Fmr1 deficiency promotes age-dependent alterations in the cortical synaptic proteome

Fragile X syndrome (FXS) is an X-linked neurodevelopmental disorder characterized by severe intellectual disability and other symptoms including autism. Although caused by the silencing of a single gene, Fmr1 (fragile X mental retardation 1), the complexity of FXS pathogenesis is amplified because the encoded protein, FMRP, regulates the activity-dependent translation of numerous mRNAs. Although the mRNAs that associate with FMRP have been extensively studied, little is known regarding the proteins whose expression levels are altered, directly or indirectly, by loss of FMRP during brain development. Here we systematically measured protein expression in neocortical synaptic fractions from Fmr1 knockout (KO) and wild-type (WT) mice at both adolescent and adult stages. Although hundreds of proteins are up-regulated in the absence of FMRP in young mice, this up-regulation is largely diminished in adulthood. Up-regulated proteins included previously unidentified as well as known targets involved in synapse formation and function and brain development and others linked to intellectual disability and autism. Comparison with putative FMRP target mRNAs and autism susceptibility genes revealed substantial overlap, consistent with the idea that the autism endophenotype of FXS is due to a “multiple hit” effect of FMRP loss, particularly within the PSD95 interactome. Through studies of de novo protein synthesis in primary cortical neurons from KO and WT mice, we found that neurons lacking FMRP produce nascent proteins at higher rates, many of which are synaptic proteins and encoded by FMRP target mRNAs. Our results provide a greatly expanded view of protein changes in FXS and identify age-dependent effects of FMRP in shaping the neuronal proteome.

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Case report : a novel ASXL3 gene variant in a Sudanese boy

BMC Pediatrics ◽

10.1186/s12887-021-03038-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Ke Wu ◽

Yan Cong

Keyword(s):

Intellectual Disability ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

De Novo ◽

Neurodevelopmental Disorder ◽

Psychomotor Development ◽

Gene Variant ◽

Feeding Difficulties ◽

Severe Intellectual Disability ◽

Whole Exome

Abstract Background Bainbridge-Ropers syndrome (BRPS) [OMIM#615485] is a neurodevelopmental disorder, characterized by delayed psychomotor development with generalized hypotonia, moderate to severe intellectual disability, poor or absent speech, feeding difficulties, growth failure, dysmorphic craniofacial features and minor skeletal features. The aim of this study was to investigate the genetic etiology of a Sudanese boy with severe developmental delay, intellectual disability, and craniofacial phenotype using trio-based whole-exome sequencing. To our knowledge, no patients with ASXL3 gene variant c.3043C>T have been reported detailedly in literature. Case presentation The patient (male, 3 years 6 months) was the first born of a healthy non-consanguineous couple originating from Sudan, treated for “psychomotor retardation” for more than 8 months in Yiwu. The patient exhibited severely delayed milestones in physiological and intellectual developmental stages, language impairment, poor eye-contact, lack of subtle motions of fingers, fear of claustrophobic space, hypotonia, clinodactyly, autistic features. Peripheral blood samples were collected from the patient and his parents. Trio-based whole-exome sequencing(Trio-WES) identified a de novo heterozygous ASXL3 gene variant c.3043C>T;p.Q1015X. Sanger sequencing verified variants of this family. Conclusion Trio-WES analysis identified a de novo nonsense variant (c.3043C>T) of ASXL3 gene in a Sudanese boy. To our knowledge, the patient with this variant has not been reported previously in literature. This study presents a new case for ASXL3 gene variants, which expanded the mutational and phenotypic spectrum.

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A New Case of de novo Variant c.892C>T (p.Arg298Trp) in NACC1: A First Case Report From China

Frontiers in Pediatrics ◽

10.3389/fped.2021.754261 ◽

2021 ◽

Vol 9 ◽

Author(s):

Baiyu Lyu ◽

Yan Dong ◽

Juan Kang

Keyword(s):

