A commonly carried genetic variant, rs9616915, in SHANK3 gene is associated with a reduced risk of autism spectrum disorder: replication in a Chinese population

SHANK3 genetic polymorphism and susceptibility to ASD: evidence from molecular, in silico, and meta-analysis approaches

BACKGROUND

The SHANK3 gene encodes a master synaptic scaffolding protein at the excitatory synapse's postsynaptic density, which is predominantly responsible for constructing a synapse, maintaining synaptic structure, and functions. Recently, evidence from rare mutations and copy number variation provided an important clue about SHANK3 which acts as a strong candidate gene in the pathogenesis of Autism Spectrum Disorder (ASD).

MATERIALS AND METHODS

To investigate potential allelic variants for the SHANK3 (rs9616915) gene as a genetic risk factor, we performed PCR-RFLP analysis and Sanger sequencing for 90 ASD and 90 healthy subjects. Moreover, to understand the functional and structural impacts of our selected non-synonymous SHANK3 SNP rs9616915, we have performed an in silico analysis. Subsequently, a meta-analysis of rs9616915 with a total of 6 eligible studies (including the present study) containing a total of 795 cases and 12,947 controls was obtained from a comprehensive online database search to evaluate the overall association with ASD.

RESULTS

Our retrieved data, such as Pearson's chi-square test (p = 0.081) as well as logistic regression analysis of co-dominant (p = 0.1131), dominant (p = 0.3656) and recessive models (p = 0.0569) speculated no significant association between rs9616915 and our studied sample. Interestingly, by in silico analysis, we have observed two hydrogen bonds between amino acids instead of one hydrogen bond in the protein structure of rs9616915, which indicates this mutant structure could affect the proteins' stability. The findings of the meta-analysis revealed that four genetic association models were associated with ASD susceptibility.

CONCLUSIONS

Our study suggested that targeted SHANK3 SNP of interest rs9616915 might not be associated with ASD in the southern part of the Bangladeshi population.

SHANK3 Genotype Mediates Speech and Language Phenotypes in a Nonclinical Population

Mutations affecting the synaptic-scaffold gene SHANK3 represent the most common genetic causes of autism with intellectual disability, accounting for about 1-2% of cases. Rare variants of this gene have also been associated with schizophrenia, and its deletion results in the autistic condition known as Phelan–McDermid syndrome. Despite the importance of SHANK3 as a paradigmatic gene mediating neurodevelopmental disorders, its psychological effects in nonclinical populations have yet to be studied. We genotyped the nonsynonymous, functional SHANK3 SNP rs9616915 in a large population of typical individuals scored for autism spectrum traits (the Autism Quotient, AQ) and schizotypy spectrum traits (the Schizotypal Personality Questionnaire, SPQ-BR). Males, but not females, showed significant genotypic effects for the SPQ-BR subscale associated with speech and language: Odd Speech. These findings, in conjunction with animal model studies showing vocalization and auditory effects of SHANK3 mutations, and studies indicating severe language alterations and speech-associated white matter tract abnormalities in Phelan–McDermid syndrome, suggest that SHANK3 differentially affects the development and expression of human language and speech. Imaging genetic and speech-language studies of typical individuals carrying different genotypes of rs9616915 should provide novel insights into the neurological and psychological bases of speech and language alterations among individuals with SHANK3 mutations and Phelan–McDermid syndrome.

Association of SHANK3 Gene Polymorphism and Parkinson Disease in the North of Iran

INTRODUCTION

Parkinson Disease (PD), the second most common chronic neurodegenerative disorder, is characterized by tremor, bradykinesia, rigidity, and postural instability. SHANK3 (SH3 and multiple ankyrin repeat domain 3) belongs to the extremely conserved ProSAP/Shank family of synaptic scaffolding proteins. Meanwhile, rs9616915 is a non-synonymous SNP (T>C) located in the exon 6 of the SHANK3 gene, which induces substitution of isoleucine to threonine and affects the function of the resulted protein. The present study aimed to evaluate whether rs9616915 polymorphism of SHANK3 is involved in the susceptibility to PD.

METHODS

The study subjects were 100 patients diagnosed with PD and 100 control volunteers. The obtained samples were evaluated by the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

A significant association was found in genotype distribution between cases and controls. Individuals with TC genotype had increased risk of PD (P=0.035, OR=1.98, 95% CI=1.04 - 3.74). No significant difference was found in allele distribution (P=0.7).

CONCLUSION

The findings suggest that the SHANK3 rs9616915 polymorphism is associated with an increased risk of PD in the population. Further studies are needed to confirm the role of the SHANK3 gene in PD.

