iranian population

AIM

The metabotropic glutamate receptor, GRM7 is a gene in the neurotransmitters prognostic signatures. Downregulation of this gene is associated with the progression of glioma tumors and has a negative impact on the immune response.

METHODS

In the present study, we aim to assess the associations between rs6782011 and rs779867 SNPs within this gene and risk of glioblastoma multiforme (GBM) in Iranian population.

RESULTS

There was a noteworthy difference in distribution of genotypes (P value = 0.001) and alleles (P value = 0.0002) of rs779867 between total GBM cases (n = 299) and total normal controls (n = 302). In addition, the significant difference in genotypes and alleles distribution was observed for both male and female GBM cases vs. respective normal controls. For rs6782011 variant, the significant difference in genotypes distribution was observed between male GBM cases (n = 187) vs. respective normal controls (n = 156) (P value = 0.004) and between total GBM cases (n = 299) vs. total normal controls (n = 302) (P value = 0.02). However, there was no significant difference in genotypes distribution between female GBM cases and respective normal controls (P value = 0.1). Distribution of rs6782011 alleles was not different between total GBM cases and normal controls; and between male GBM cases and male normal controls. However, there was a significant difference in alleles distribution between female GBM cases and female normal controls.

CONCLUSION

Taken together, the mentioned polymorphisms might affect risk of GBM in Iranian population. Future studies are needed to elaborate the underlying mechanism.

Decoding the genetic landscape of autism: A comprehensive review

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by heterogeneous symptoms and genetic underpinnings. Recent advancements in genetic and epigenetic research have provided insights into the intricate mechanisms contributing to ASD, influencing both diagnosis and therapeutic strategies.

AIM

To explore the genetic architecture of ASD, elucidate mechanistic insights into genetic mutations, and examine gene-environment interactions.

METHODS

A comprehensive systematic review was conducted, integrating findings from studies on genetic variations, epigenetic mechanisms (such as DNA methylation and histone modifications), and emerging technologies [including Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 and single-cell RNA sequencing]. Relevant articles were identified through systematic searches of databases such as PubMed and Google Scholar.

RESULTS

Genetic studies have identified numerous risk genes and mutations associated with ASD, yet many cases remain unexplained by known factors, suggesting undiscovered genetic components. Mechanistic insights into how these genetic mutations impact neural development and brain connectivity are still evolving. Epigenetic modifications, particularly DNA methylation and non-coding RNAs, also play significant roles in ASD pathogenesis. Emerging technologies like CRISPR-Cas9 and advanced bioinformatics are advancing our understanding by enabling precise genetic editing and analysis of complex genomic data.

CONCLUSION

Continued research into the genetic and epigenetic underpinnings of ASD is crucial for developing personalized and effective treatments. Collaborative efforts integrating multidisciplinary expertise and international collaborations are essential to address the complexity of ASD and translate genetic discoveries into clinical practice. Addressing unresolved questions and ethical considerations surrounding genetic research will pave the way for improved diagnostic tools and targeted therapies, ultimately enhancing outcomes for individuals affected by ASD.

GRM7 deficiency, from excitotoxicity and neuroinflammation to neurodegeneration: Systematic review of GRM7 deficient patients

The metabotropic glutamate receptor 7 (mGluR7) is a presynaptic G-protein-coupled glutamate receptor that modulates neurotransmitter release and synaptic plasticity at presynaptic terminals. It is encoded by GRM7, and recently variants have been identified in patients with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), developmental delay (DD), intellectual disability (ID), and brain malformations. To gain updated insights into the function of GRM7 and the phenotypic spectrum of genetic variations within this gene, we conducted a systematic review of relevant literature utilizing PubMed, Web of Science, and Scopus databases. Among the 14 articles meeting the inclusion criteria, a total of 42 patients (from 28 families) harboring confirmed mutations in the GRM7 gene have been documented. Specifically, there were 17 patients with heterozygous mutations, 20 patients with homozygous mutations, and 5 patients with compound heterozygous mutations. Common clinical features included intellectual behavioral disability, seizure/epilepsy, microcephaly, developmental delay, peripheral hypertonia and hypomyelination. Genotype-phenotype correlation was not clear and each variant had unique characteristics including gene dosage, mutant protein surface expression, and degradation pathway that result with a spectrum of phenotype manifestations through ASD or ADHD to severe DD/ID with brain malformations. Neuroinflammation may play a role in the development and/or progression of GRM7-related neurodegeneration along with excitotoxicity. The clinical and functional data presented here demonstrate that both autosomal dominant and recessive inheritance of GRM7 mutation can cause disease spectrum phenotypes through ASD or ADHD to severe DD/ID and seizure with brain malformations.

Comprehensive systematic review and meta-analysis of the association between common genetic variants and autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is neurodevelopmental disorder characterized by stereotyped behavior and deficits in communication and social interactions. To date, numerous studies have investigated the associations between genetic variants and ASD risk. However, the results of these published studies lack a clear consensus. In the present study, we performed a systematic review on the association between genetic variants and ASD risk. Meanwhile, we conducted a meta-analysis on available data to identify the association between the single nucleotide polymorphisms (SNPs) of candidate genes and ASD risk.

METHODS

We systematically searched public databases including English and Chinese from their inception to August 1, 2022. Two independent reviewers extracted data and assessed study quality. Odds ratio and 95 % confidence interval were used as effect indexes to evaluate the association between the SNPs of candidate genes and the risk of ASD. Heterogeneity was explored through subgroup, sensitivity, and meta-regression analyses. Publication bias was assessed by using Egger's and Begg's tests for funnel plot asymmetry. In addition, TSA analysis were performed to confirm the study findings.