Intellectual Disability ◽

Congenital Cataract ◽

De Novo ◽

Neurodevelopmental Disorder ◽

Brain Mri ◽

Case Presentation ◽

Feeding Difficulties ◽

Severe Intellectual Disability ◽

First Case ◽

Infantile Epilepsy

Background: The nucleus accumbens associated 1 (NACC1) gene is a transcription factor member of the BTB/POZ family. A de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1 may define a syndrome characterized by intellectual disability, infantile epilepsy, congenital cataract, and feeding difficulties.Case Presentation: We report a new case with a neurodevelopmental disorder characterized by severe intellectual disability, infantile epilepsy, congenital cataract, and feeding difficulties. Brain MRI reveals brain dysplasia. We observe a de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1 gene in this case. Now, the child regularly goes to the hospital for rehabilitation training (once a month). Sodium Valproate (10 mg/kg/day) and Clobazam (10 mg/kg/day) are used in the treatment of epilepsy. A total of three articles were screened, and two papers were excluded. The search revealed one article related to a syndrome caused by a de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1; they screened the main clinical features of eight cases of a syndrome, which were summarized and analyzed.Conclusions: The NACC1 gene is a member of the BTB/POZ family of transcription factors. A de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1 may define a syndrome characterized by intellectual disability, infantile epilepsy, congenital cataract, and feeding difficulties. At present, there is no effective cure. In the future, we need more cases to determine the phenotype–genotype correlation of NACC1 variants. Many questions remain to be answered, and many challenges remain to be faced. Future transcriptional studies may further clarify this rare, recurrent variant, and could potentially lead to targeted therapies.

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SYT1-associated neurodevelopmental disorder: a case series

Brain ◽

10.1093/brain/awy209 ◽

2018 ◽

Vol 141 (9) ◽

pp. 2576-2591 ◽

Cited By ~ 29

Author(s):

Kate Baker ◽

Sarah L Gordon ◽

Holly Melland ◽

Fabian Bumbak ◽

Daniel J Scott ◽

...

Keyword(s):

Intellectual Disability ◽

De Novo ◽

Neurodevelopmental Disorder ◽

Case Series ◽

Missense Mutations ◽

Severe Intellectual Disability ◽

Specific Manner ◽

Synaptotagmin 1 ◽

Presynaptic Vesicle ◽

Key Features

Baker, Gordon et al. present the first international case series describing the neurodevelopmental disorder associated with Synaptotagmin 1 (SYT1) de novo missense mutations. Key features include movement abnormalities, severe intellectual disability, and hallmark EEG alterations. Expression of patients’ SYT1 mutations in mouse neurons disturbs presynaptic vesicle dynamics in a mutation-specific manner.

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IL1RAPL1 Gene Deletion in a Female Patient with Developmental Delay and Continuous Spike-Wave during Sleep

Journal of Pediatric Epilepsy ◽

10.1055/s-0041-1731816 ◽

2021 ◽

Author(s):

Evan Jiang ◽

Mark P. Fitzgerald ◽

Katherine L. Helbig ◽

Ethan M. Goldberg

Keyword(s):

Intellectual Disability ◽

Developmental Delay ◽

Synapse Formation ◽

De Novo ◽

Interleukin 1 ◽

Autism Spectrum ◽

Neurological Dysfunction ◽

Behavioral Disorder ◽

Clinical Genetic ◽

Severe Intellectual Disability

AbstractInterleukin-1 receptor accessory protein-like 1 (IL1RAPL1) encodes a protein that is highly expressed in neurons and has been shown to regulate neurite outgrowth as well as synapse formation and synaptic transmission. Clinically, mutations in or deletions of IL1RAPL1 have been associated with a spectrum of neurological dysfunction including autism spectrum disorder and nonsyndromic X-linked developmental delay/intellectual disability of varying severity. Nearly all reported cases are in males; in the few reported cases involving females, the clinical presentation was mild or the deletion was identified in phenotypically normal carriers in accordance with X-linked inheritance. Using genome-wide microarray analysis, we identified a novel de novo 373 kb interstitial deletion of the X chromosome (Xp21.1-p21.2) that includes exons 4 to 6 of the IL1RAPL1 gene in an 8-year-old girl with severe intellectual disability and behavioral disorder with a history of developmental regression. Overnight continuous video electroencephalography revealed electrical status epilepticus in sleep (ESES). This case expands the clinical genetic spectrum of IL1RAPL1-related neurodevelopmental disorders and highlights a new genetic association of ESES.

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SENP1 in the retrosplenial agranular cortex regulates core autistic-like symptoms in mice

10.1101/2021.01.24.427868 ◽

2021 ◽

Author(s):

Kan Yang ◽

Yuhan Shi ◽

Xiujuan Du ◽

Yuefang Zhang ◽

Shifang Shan ◽

...

