scholarly journals A novel TUBG1 mutation with neurodevelopmental disorder caused by malformations of cortical development

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ru Shen ◽  
Zhen Zhang ◽  
Yu Zhuang ◽  
Xiaohong Yang ◽  
Lifen Duan
Keyword(s):  
Neurodevelopmental Disorders ◽  
Neurodevelopmental Disorder ◽  
Molecular Genetic ◽  
Cortical Development ◽  
External Ear ◽  
Malformations Of Cortical Development ◽  
Phenotypic Spectrum ◽  
Whole Exome ◽  
Functional Consequences ◽  
Genetic Data Analysis

Neurodevelopmental disorder caused by malformations of cortical development is a rare neurological disease. Heterozygous missense variants in the TUBG1 gene lead to malformations of human cortical development, which further result in intellectual disability, developmental retardation, and epilepsy. To the best of our knowledge, only thirteen patients and a total of nine pathogenic TUBG1 variants have been described in the published literature. This study reports the case details and genetic data analysis of a girl (aged 8 years, 9 months) with developmental delay, psychomotor regression, epilepsy, and left external ear deformity. A novel TUBG1 mutation was identified by whole-exome sequencing and Sanger sequencing, confirming that this mutation may be the cause of the neurodevelopmental disorders. This case report characterizes the phenotypic spectrum, molecular genetic findings, and functional consequences of novel pathogenic TUBG1 variants in neurodevelopmental disorders caused by cortical development malformations.

scholarly journals Linking Autism Risk Genes to Disruption of Cortical Development

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2500
Author(s):  
Marta Garcia-Forn ◽  
Andrea Boitnott ◽  
Zeynep Akpinar ◽  
Silvia De Rubeis
Keyword(s):  
Large Scale ◽  
Association Studies ◽  
Neurodevelopmental Disorder ◽  
Cortical Development ◽  
Autism Spectrum ◽  
Repetitive Behaviors ◽  
Genome Wide Association Studies ◽  
Restricted Interests ◽  
Risk Genes ◽  
Whole Exome

Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder characterized by impairments in social communication and social interaction, and the presence of repetitive behaviors and/or restricted interests. In the past few years, large-scale whole-exome sequencing and genome-wide association studies have made enormous progress in our understanding of the genetic risk architecture of ASD. While showing a complex and heterogeneous landscape, these studies have led to the identification of genetic loci associated with ASD risk. The intersection of genetic and transcriptomic analyses have also begun to shed light on functional convergences between risk genes, with the mid-fetal development of the cerebral cortex emerging as a critical nexus for ASD. In this review, we provide a concise summary of the latest genetic discoveries on ASD. We then discuss the studies in postmortem tissues, stem cell models, and rodent models that implicate recently identified ASD risk genes in cortical development.

scholarly journals Early infantile epileptic-dyskinetic encephalopathy due to biallelic PIGP mutations

2020 ◽  
Vol 6 (1) ◽  
pp. e387 ◽  
Author(s):  
Annalisa Vetro ◽  
Tiziana Pisano ◽  
Silvia Chiaro ◽  
Elena Procopio ◽  
Azzurra Guerra ◽  
...  
Keyword(s):  
Neurodevelopmental Disorder ◽  
Brain Mri ◽  
Molecular Genetic ◽  
Genetic Diagnosis ◽  
Premature Death ◽  
Epileptic Encephalopathy ◽  
Whole Exome ◽  
Mri Scans ◽  
Severe Hypotonia ◽  
Profound Disability