RESULTS

We summarized 84 SNPs of 32 candidate genes from 81 articles included in the study. Subsequently, we analyzed 16 SNPs of eight genes by calculating pooled ORs, and identified eight significant SNPs of contactin associated protein 2 (CNTNAP2), methylentetrahydrofolate reductase (MTHFR), oxytocin receptor (OXTR), and vitamin D receptor (VDR). Results showed that seven SNPs, including the CNTNAP2 rs2710102 (homozygote, heterozygote, dominant and allelic models) and rs7794745 (heterozygote and dominant models), MTHFR C677T (homozygote, heterozygote, dominant, recessive and allelic models) and A1298C (dominant and allelic models), OXTR rs2254298 (homozygote and recessive models), VDR rs731236 (homozygote, dominant, recessive and allelic models) and rs2228570 (homozygote and recessive models), were showed to be correlated with an increased ASD risk. By contrast, the VDR rs7975232 was correlated with a decreased the risk of ASD under the homozygote and allelic models.

CONCLUSION

Our study summarized research evidence on the genetic variants of ASD and provides a broad and detailed overview of ASD risk genes. The C677T and A1298C polymorphisms of MTHFR, rs2710102 and rs7794745 polymorphisms of CNTNAP2, rs2254298 polymorphism of OXTR, and rs731236 and rs2228570 polymorphisms of VDR were genetic risk factors. The rs7975232 polymorphism of VDR was a genetic protective factor for ASD. Our study provides novel clues to clinicians and healthcare decision-makers to predict ASD susceptibility.

Associations between GRM7 polymorphisms and obesity in patients selected for sleeve gastrectomy

Obesity is a worldwide problem in which genetic factors have a prominent role. We have selected two single nucleotide polymorphisms (SNPs) within glutamate metabotropic receptor 7 (GRM7) gene, namely rs6782011 and rs779867 to weigh their association with obesity in an Iranian cohort. The distribution of rs6782011 alleles was significantly different in the obese patients from normal controls (P < 0.0001; 434 obese patients vs. 297 normal controls). Distribution of alleles was also measured between sex-based groups of obese patients and controls. We detected remarkable differences between female obese cases and female control subjects (P < 0.0001; 374 female obese cases vs. 216 female normal controls); nevertheless, the difference in allele distribution was not significant for male cases compared with corresponding normal controls (p = 0.47; 60 male patients vs. 81 normal males). Contrariwise, distribution of rs779867 alleles was not significantly different between total obese patients compared with normal controls (P = 0.21; 434 obese patients vs. 297 normal BMI controls). There was also no significant difference for female and male obese patients compared with female and male normal BMI controls. Thus, GRM7 can be considered as a risk locus for obesity.

A pilot study on glutamate receptor and carrier gene variants and risk of childhood autism spectrum

Imbalanced glutamate signaling has been implicated in the development of autism spectrum disorder (ASD). This case-control study was to examine single nucleotide polymorphisms (SNPs) in glutamate receptor and carrier genes and determine their association with childhood ASD in a Chinese Han population. A total of 12 SNPs in genes encoding glutamate receptors (GRM7 and GRM8) and carriers (SLC1A1 and SLC25A12) were examined in 249 autistic children and 353 healthy controls. The Childhood Autism Rating Scale (CARS) and its verbal communication domain were applied to evaluate the severity of the disease and language impairment, respectively. The T allele of rs2292813 in the SLC25A12 gene was significantly associated with an increased risk of ASD (odds ratio (OD) = 1.7, 95% confidence interval (CI): 1.1-2.6, P = 0.0107). Neither the genotypes nor allele distributions of other SNPs were associated with the risk of ASD. Notably, rs1800656 and rs2237731 in the GRM8 gene, but not other SNPs, were related to the severity of language impairment. All SNPs were not correlated with the overall severity of ASD. Our findings support associations between the SLC25A12 gene variant and the risk of childhood ASD, and between the GRM8 gene variant and the severity of language impairment in the Chinese Han population.

Modelling Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) Using Mice and Zebrafish

Autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) are two debilitating neurodevelopmental disorders. The former is associated with social impairments whereas the latter is associated with inattentiveness, hyperactivity, and impulsivity. There is recent evidence that both disorders are somehow related and that genes may play a large role in these disorders. Despite mounting human and animal research, the neurological pathways underlying ASD and ADHD are still not well understood. Scientists investigate neurodevelopmental disorders by using animal models that have high similarities in genetics and behaviours with humans. Mice have been utilized in neuroscience research as an excellent animal model for a long time; however, the zebrafish has attracted much attention recently, with an increasingly large number of studies using this model. In this review, we first discuss ASD and ADHD aetiology from a general point of view to their characteristics and treatments. We also compare mice and zebrafish for their similarities and discuss their advantages and limitations in neuroscience. Finally, we summarize the most recent and existing research on zebrafish and mouse models of ASD and ADHD. We believe that this review will serve as a unique document providing interesting information to date about these models, thus facilitating research on ASD and ADHD.

Multiple Recurrent Copy Number Variations (CNVs) in Chromosome 22 Including 22q11.2 Associated with Autism Spectrum Disorder

Introduction

Autism spectrum disorder (ASD) is a developmental disorder that can cause substantial social, communication, and behavioral challenges. Genetic factors play a significant role in ASD, where the risk of ASD has been increased for unclear reasons. Twin studies have shown important evidence of both genetic and environmental contributions in ASD, where the level of contribution of these factors has not been proven yet. It has been suggested that copy number variation (CNV) duplication and the deletion of many genes in chromosome 22 (Ch22) may have a strong association with ASD. This study screened the CNVs in Ch22 in autistic Saudi children and assessed the candidate gene in the CNVs region of Ch22 that is most associated with ASD.

Methods

This study included 15 autistic Saudi children as well as 4 healthy children as controls; DNA was extracted from samples and analyzed using array comparative genomic hybridization (aCGH) and DNA sequencing.

Results

The aCGH detected (in only 6 autistic samples) deletion and duplication in many regions of Ch22, including some critical genes. Moreover, DNA sequencing determined a genetic mutation in the TBX1 gene sequence in autistic samples. This study, carried out using aCGH, found that six autistic patients had CNVs in Ch22, and DNA sequencing revealed mutations in the TBX1 gene in autistic samples but none in the control.