Keyword(s):

Social Interaction ◽

De Novo ◽

Fragile X ◽

Neurodevelopmental Disorder ◽

Autism Spectrum ◽

Repetitive Behaviors ◽

Genetic Components ◽

Truncating Mutation ◽

Synaptic Functions ◽

Core Symptoms

AbstractAutism spectrum disorder (ASD) is a highly heritable complex neurodevelopmental disorder. While the core symptoms of ASD are defects of social interaction and repetitive behaviors, over 50% of ASD patients have comorbidity of intellectual disabilities (ID) or developmental delay (DD), raising the question whether there are genetic components and neural circuits specific for core symptoms of ASD. Here, by focusing on ASD patients who do not show compound ID or DD, we identified a de novo heterozygous gene-truncating mutation of the Sentrin-specific peptidase1 (SENP1) gene, coding the small ubiquitin-like modifiers (SUMO) deconjugating enzyme, as a potentially new candidate gene for ASD. We found that Senp1 haploinsufficient mice exhibited core symptoms of autism such as deficits in social interaction and repetitive behaviors, but normal learning and memory ability. Moreover, we found that the inhibitory and excitatory synaptic functions were severely affected in the retrosplenial agranular (RSA) cortex of Senp1 haploinsufficient mice. Lack of Senp1 led to over SUMOylation and degradation of fragile X mental retardation protein (FMRP) proteins, which is coded by the FMR1 gene, also implicated in syndromic autism. Importantly, re-introducing SENP1 or FMRP specifically in RSA fully rescued the defects of synaptic functions and core autistic-like symptoms of Senp1 haploinsufficient mice. Taken together, these results elucidate that disruption of the SENP1-FMRP regulatory axis in the RSA may cause core autistic symptoms, which further provide a candidate brain region for therapeutic intervene of ASD by neural modulation approaches.

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Recurrent de novo missense variants in GNB2 can cause syndromic intellectual disability

Journal of Medical Genetics ◽

10.1136/jmedgenet-2020-107462 ◽

2021 ◽

pp. jmedgenet-2020-107462

Author(s):

Natalie B Tan ◽

Alistair T Pagnamenta ◽

Matteo P Ferla ◽

Jonathan Gadian ◽

Brian HY Chung ◽

...

Keyword(s):

Intellectual Disability ◽

G Proteins ◽

De Novo ◽

Neurodevelopmental Disorder ◽

Missense Variant ◽

Cellular Functions ◽

Missense Variants ◽

Neurodevelopmental Disease ◽

Genes Encoding ◽

International Data

PurposeBinding proteins (G-proteins) mediate signalling pathways involved in diverse cellular functions and comprise Gα and Gβγ units. Human diseases have been reported for all five Gβ proteins. A de novo missense variant in GNB2 was recently reported in one individual with developmental delay/intellectual disability (DD/ID) and dysmorphism. We aim to confirm GNB2 as a neurodevelopmental disease gene, and elucidate the GNB2-associated neurodevelopmental phenotype in a patient cohort.MethodsWe discovered a GNB2 variant in the index case via exome sequencing and sought individuals with GNB2 variants via international data-sharing initiatives. In silico modelling of the variants was assessed, along with multiple lines of evidence in keeping with American College of Medical Genetics and Genomics guidelines for interpretation of sequence variants.ResultsWe identified 12 unrelated individuals with five de novo missense variants in GNB2, four of which are recurrent: p.(Ala73Thr), p.(Gly77Arg), p.(Lys89Glu) and p.(Lys89Thr). All individuals have DD/ID with variable dysmorphism and extraneurologic features. The variants are located at the universally conserved shared interface with the Gα subunit, which modelling suggests weaken this interaction.ConclusionMissense variants in GNB2 cause a congenital neurodevelopmental disorder with variable syndromic features, broadening the spectrum of multisystem phenotypes associated with variants in genes encoding G-proteins.

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Identification of FMRP target mRNAs in the developmental brain: FMRP might coordinate Ras/MAPK, Wnt/β-catenin, and mTOR signaling during corticogenesis

Molecular Brain ◽

10.1186/s13041-020-00706-1 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Cristine R. Casingal ◽

Takako Kikkawa ◽

Hitoshi Inada ◽

Yukio Sasaki ◽

Noriko Osumi

Keyword(s):