ObjectiveTo describe clinical, biochemical, and molecular genetic findings in a large inbred family in which 4 children with a severe early-onset epileptic-dyskinetic encephalopathy, with suppression burst EEG, harbored homozygous mutations of phosphatidylinositol glycan anchor biosynthesis, class P (PIGP), a member of the large glycosylphosphatidylinositol (GPI) anchor biosynthesis gene family.MethodsWe studied clinical features, EEG, brain MRI scans, whole-exome sequencing (WES), and measured the expression of a subset of GPI-anchored proteins (GPI-APs) in circulating granulocytes using flow cytometry.ResultsThe 4 affected children exhibited a severe neurodevelopmental disorder featuring severe hypotonia with early dyskinesia progressing to quadriplegia, associated with infantile spasms, focal, tonic, and tonic-clonic seizures and a burst suppression EEG pattern. Two of the children died prematurely between age 2 and 12 years; the remaining 2 children are aged 2 years 7 months and 7 years 4 months. The homozygous c.384del variant of PIGP, present in the 4 patients, introduces a frame shift 6 codons before the expected stop signal and is predicted to result in the synthesis of a protein longer than the wild type, with impaired functionality. We demonstrated a reduced expression of the GPI-AP CD16 in the granulocytic membrane in affected individuals.ConclusionsPIGP mutations are consistently associated with an epileptic-dyskinetic encephalopathy with the features of early infantile epileptic encephalopathy with profound disability and premature death. CD16 is a valuable marker to support a genetic diagnosis of inherited GPI deficiencies.

scholarly journals Characterization of a KCNB1 variant associated with autism, intellectual disability, and epilepsy

2017 ◽  
Vol 3 (6) ◽  
pp. e198 ◽  
Author(s):  
Jeffrey D. Calhoun ◽  
Carlos G. Vanoye ◽  
Fernando Kok ◽  
Alfred L. George ◽  
Jennifer A. Kearney
Keyword(s):  
Protein Expression ◽  
Exome Sequencing ◽  
Biochemical Characterization ◽  
Neurodevelopmental Disorder ◽  
Functional Characterization ◽  
Loss Of Function ◽  
Phenotypic Spectrum ◽  
Whole Exome ◽  
Protein Dysfunction

Objective:To perform functional characterization of a potentially pathogenic KCNB1 variant identified by clinical exome sequencing of a proband with a neurodevelopmental disorder that included epilepsy and centrotemporal spikes on EEG.Methods:Whole-exome sequencing identified the KCNB1 variant c.595A>T (p.Ile199Phe). Biochemical and electrophysiologic experiments were performed to determine whether this variant affected protein expression, trafficking, and channel functional properties.Results:Biochemical characterization of the variant suggested normal protein expression and trafficking. Functional characterization revealed biophysical channel defects in assembled homotetrameric and heterotetrameric channels.Conclusions:The identification of the KCNB1 variant c.595A>T (p.Ile199Phe) in a neurodevelopmental disorder that included epilepsy with centrotemporal spikes expands the phenotypic spectrum of epilepsies associated with KCNB1 variants. The KCNB1-I199F variant exhibited partial loss of function relative to the wild-type channel. This defect is arguably less severe than previously reported KCNB1 variants, suggesting the possibility that the degree of KCNB1 protein dysfunction may influence disease severity.

scholarly journals Genetic subtypes, allelic effects, and convergent neurodevelopmental mechanisms

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Maitreya Das ◽  
Santhosh Girirajan
Keyword(s):  
Neurodevelopmental Disorders ◽  
High Throughput Sequencing ◽  
Complex Disease ◽  
Molecular Subtype ◽  
Neurodevelopmental Disorder ◽  
Disease Etiology ◽  
Risk Genes ◽  
Genetic Subtypes ◽  
Risk Variants ◽  
Functional Consequences

AbstractHigh-throughput sequencing of large affected cohorts have helped uncover a plethora of risk genes for complex neurodevelopmental disorders. However, untangling complex disease etiology also involves understanding the functional consequences of these mutations in order to connect risk variants to resulting phenotypes. Here, we highlight the efforts of Mannucci and colleagues to define a novel molecular subtype of neurodevelopmental disorder associated with mutations in DHX30 and characterize location-specific mutational effects in cell culture and zebrafish models.

scholarly journals Ultra-rare disruptive and damaging mutations influence educational attainment in the general population