Conclusion

CNV deletion and the duplication of the TBX1 gene could be related to ASD; therefore, this gene needs more analysis in terms of expression levels.

Autism Spectrum Disorder: Focus on Glutamatergic Neurotransmission

Disturbances in the glutamatergic system have been increasingly documented in several neuropsychiatric disorders, including autism spectrum disorder (ASD). Glutamate-centered theories of ASD are based on evidence from patient samples and postmortem studies, as well as from studies documenting abnormalities in glutamatergic gene expression and metabolic pathways, including changes in the gut microbiota glutamate metabolism in patients with ASD. In addition, preclinical studies on animal models have demonstrated glutamatergic neurotransmission deficits and altered expression of glutamate synaptic proteins. At present, there are no approved glutamatergic drugs for ASD, but several ongoing clinical trials are currently focusing on evaluating in autistic patients glutamatergic pharmaceuticals already approved for other conditions. In this review, we provide an overview of the literature concerning the role of glutamatergic neurotransmission in the pathophysiology of ASD and as a potential target for novel treatments.

A systematic review of common genetic variation and biological pathways in autism spectrum disorder

Background

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by persistent deficits in social communication and interaction. Common genetic variation appears to play a key role in the development of this condition. In this systematic review, we describe the relationship between genetic variations and autism. We created a gene dataset of the genes involved in the pathogenesis of autism and performed an over-representation analysis to evaluate the biological functions and molecular pathways that may explain the associations between these variants and the development of ASD.

Results

177 studies and a gene set composed of 139 were included in this qualitative systematic review. Enriched pathways in the over-representation analysis using the KEGG pathway database were mostly associated with neurotransmitter receptors and their subunits. Major over-represented biological processes were social behavior, vocalization behavior, learning and memory. The enriched cellular component of the proteins encoded by the genes identified in this systematic review were the postsynaptic membrane and the cell junction.

Conclusions

Among the biological processes that were examined, genes involved in synaptic integrity, neurotransmitter metabolism, and cell adhesion molecules were significantly involved in the development of autism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-021-00662-z.

Changes in the Number and Morphology of Dendritic Spines in the Hippocampus and Prefrontal Cortex of the C58/J Mouse Model of Autism

Autism spectrum disorder (ASD) has a broad range of neurobiological characteristics, including alterations in dendritic spines, where approximately 90% of excitatory synapses occur. Therefore, changes in their number or morphology would be related to atypical brain communication. The C58/J inbred mouse strain displays low sociability, impaired communication, and stereotyped behavior; hence, it is considered among the animal models suitable for the study of idiopathic autism. Thus, this study aimed to evaluate the dendritic spine differences in the hippocampus and the prefrontal cortex of C58/J mice. We found changes in the number of spines and morphology in a brain region-dependent manner: a subtle decrease in spine density in the prefrontal cortex, higher frequency of immature phenotype spines characterized by filopodia-like length or small morphology, and a lower number of mature phenotype spines with mushroom-like or wide heads in the hippocampus. Moreover, an in silico analysis showed single nucleotide polymorphisms (SNPs) at genes collectively involved in regulating structural plasticity with a likely association with ASD, including MAP1A (Microtubule-Associated Protein 1A), GRM7 (Metabotropic Glutamate Receptor, 7), ANKRD11 (Ankyrin Repeat Domain 11), and SLC6A4 (Solute Carrier Family 6, member 4), which might support the relationship between the C58/J strain genome, an autistic-like behavior, and the observed anomalies in the dendritic spines.

Genetic and molecular biology of autism spectrum disorder among Middle East population: a review

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disease, characterized by impaired social communication, executive dysfunction, and abnormal perceptual processing. It is more frequent among males. All of these clinical manifestations are associated with atypical neural development. Various genetic and environmental risk factors are involved in the etiology of autism. Genetic assessment is essential for the early detection and intervention which can improve social communications and reduce abnormal behaviors. Although, there is a noticeable ASD incidence in Middle East countries, there is still a lack of knowledge about the genetic and molecular biology of ASD among this population to introduce efficient diagnostic and prognostic methods.

MAIN BODY

In the present review, we have summarized all of the genes which have been associated with ASD progression among Middle East population. We have also categorized the reported genes based on their cell and molecular functions.

CONCLUSIONS

This review clarifies the genetic and molecular biology of ASD among Middle East population and paves the way of introducing an efficient population based panel of genetic markers for the early detection and management of ASD in Middle East countries.

Pathogenic GRM7 Mutations Associated with Neurodevelopmental Disorders Impair Axon Outgrowth and Presynaptic Terminal Development

Metabotropic glutamate receptor 7 (mGlu7) is an inhibitory heterotrimeric G-protein-coupled receptor that modulates neurotransmitter release and synaptic plasticity at presynaptic terminals in the mammalian central nervous system. Recent studies have shown that rare mutations in glutamate receptors and synaptic scaffold proteins are associated with neurodevelopmental disorders (NDDs). However, the role of presynaptic mGlu7 in the pathogenesis of NDDs remains largely unknown. Recent whole-exome sequencing (WES) studies in families with NDDs have revealed that several missense mutations (c.1865G>A:p.R622Q; c.461T>C:p.I154T; c.1972C>T:p.R658W and c.2024C>A:p.T675K) or a nonsense mutation (c.1757G>A:p.W586X) in the GRM7 gene may be linked to NDDs. In the present study, we investigated the mechanistic links between GRM7 point mutations and NDD pathology. We find that the pathogenic GRM7 I154T and R658W/T675K mutations lead to the degradation of the mGlu7 protein. In particular, the GRM7 R658W/T675K mutation results in a lack of surface mGlu7 expression in heterologous cells and cultured neurons isolated from male and female rat embryos. We demonstrate that the expression of mGlu7 variants or exposure to mGlu7 antagonists impairs axon outgrowth through the mitogen-activated protein kinase (MAPK)-cAMP-protein kinase A (PKA) signaling pathway during early neuronal development, which subsequently leads to a decrease in the number of presynaptic terminals in mature neurons. Treatment with an mGlu7 agonist restores the pathologic phenotypes caused by mGlu7 I154T but not by mGlu7 R658W/T675K because of its lack of neuronal surface expression. These findings provide evidence that stable neuronal surface expression of mGlu7 is essential for neural development and that mGlu7 is a promising therapeutic target for NDDs.SIGNIFICANCE STATEMENT Neurodevelopmental disorders (NDDs) affect brain development and function by multiple etiologies. Metabotropic glutamate receptor 7 (mGlu7) is a receptor that controls excitatory neurotransmission and synaptic plasticity. Since accumulating evidence indicates that the GRM7 gene locus is associated with NDD risk, we analyzed the functional effects of human GRM7 variants identified in patients with NDDs. We demonstrate that stable neuronal surface expression of mGlu7 is essential for axon outgrowth and presynaptic terminal development in neurons. We found that mitogen-activated protein kinase (MAPK)-cAMP-protein kinase A (PKA) signaling and subsequent cytoskeletal dynamics are defective because of the degradation of mGlu7 variants. Finally, we show that the defects caused by mGlu7 I154T can be reversed by agonists, providing the rationale for proposing mGlu7 as a potential therapeutic target for NDDs.