Brain Development ◽

Rna Binding ◽

Fragile X ◽

Autism Spectrum ◽

Mtor Signaling ◽

Mitogen Activated Protein Kinase ◽

Sequencing Analysis ◽

Embryonic Brain ◽

Target Mrnas ◽

Mrna Targets

AbstractCorticogenesis is one of the most critical and complicated processes during embryonic brain development. Any slight impairment in corticogenesis could cause neurodevelopmental disorders such as Fragile X syndrome (FXS), of which symptoms contain intellectual disability (ID) and autism spectrum disorder (ASD). Fragile X mental retardation protein (FMRP), an RNA-binding protein responsible for FXS, shows strong expression in neural stem/precursor cells (NPCs) during corticogenesis, although its function during brain development remains largely unknown. In this study, we attempted to identify the FMRP target mRNAs in the cortical primordium using RNA immunoprecipitation sequencing analysis in the mouse embryonic brain. We identified 865 candidate genes as targets of FMRP involving 126 and 118 genes overlapped with ID and ASD-associated genes, respectively. These overlapped genes were enriched with those related to chromatin/chromosome organization and histone modifications, suggesting the involvement of FMRP in epigenetic regulation. We further identified a common set of 17 FMRP “core” target genes involved in neurogenesis/FXS/ID/ASD, containing factors associated with Ras/mitogen-activated protein kinase, Wnt/β-catenin, and mammalian target of rapamycin (mTOR) pathways. We indeed showed overactivation of mTOR signaling via an increase in mTOR phosphorylation in the Fmr1 knockout (Fmr1 KO) neocortex. Our results provide further insight into the critical roles of FMRP in the developing brain, where dysfunction of FMRP may influence the regulation of its mRNA targets affecting signaling pathways and epigenetic modifications.

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Specific effect of the fragile-X mental retardation-1 gene (FMR1) on white matter microstructure

The British Journal of Psychiatry ◽

10.1192/bjp.bp.114.151654 ◽

2015 ◽

Vol 207 (2) ◽

pp. 143-148 ◽

Cited By ~ 11

Author(s):

Tamar Green ◽

Naama Barnea-Goraly ◽

Mira Raman ◽

Scott S. Hall ◽

Amy A. Lightbody ◽

...

Keyword(s):

Genetic Variation ◽

Intellectual Disability ◽

White Matter ◽

Neurodevelopmental Disorders ◽

Fragile X ◽

Neurodevelopmental Disorder ◽

Specific Effect ◽

Radial Diffusivity ◽

Fragile X Mental Retardation ◽

White Matter Microstructure

BackgroundFragile-X syndrome (FXS) is a neurodevelopmental disorder associated with intellectual disability and neurobiological abnormalities including white matter microstructural differences. White matter differences have been found relative to neurotypical individuals.AimsTo examine whether FXS white matter differences are related specifically to FXS or more generally to the presence of intellectual disability.MethodWe used voxel-based and tract-based analytic approaches to compare individuals with FXS (n = 40) with gender- and IQ-matched controls (n = 30).ResultsIndividuals with FXS had increased fractional anisotropy and decreased radial diffusivity values compared with IQ-matched controls in the inferior longitudinal, inferior fronto-occipital and uncinate fasciculi.ConclusionsThe genetic variation associated with FXS affects white matter microstructure independently of overall IQ. White matter differences, found in FXS relative to IQ-matched controls, are distinct from reported differences relative to neurotypical controls. This underscores the need to consider cognitive ability differences when investigating white matter microstructure in neurodevelopmental disorders.

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A Novel SETBP1 Gene Disruption by a De Novo Balanced Translocation in a Patient with Speech Impairment, Intellectual, and Behavioral Disorder

Journal of Pediatric Genetics ◽

10.1055/s-0040-1715639 ◽

2020 ◽

Author(s):

Ivona Vrkić Boban ◽

Futoshi Sekiguchi ◽

Mirela Lozić ◽

Noriko Miyake ◽

Naomichi Matsumoto ◽

...

Keyword(s):

Intellectual Disability ◽

Autosomal Dominant ◽

De Novo ◽

Chromosomal Abnormalities ◽

Chromosome Translocation ◽

Behavioral Disorder ◽

Behavioral Difficulties ◽

Speech Impairment ◽

Balanced Translocation ◽

Severe Intellectual Disability

AbstractBalanced chromosomal abnormalities (BCAs) can disrupt gene function resulting in disease. To date, BCA disrupting the SET binding protein 1 (SETBP1) gene has not been reported. On the other hand, de novo heterozygous variants in the highly conserved 11-bp region in SETBP1 can result in the Schinzel–Giedion syndrome. This condition is characterized by severe intellectual disability, a characteristic face, and multiple-system anomalies. Further other types of mutations involving SETBP1 are associated with a different phenotype, mental retardation, autosomal dominant 29 (MRD29), which has mild dysmorphic features, developmental delay, and behavioral disorders. Here we report a male patient who has moderate intellectual disability, mild behavioral difficulties, and severe expressive speech impairment resulting from a de novo balanced chromosome translocation, t(12;18)(q22;q12.3). By whole genome sequencing, we determined the breakpoints at the nucleotide level. The 18q12.3 breakpoint was located between exons 2 and 3 of SETBP1. Phenotypic features of our patient are compatible with those with MRD29. This is the first reported BCA disrupting SETBP1.

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