2016 ◽  
Author(s):  
Andrea Ganna ◽  
Giulio Genovese ◽  
Daniel P. Howrigan ◽  
Andrea Byrnes ◽  
Mitja Kurki ◽  
...  
Keyword(s):  
General Population ◽  
Neurodevelopmental Disorders ◽  
Cognitive Abilities ◽  
Rare Variants ◽  
De Novo ◽  
Neurodevelopmental Disorder ◽  
P Value ◽  
Sequencing Data ◽  
Whole Exome ◽  
Number Variation

Ultra-rare inherited and de novo disruptive variants in highly constrained (HC) genes are enriched in neurodevelopmental disorders 1–5. However, their impact on cognition in the general population has not been explored. We hypothesize that disruptive and damaging ultra-rare variants (URVs) in HC genes not only confer risk to neurodevelopmental disorders, but also influence general cognitive abilities measured indirectly by years of education (YOE). We tested this hypothesis in 14,133 individuals with whole exome or genome sequencing data. The presence of one or more URVs was associated with a decrease in YOE (3.1 months less for each additional mutation; P-value=3.3×10−8) and the effect was stronger in HC genes enriched for brain expression (6.5 months less, P-value=3.4×10−5). The effect of these variants was more pronounced than the estimated effects of runs of homozygosity and pathogenic copy number variation 6–9. Our findings suggest that effects of URVs in HC genes are not confined to severe neurodevelopmental disorder, but influence the cognitive spectrum in the general population

scholarly journals Functional analysis of TLK2 variants and their proximal interactomes implicates impaired kinase activity and chromatin maintenance defects in their pathogenesis

2020 ◽  
pp. jmedgenet-2020-107281
Author(s):  
Lisa Pavinato ◽  
Marina Villamor-Payà ◽  
Maria Sanchiz-Calvo ◽  
Cristina Andreoli ◽  
Marina Gay ◽  
...  
Keyword(s):  
Neurodevelopmental Disorders ◽  
Kinase Activity ◽  
Neurodevelopmental Disorder ◽  
Missense Variant ◽  
Cell Cycle Checkpoint ◽  
Missense Change ◽  
Pathogenic Variants ◽  
Whole Exome ◽  
Related Phenotype ◽  
Cycle Checkpoint

IntroductionThe Tousled-like kinases 1 and 2 (TLK1 and TLK2) are involved in many fundamental processes, including DNA replication, cell cycle checkpoint recovery and chromatin remodelling. Mutations in TLK2 were recently associated with ‘Mental Retardation Autosomal Dominant 57’ (MRD57, MIM# 618050), a neurodevelopmental disorder characterised by a highly variable phenotype, including mild-to-moderate intellectual disability, behavioural abnormalities, facial dysmorphisms, microcephaly, epilepsy and skeletal anomalies.MethodsWe re-evaluate whole exome sequencing and array-CGH data from a large cohort of patients affected by neurodevelopmental disorders. Using spatial proteomics (BioID) and single-cell gel electrophoresis, we investigated the proximity interaction landscape of TLK2 and analysed the effects of p.(Asp551Gly) and a previously reported missense variant (c.1850C>T; p.(Ser617Leu)) on TLK2 interactions, localisation and activity.ResultsWe identified three new unrelated MRD57 families. Two were sporadic and caused by a missense change (c.1652A>G; p.(Asp551Gly)) or a 39 kb deletion encompassing TLK2, and one was familial with three affected siblings who inherited a nonsense change from an affected mother (c.1423G>T; p.(Glu475Ter)). The clinical phenotypes were consistent with those of previously reported cases. The tested mutations strongly impaired TLK2 kinase activity. Proximal interactions between TLK2 and other factors implicated in neurological disorders, including CHD7, CHD8, BRD4 and NACC1, were identified. Finally, we demonstrated a more relaxed chromatin state in lymphoblastoid cells harbouring the p.(Asp551Gly) variant compared with control cells, conferring susceptibility to DNA damage.ConclusionOur study identified novel TLK2 pathogenic variants, confirming and further expanding the MRD57-related phenotype. The molecular characterisation of missense variants increases our knowledge about TLK2 function and provides new insights into its role in neurodevelopmental disorders.

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