Association between the group III metabotropic glutamate receptor gene polymorphisms and attention-deficit/hyperactivity disorder and functional exploration of risk loci

Existing evidence suggests that the group III metabotropic glutamate receptor (mGluR) gene variations are involved in attention-deficit/hyperactivity disorder (ADHD), but few studies have fully explored this association. We conducted a case-control study with 617 cases and 636 controls to investigate the association between functional single-nucleotide polymorphisms (SNPs) from the group III mGluR gene polymorphisms (GRM4, GRM7, GRM8) and ADHD in the Chinese Han population and initially explored the function of positive SNPs. The GRM4 rs1906953 T genotype showed a significant association with a decreased risk of ADHD (TT:CC, OR = 0.55, 95% CI = 0.40-0.77; recessive model, OR = 0.58, 95% CI = 0.43-0.78). GRM7 rs9826579 C showed a significant association with an increased risk of ADHD (TC:TT, OR = 1.81, 95% CI = 1.39-2.36; dominant model, OR = 1.74, 95% CI = 1.35-2.24; additive model, OR = 1.56, 95% CI = 1.24-1.97). In addition, compared with subjects with the rs1906953 TT genotype, subjects with of the CC genotype showed more obvious attention deficit behaviours and hyperactivity/impulsive behaviours. Dual-luciferase reporter gene assays showed that a promoter reporter with the rs1906953 TT genotype significantly decreased luciferase activity compared with the CC genotype. According to electrophoretic mobility shift assays, the binding capacity of rs1906953 T probe with nucleoprotein was lower than that of the rs1906953 C probe. Our results revealed the association of GRM4 rs1906953 and GRM7 rs9826579 with ADHD. Moreover, we found that rs1906953 disturbs the transcriptional activity of GRM4.

Comprehensive Profiling of Gene Expression in the Cerebral Cortex and Striatum of BTBRTF/ArtRbrc Mice Compared to C57BL/6J Mice

Mouse line BTBR T+ Iptr3^tf/J (hereafter referred as to BTBR/J) is a mouse strain that shows lower sociability compared to the C57BL/6J mouse strain (B6) and thus is often utilized as a model for autism spectrum disorder (ASD). In this study, we utilized another subline, BTBRTF/ArtRbrc (hereafter referred as to BTBR/R), and analyzed the associated brain transcriptome compared to B6 mice using microarray analysis, quantitative RT-PCR analysis, various bioinformatics analyses, and in situ hybridization. We focused on the cerebral cortex and the striatum, both of which are thought to be brain circuits associated with ASD symptoms. The transcriptome profiling identified 1,280 differentially expressed genes (DEGs; 974 downregulated and 306 upregulated genes, including 498 non-coding RNAs [ncRNAs]) in BTBR/R mice compared to B6 mice. Among these DEGs, 53 genes were consistent with ASD-related genes already established. Gene Ontology (GO) enrichment analysis highlighted 78 annotations (GO terms) including DNA/chromatin regulation, transcriptional/translational regulation, intercellular signaling, metabolism, immune signaling, and neurotransmitter/synaptic transmission-related terms. RNA interaction analysis revealed novel RNA–RNA networks, including 227 ASD-related genes. Weighted correlation network analysis highlighted 10 enriched modules including DNA/chromatin regulation, neurotransmitter/synaptic transmission, and transcriptional/translational regulation. Finally, the behavioral analyses showed that, compared to B6 mice, BTBR/R mice have mild but significant deficits in social novelty recognition and repetitive behavior. In addition, the BTBR/R data were comprehensively compared with those reported in the previous studies of human subjects with ASD as well as ASD animal models, including BTBR/J mice. Our results allow us to propose potentially important genes, ncRNAs, and RNA interactions. Analysis of the altered brain transcriptome data of the BTBR/R and BTBR/J sublines can contribute to the understanding of the genetic underpinnings of autism susceptibility.

[Pathophysiological mechanisms of autism in children]

Based on the analysis of literature, the authors describe the neuropathophysiological mechanism of the formation of synapses, synaptic transmission and plasticity, which may underlie the pathogenesis of autism. The results of some studies confirm the involvement of aberrant expression of genes and proteins of synaptic contacts, cell adhesion molecules p120ctn, CNTN5, CNTN6, activation of NMDA glutamate, TrkB, p75 receptors, Ca²⁺-input, BDNF, serotonin and testosterone. This leads to an imbalance in the exciting, inhibitory synaptic transmission and forms of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD) at the level of individual neurons and their chains due to suppression of GABA synthesis, expression of its ionotropic and metabotropic receptors, G proteins, NGF, TrkA receptors, a reduction in the number of GABAergic neurons, their contacts and disruption of differentiation. The pathology of the nuclei of the thalamus, especially the reticular nucleus (RN), is associated with a disturbance of the expression of the subunits of metabotropic GABAβ receptors, Ca²⁺ channels, GABA excretion and the work of chlorine transmitters. These failures do not ensure the inhibitory effect of OC on the exciting associative and ventral nuclei of the thalamus, nor modify the incoming information to the cerebral cortex (CC) from these thalamus nuclei, the dentate gyrus of the hippocampus and the nuclei of the reticular formation. Information propagating into the somatosensory and associative regions of CC is not modified by mirror neurons (MN) when performing arbitrary actions, which prevents the formation of an adequate image in the neural networks of the associative cortex and promotes the development of hyperexcitability, irritability, increased visual and auditory sensitivity, anxiety, and the ability to form a holistic image based on the actions of other people.