Genetic variability in scaffolding proteins and risk for schizophrenia and autism-spectrum disorders: a systematic review

Scaffolding proteins represent an evolutionary solution to controlling the specificity of information transfer in intracellular networks. They are highly concentrated in complexes located in specific subcellular locations. One of these complexes is the postsynaptic density of the excitatory synapses. There, scaffolding proteins regulate various processes related to synaptic plasticity, such as glutamate receptor trafficking and signalling, and dendritic structure and function. Most scaffolding proteins can be grouped into 4 main families: discs large (DLG), discs-large-associated protein (DLGAP), Shank and Homer. Owing to the importance of scaffolding proteins in postsynaptic density architecture, it is not surprising that variants in the genes that code for these proteins have been associated with neuropsychiatric diagnoses, including schizophrenia and autism-spectrum disorders. Such evidence, together with the clinical, neurobiological and genetic overlap described between schizophrenia and autism-spectrum disorders, suggest that alteration of scaffolding protein dynamics could be part of the pathophysiology of both. However, despite the potential importance of scaffolding proteins in these psychiatric conditions, no systematic review has integrated the genetic and molecular data from studies conducted in the last decade. This review has the following goals: to systematically analyze the literature in which common and/or rare genetic variants (single nucleotide polymorphisms, single nucleotide variants and copy number variants) in the scaffolding family genes are associated with the risk for either schizophrenia or autism-spectrum disorders; to explore the implications of the reported genetic variants for gene expression and/or protein function; and to discuss the relationship of these genetic variants to the shared genetic, clinical and cognitive traits of schizophrenia and autism-spectrum disorders.

[Dichotomous classification of autism spectrum disorders: syndromal and non-syndromal forms]

In foreign literature on research into the etiopathogenesis of autism spectrum disorders (ASDs), the division of this group of diseases into two forms is getting more and more frequent. These two forms are 'syndromal' and 'non-syndromal' forms of autistic disorders. The literature review aims to cover the issues of the dichotomous classification of ASDs based on the genetic and molecular psychiatric views on the etiopathogenesis of this group of diseases. It also covers the purpose of this classification, the opportunities of its usage in routine clinical practice and the network resources, which allow classifying a form of ASD correctly. Special attention is paid to the multidisciplinary approach to dichotomous classification and its difference from the clinical view on the systematization of autism and the importance of this method for selection of target therapy.

Evaluating the association between the SHANK3 gene and bipolar disorder

BACKGROUND

Previous studies have shown that the genes involved in synaptic density and plasticity were downregulated in bipolar disorder (BD) postmortem brains. The SHANK3 (SH3 and multiple ankyrin repeat domain 3) protein is a scaffold protein enriched in the postsynaptic density of excitatory synapses, and recent findings were suggestive of a possible role of SHANK3 in the development of BD. In this study, we aimed to evaluate the genetic association between the gene encoding SHANK3 (SHANK3) and BD in Han Chinese.

METHODS

Ten variants in SHANK3 were genotyped among 1482 individuals with or without BD. We measured the mRNA expression level of SHANK3 in patients with BD and controls. We then performed an eQTL analysis.

RESULTS

In our sample set, there were no significant differences in allele, genotype and haplotype frequencies between the BD and control groups. Our results showed no significant difference in the level of peripheral SHANK3 expression between the BD patients and healthy controls. Further eQTL analysis showed that rs9616915 has functional effect on SHANK3 expression in the hippocampus.

CONCLUSION

This study does not provide evidence for a major role of SHANK3 in the pathogenesis of BD.

The association of SHANK3 gene polymorphism and autism

BACKGROUND

Autism spectrum disorder (ASD) and Autism are both general terms for a group of complex disorders of brain development. These disorders are characterized by difficulties in social interaction, verbal and nonverbal communication and repetitive behaviors. Many genes have been shown to be involved in Autism. SHANK3 (SH3 and multiple ankyrin repeat domain 3) is a member of the highly conserved Shank/ProSAP family of synaptic scaffolding proteins. SHANK3 is suggested as a strong candidate gene for the pathogenesis of Autism and its loss results in disruption of synaptic function. The rs9616915 SNP, which directly affects SHANK3 gene function of splicing regulation and protein structure damage, is a non-synonymous SNP (T>C) that found in exon 6, leads to substitution of Isoleucine to Threonine. The present study was aimed to evaluate whether rs9616915 polymorphism of SHANK3 are related with the susceptibility to Autism.

METHODS

Samples were obtained from 90 patients diagnosed with Autism and 100 controls subjects and genotyped by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The results of this study showed that there is a significant association in genotype distribution between cases and controls (P=0.0001).

RESULTS

Our findings revealed that individuals with TC genotypes were associated with increased risk of Autism disorder (OR=4.35, 95% CI: 2.15-8.80, P=0.0001) but no significant differences were found in allele distributions (P=0.1).

CONCLUSIONS

Our results indicated that the SHANK3 rs9616915 polymorphism is associated with increased risk of Autism. Larger studies with more patients and controls are needed to confirm the results.

Association analysis of genetic variant of rs13331 in PSD95 gene with autism spectrum disorders: A case-control study in a Chinese population

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by high heritability. Recently, autism, the most profound form of ASD, has been increasingly attributed to synaptic abnormalities. Postsynaptic density 95 (PSD95), encoding PSD protein-95, was found essential for synaptic formation, maturation and plasticity at a PSD of excitatory synapse. It is possibly a crucial candidate gene for the pathogenesis of ASD. To identify the relationship between the rs13331 of PSD95 gene and ASD, we performed a case-control study in 212 patients and 636 controls in a Chinese population by using a polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP) assay. The results showed that in genetic analysis of the heterozygous model, an association between the T allele of the rs13331 and ASD was found in the dominant model (OR=1.709, 95% CI 1.227-2.382, P=0.002) and the additive model (OR=1.409, 95% CI=1.104-1.800, P=0.006). Our data indicate that the genetic mutation C>T at the rs13331 in the PSD95 gene is strikingly associated with an increased risk of ASD.