A telescope GWAS analysis strategy, based on SNPs-genes-pathways ensamble and on multivariate algorithms, to characterize late onset Alzheimer's disease

Genome–wide association studies (GWAS) have revealed a plethora of putative susceptibility genes for Alzheimer’s disease (AD), with the sole exception of APOE gene unequivocally validated in independent study. Considering that the etiology of complex diseases like AD could depend on functional multiple genes interaction network, here we proposed an alternative GWAS analysis strategy based on (i) multivariate methods and on a (ii) telescope approach, in order to guarantee the identification of correlated variables, and reveal their connections at three biological connected levels. Specifically as multivariate methods, we employed two machine learning algorithms and a genetic association test and we considered SNPs, Genes and Pathways features in the analysis of two public GWAS dataset (ADNI-1 and ADNI-2). For each dataset and for each feature we addressed two binary classifications tasks: cases vs. controls and the low vs. high risk of developing AD considering the allelic status of APOEe4. This complex strategy allowed the identification of SNPs, genes and pathways lists statistically robust and meaningful from the biological viewpoint. Among the results, we confirm the involvement of TOMM40 gene in AD and we propose GRM7 as a novel gene significantly associated with AD.

Molecular Biomarkers Predictive of Sertraline Treatment Response in Young Children With Autism Spectrum Disorder

Sertraline is one among several selective serotonin reuptake inhibitors (SSRIs) that exhibited improvement of language development in Autism Spectrum Disorder (ASD); however, the molecular mechanism has not been elucidated. A double blind, randomized, 6-month, placebo-controlled, clinical trial of low-dose sertraline in children ages (3-6 years) with ASD was conducted at the UC Davis MIND Institute. It aimed at evaluating the efficacy and benefit with respect to early expressive language development and global clinical improvement. This study aimed to identify molecular biomarkers that might be key players in the serotonin pathway and might be predictive of a clinical response to sertraline. Fifty eight subjects with the diagnosis of ASD were randomized to sertraline or placebo. Eight subjects from the sertraline arm and five from the placebo arm discontinued from the study. Furthermore, four subjects did not have a successful blood draw. Hence, genotypes for 41 subjects (20 on placebo and 21 on sertraline) were determined for several genes involved in the serotonin pathway including the serotonin transporter-linked polymorphic region (5-HTTLPR), the tryptophan hydroxylase 2 (TPH2), and the Brain-Derived Neurotrophic Factor (BDNF). In addition, plasma levels of BDNF, Matrix metallopeptidase 9 (MMP-9) and a selected panel of cytokines were determined at baseline and post-treatment. Intent-to-treat analysis revealed several primary significant correlations between molecular changes and the Mullen Scales of Early Learning (MSEL) and Clinical Global Impression Scale - Improvement (CGI-I) of treatment and control groups but they were not significant after adjustment for multiple testing. Thus, sertraline showed no benefit for treatment of young children with ASD in language development or changes in molecular markers in this study. These results indicate that sertraline may not be beneficial for the treatment of children with ASD; however, further investigation of larger groups as well as longer term follow-up studies are warranted.

GRM7 polymorphisms are not associated with ischemic stroke in Iranian population

Objectives: Ischemic stroke is the main neurological cause of acquired incapability in adults and a prominent cause of mortality. Several association studies have been conducted to explore the role of candidate genes in this neurological condition.Methods: In the present study, we aimed at identification of association between Glutamate Metabotropic Receptor 7 (GRM7) and risk of ischemic stroke in Iranian population. Two intronic variants within this gene (rs6782011 and rs779867) were genotyped in 318 sporadic ischemic stroke cases and 300 unrelated, healthy controls individuals.Results: No significant difference was found in allele, genotype or haplotype frequencies of these SNPs between cases and controls after correction for multiple comparisons.Conclusion: Consequently, the assessed GRM7 variants are not implicated in risk of ischemic stroke in Iranian population.

IFNG/IFNG-AS1 expression level balance: implications for autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder associated with different epidemiological, genetic, epigenetic, and environmental factors. Although its etiology is not fully understood, immune dysfunction is implicated in this disease. Recently, a large number of genes encoding long noncoding RNAs (lncRNAs) were discovered which act as positive or negative regulators of neighboring target genes. The lncRNA, Interferon gamma-antisense RNA (IFNG-AS1), regulates expression levels of the Interferon gamma (IFNG) gene. In the present study, we investigated expression of IFNG and IFNG-AS1 in 50 children with ASD (15 females and 35 males, mean age: 6 ± 1.4 years) and 50 healthy controls (14 females and 36 males, mean age: 6 ± 1.74 years) by real time PCR technique. The results showed significant up-regulation of IFNG and down-regulation of IFNG-AS1 expression in children with ASD compared to controls (Fold change = 1.5, P < 0.0001; Fold change = -0.143, P = 0.013, respectively). The IFNG expression level increase was more pronounced in male ASD children (Fold change = 1.621; p < 0.0001). Our data reveal a functional disruption in the interactive network of IFNG/IFNG-AS1 regulation, which could be a contributing factor in the chronic inflammatory aspect of ASD. Our findings can help understanding the underlying contributors to ASD pathogenesis and find novel treatment options for children with ASD.

GRM7 polymorphisms and risk of schizophrenia in Iranian population

The role of metabotropic glutamate receptors in the pathogenesis of schizophrenia or response to antipsychotic treatment has been proposed previously. The aim of the current study was to investigate the associations between two intronic variants within GRM7 gene (rs6782011 and rs779867) and schizophrenia in Iranian population. These two single nucleotide polymorphisms (SNPs) were genotyped in 273 schizophrenic patients and 300 age and sex-matched normal controls. The frequency of A allele of the rs779867 was significantly lower in the schizophrenic patients compared with healthy subjects (OR (95% CI) = 0.71 (0.56-0.89), adjusted P value = 0.008). This SNP was associated with schizophrenia in co-dominant and dominant models (adjusted P values of 0.03 and 0.02 respectively). However, there was no difference in allele and genotype frequencies of the rs6782011 SNP between cases and controls. Consequently, the results of current study further highlight the participation of GRM7 in the pathogenesis of schizophrenia.

Application of Single-Nucleotide Polymorphisms in the Diagnosis of Autism Spectrum Disorders: A Preliminary Study with Artificial Neural Networks

Autism spectrum disorder (ASD) includes different neurodevelopmental disorders characterized by deficits in social communication, and restricted, repetitive patterns of behavior, interests or activities. Based on the importance of early diagnosis for effective therapeutic intervention, several strategies have been employed for detection of the disorder. The artificial neural network (ANN) as a type of machine learning method is a common strategy. In the current study, we extracted genomic data for 487 ASD patients and 455 healthy individuals. All individuals were genotyped in certain single-nucleotide polymorphisms within retinoic acid-related orphan receptor alpha (RORA), gamma-aminobutyric acid type A receptor beta3 subunit (GABRB3), synaptosomal-associated protein 25 (SNAP25) and metabotropic glutamate receptor 7 (GRM7) genes. Subsequently, we used the "Keras" package to create and train the ANN model. For cross-validation, samples were divided into ten folds. In the training process, initially, the first fold was preserved for validation and the other folds were used to train the model. The validation fold was then used to evaluate model performance. The k-fold cross-validation method was used to ensure model generalizability and to prevent overfitting. Local interpretable model-agnostic explanations (LIME) were applied to explain model predictions at the data sample level. The output of loss function was evaluated in the training process for each fold in the k-fold cross-validation model. Finally, the number of losses was reduced to less than 0.6 after 200 epochs (except in two cases). The accuracy, sensitivity and specificity of our model were 73.67%, 82.75% and 63.95%, respectively. The area under the curve (AUC) was 80.59. Consequently, in the current study, we propose an ANN-based method for differentiating ASD status from healthy status with adequate power.

A promoter variant in ZNF804A decreasing its expression increases the risk of autism spectrum disorder in the Han Chinese population

Synaptic pathology may be one of the cellular substrates underlying autism spectrum disorder (ASD). ZNF804A is a transcription factor that can affect or regulate the expression of many candidate genes involved in ASD. It also localizes at synapses and regulates neuronal and synaptic morphology. So far, few reports have addressed possible associations between ZNF804A polymorphisms and ASD. This study aimed to investigate whether ZNF804A genetic variants contribute to ASD susceptibility and its possible pathological role in the disorder. We analyzed the relationship of two polymorphisms (rs10497655 and rs34714481) in ZNF804A promoter region with ASD in 854 cases versus 926 controls. The functional analyses of rs10497655 were then performed using real-time quantitative polymerase chain reaction, electrophoretic mobility shift assays, chromatin immunoprecipitation and dual-luciferase assays. The variant rs10497655 was significantly associated with ASD (P = 0.007851), which had a significant effect on ZNF804A expression, with the T risk allele homozygotes related with reduced ZNF804A expression in human fetal brains. HSF2 acted as a suppressor by down-regulating ZNF804A expression and had a stronger binding affinity for the T allele of rs10497655 than for the C allele. This was the first experiment to elucidate the process in which a disease-associated SNP affects the level of ZNF804A expression by binding with the upstream regulation factor HSF2. This result indicates that the rs10497655 allelic expression difference of ZNF804A during the critical period of brain development may have an effect on postnatal phenotypes of ASD. It reveals new roles of ZNF804A polymorphisms in the pathogenesis of psychiatric disorders.

ADGRL3 rs6551665 as a Common Vulnerability Factor Underlying Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder

Neurodevelopmental disorders are prevalent, frequently occur in comorbidity and share substantial genetic correlation. Previous evidence has suggested a role for the ADGRL3 gene in Attention-Deficit/Hyperactivity Disorder (ADHD) susceptibility in several samples. Considering ADGRL3 functionality in central nervous system development and its previous association with neurodevelopmental disorders, we aimed to assess ADGRL3 influence in early-onset ADHD (before 7 years of age) and Autism Spectrum Disorder (ASD). The sample comprises 187 men diagnosed with early-onset ADHD, 135 boys diagnosed with ASD and 468 male blood donors. We tested the association of an ADGRL3 variant (rs6551665) with both early-onset ADHD and ASD susceptibility. We observed significant associations between ADGRL3-rs6551665 on ADHD and ASD susceptibilities; we found that G-carriers were at increased risk of ADHD and ASD, in accordance with previous studies. The overall evidence from the literature, corroborated by our results, suggests that ADGRL3 might be involved in brain development, and genetic modifications related to it might be part of a shared vulnerability factor associated with the underlying neurobiology of neurodevelopmental disorders such as ADHD and ASD.

Metabotropic Glutamate Receptor 7: A New Therapeutic Target in Neurodevelopmental Disorders

Neurodevelopmental disorders (NDDs) are characterized by a wide range of symptoms including delayed speech, intellectual disability, motor dysfunction, social deficits, breathing problems, structural abnormalities, and epilepsy. Unfortunately, current treatment strategies are limited and innovative new approaches are sorely needed to address these complex diseases. The metabotropic glutamate receptors are a class of G protein-coupled receptors that act to modulate neurotransmission across many brain structures. They have shown great promise as drug targets for numerous neurological and psychiatric diseases. Moreover, the development of subtype-selective allosteric modulators has allowed detailed studies of each receptor subtype. Here, we focus on the metabotropic glutamate receptor 7 (mGlu₇) as a potential therapeutic target for NDDs. mGlu₇ is expressed widely throughout the brain in regions that correspond to the symptom domains listed above and has established roles in synaptic physiology and behavior. Single nucleotide polymorphisms and mutations in the GRM7 gene have been associated with idiopathic autism and other NDDs in patients. In rodent models, existing literature suggests that decreased mGlu₇ expression and/or function may lead to symptoms that overlap with those of NDDs. Furthermore, potentiation of mGlu₇ activity has shown efficacy in a mouse model of Rett syndrome. In this review, we summarize current findings that provide rationale for the continued development of mGlu₇ modulators as potential therapeutics.

Evaluation of antibodies to cytomegalovirus and Epstein-Barr virus in patients with autism spectrum disorder

Autism is a neurodevelopmental disease that manifested by a wide range of behavioral disorders. Although the etiology of autism is remained unknown but it is suggested that ASD have a complex etiology, including genetic and environmental factors, which may explain the observed different behavioral disorders in these patients. One of the proposed reasons for autism is viral infection in the early stages of development. The mechanism by which viral infection could lead to autism is still unclear.Previous studiesemphasized on the role of family membersof Herpesviruses in autism susceptibility. In this study, anti-Cytomegalovirus (CMV) and anti-Epstein-Barr virus (EBV) antibodies in the serum of 45 children with autism and 45 healthy individuals were evaluated. Serum samples were isolated from 5 ml blood of the patients and controls. Sandwich ELISA was used to quantitatively measure antibodies against the mentioned viruses. Results analyzed by SPSS software showed an increased amount of anti-CMV IgG and IgM antibodies in the blood of patients with Autism but not statistically significant (P< 0.05). The anti-EBV IgM antibody in the blood of patients with Autism was not only increased but also statistically significant (P< 0.05), however, the IgG level against EBV in the serum of ASD patients showed no significant difference in comparison to healthy controls. So it can be said that although the mechanisms of viral infection in autism is unknown, but probably EBV infection is associated with an increased risk of autism.

Meta-analysis of GABRB3 Gene Polymorphisms and Susceptibility to Autism Spectrum Disorder

Several lines of evidence have suggested that the GABA receptor subunit β3 (GABRB3) gene is a genetic contributor in the autism spectrum disorder (ASD). The aberrant expression of GABRB3 is reported in ASD patients which may be a consequence of the presence of certain genetic variants in the promoter region of the gene. The associations between single-nucleotide polymorphisms (SNPs) within this gene and ASD have been analyzed in previous studies. However, the results are conflicting. In the present study, we performed a meta-analysis on association between two SNPs located in the promoter region of GABRB3 gene (rs4906902 and rs20317) and ASD. The literature search was performed based on criteria provided by the meta-analysis of observational studies in epidemiology (MOOSE). The association between mentioned SNPs and ASD was calculated using pooled odd ratios (ORs) and 95% confidence intervals. The result of the present meta-analysis indicates that neither rs4906902 nor rs20317 are significantly associated with the risk of ASD. The underlying mechanism of the aberrant expression of GABRB3 gene in ASD patients should be investigated in other biological levels.

Association of HLA alleles with autism

BACKGROUND

Autism spectrum disorders (ASD) are a group of heterogeneous neurodevelopmental disorders known by impaired social interaction and activities and abnormal repetitive behavior. As a multifactorial disorder, several genetic and immunological factors have been shown to be implicated in its pathogenesis.

METHODS

Among them are certain human leukocyte antigen (HLA) alleles. In the current study, we genotyped HLA-A, -B & DRB alleles in 103 Iranian ASD patients and 180 age, gender, and ethnic-matched healthy controls.

RESULTS

After Boferroni correction no allele or haplotype was associated with genetic susceptibility to ASD in Iranian population.

CONCLUSION

Future studies are needed to assess contribution of immunological factors such as HLA alleles in ASD pathogenesis.

Retinoic acid-related orphan receptor alpha (RORA) variants are associated with autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with various epidemiologic, genetic, epigenetic, and environmental factors being associated with it. The observed sex bias in ASD towards male has prompted investigators to propose sex-dependent mechanisms for ASD. Retinoic acid-related orphan receptor-alpha (RORA) is a new autism candidate gene that has been shown to be differentially regulated by male and female hormones. Previous studies have shown deregulation of its expression in the prefrontal cortex and the cerebellum of ASD patients. In the present study we aimed at identification of the possible associations between two functional polymorphisms in the RORA gene (rs11639084 and rs4774388) and the risk of ASD in 518 Iranian ASD patients and 472 age, gender, and ethnic-matched healthy controls by means of tetra primer-amplification refractory mutation system-PCR. The allele and genotype frequencies of rs11639084 were not significantly different between patients and controls. However, the allele frequencies of rs4774388 showed significant overrepresentation of T allele in patients compared with controls (P = 0.04, OR (95% CI) =1.21 (1.01-1.46)). The rs4774388-TT genotype was significantly higher in patients compared with controls and was associated with ASD risk in dominant inheritance model (P = 0.04, OR (95% CI) =0.77 (0.59-0.99)). Haplotype analysis showed significant association of two estimated blocks of rs11639084/ rs4774388 with ASD risk. Consequently, the present data provide further evidence for RORA participation in the pathogenesis of ASD.

Blood assessment of the expression levels of matrix metalloproteinase 9 (MMP9) and its natural inhibitor, TIMP1 genes in Iranian schizophrenic patients

Schizophrenia (SCZ) is the most severe chronic mental disorder characterized by abnormal social behavior and disrupted emotions and thought. Like other complex neuropsychological disease, SCZ is caused by a combination of genetic and environmental factors but with a high concordance rate. So far, different genetic factors are revealed to be associated with increased risk of developing SCZ. One of the best ways to investigate the genetic basis of the complex disease is to discover the genetic underlying mechanisms of the defective clinical aspects of the patients. In this regard, genes involved in the developmental mechanisms of the brain such as long-term potentiation (LTP) process that is the basis of synaptic plasticity, memory and learning are considered as strong candidates for SCZ. The aim of the present study was to evaluate the expression levels of two genes that are involved in the LTP regulation in the developing and adult brain, Matrix metallopeptidase9 (MMP9) and TIMP metallopeptidase inhibitor 1 (TIMP1) genes in a blood assessment of schizophrenic patients in comparison to healthy controls by means of quantitative real time PCR. The results of the study showed a significant difference in MMP9/TIPM1 ratio between SCZ patients and healthy controls (P = 0.01). However, no significant difference was detected in the expression level of individual MMP9 and TIMP1 genes in SCZ patients versus healthy controls either in total numbers of subject or in sex based subgroups. Considering the relatively small sample size of the current study, there is a need to replicate this study with further investigations about the mechanism of association of these genes and their functions in the pathogenesis of the SCZ.

Ras-like without CAAX 2 (RIT2): a susceptibility gene for autism spectrum disorder

Ras-like without CAAX2 (RIT2) which encodes a GTP-binding protein has recently been reported as a new susceptibility gene for Autism Spectrum Disorders (ASD) in a genome-wide association study. Since the gene is suggested to be involved in the pathogenesis of different neurological diseases, we investigated the association of two single nucleotide polymorphisms (SNP) rs16976358 and rs4130047 of this gene with ASD in Iranian patients. A total of 1004 individuals, comprising 532 ASD cases and 472 healthy subjects participated in this study. Allele frequency analyses showed significant over-presentation of rs16976358-C allele in cases versus controls (P < 0.0001). In addition, rs16976358 CC genotype (OR (95% CI) =3.57(1.72-7.69) and P < 0.0001) and rs4130047 CC genotype (OR (95% CI) =0.64(0.43-0.97) and P = 0.035) were associated with ASD in recessive inheritance model. Besides, haplotype analysis demonstrated an association between the C/T haplotype block (rs16976358/rs4130047) and ASD (OR (95%CI) = 0.44 (0.31-0.62), P < 0.0001). Altogether, our findings provided additional confirmation for the RIT2 gene participation in ASD risk and suggested the rs16976358 variant as a possible genetic risk factor for this disorder.

The association of CNTNAP2 rs7794745 gene polymorphism and autism in Iranian population

Autism is a heterogeneous and multifactorial disease that results from the interaction between genetic vulnerability and environmental factors. Several studies showed that many of genes that play role in autism are component of signaling networks that regulate growth and synaptic plasticity, play an important role in the etiology of autism. Contactin associated-like 2 (CNTNAP2) gene is a member of the superfamily of synaptic adhesion proteins and encodes a scaffold protein called CASPR2 that is involved in the interaction of neuron-glia and clusters K⁺ channels in myelinated axons. CNTNAP2 is highly expressed during the nervous system development. In this study the association of rs7794745 CNTNAP2 gene polymorphism and autism was investigated. Two hundred patients with autism and 260 healthy individuals were included in this study. Genomic DNA was extracted from peripheral blood cells. Genotypes were analyzed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Statistical analysis was performed using the software MedCalc (12.1). The genotype frequencies of AA, AT, TT were 35.3%, 50.7% and 13.8% in controls and these values were 32% and 68% and 0% in patients with autism, respectively (P=0.0001) (OR=0.01, 95% CI 0.001-0.32). The frequency of A and T alleles were 66%, 34% in patients and 60%, 40% in controls, respectively (P=0.11). The results of this study showed that there is a significant association between rs7794745 CNTNAP2 gene polymorphism and autism in the studied population. However, to obtain a definitive conclusion larger studies with more patients and controls are needed to confirm the results.

Synaptosome-Associated Protein 25 (SNAP25) Gene Association Analysis Revealed Risk Variants for ASD, in Iranian Population

Autism spectrum disorder (ASD) is a common, complex neurological condition, affecting approximately 1% of people worldwide. Monogenic neurodevelopmental disorders which showed autistic behavior patterns have suggested synaptic dysfunction, as a key mechanism in the pathophysiology of ASD. Subsequently, genes involved in synaptic signaling have been investigated with a priority for candidate gene studies. A synaptosomal-associated protein 25 (SNAP25) gene plays a crucial role in the central nervous system, contributing to exocytosis by targeting and fusion of vesicles to the cell membrane. Studies have shown a correlation between aberrant expression of the SNAP25 and a variety of brain diseases. Single nucleotide polymorphisms (SNPs) in this gene are associated with several psychiatric diseases, such as bipolar, schizophrenia, and attention-deficit/hyperactivity disorder. The aim of the present study was to investigate whether polymorphisms (rs3746544 and rs1051312) in the regulatory 3'-untranslated region (3'UTR) of the SNAP25 gene have an association with ASD in unrelated Iranian case (N = 524)-control (N = 472) samples. We observed robust association of the rs3746544 SNP and ASD patients, in both allele and haplotype-based analyses. Our results supported the previous observations and indicated a possible role for SNAP25 polymorphisms as susceptibility genetic factors involved in developing ASD.

FOXP3 gene variations and susceptibility to autism: A case-control study

Autism Spectrum Disorders (ASD) are a group of heterogeneous neurodevelopmental disorders associated with immune system dysregulation. There are supporting evidences for the role of Forkhead Box P3 (FOXP3) gene as a lineage specification factor of regulatory T cells in the pathogenesis of ASD. The aim of this study was to explore possible relationship between genetic variants rs2232365 and rs3761548 of FOXP3 and ASD in 523 ASD patients versus 472 control individuals. Allele frequency analyses showed significant overpresentation of rs2232365-G allele in cases versus controls. In addition, rs2232365 GG genotype was associated with ASD in dominant inheritance model. Haplotype analysis revealed no significant association of any estimated block of rs2232365/rs3761548 with ASD. Our study indicated that rs2232365 is associated with ASD.