The Variable Expression of a Novel MBD5 Gene Frameshift Mutation in an Italian Family

2020 ◽  
Author(s):  
Alfredo Orrico ◽  
Lucia Galli ◽  
Maja Rossi ◽  
Ambra Cortesi ◽  
Marta Mazzi ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Novel Mutation ◽  
Point Mutations ◽  
Autism Spectrum ◽  
Cognitive Disability ◽  
Dominant Type ◽  
Variable Expression ◽  
Large Deletions ◽  
Pathogenic Variants ◽  
Autosomal Dominant Type

AbstractHaploinsufficiency of the methyl-CpG-binding domain protein 5 (MBD5) gene is reported as a cause of an autosomal dominant type of cognitive disability (MRD1) and autism spectrum disorder through large deletions involving multiple genes or point mutations, ultimately leading to haploinsufficiency in both cases. However, relatively few reports have been published on the phenotypical spectrum resulting from point mutations.We report here on a novel heterozygous frameshift variant in the MBD5 gene [c.2579del; p.(Lys860Argfs*11)] in a family in which the typical signs associated with pathogenic variants were expressed with different degrees of severity in the clinical presentation of the carrier individuals.Our findings, adding a novel mutation to the mutational spectrum, further support the relevance of the MBD5 gene as one of the main molecular mechanisms involved in the pathogenesis of intellectual disability and contribute to the characterization of the genotype–phenotype correlations.

Rubinstein–Taybi syndrome: clinical and molecular overview

2007 ◽  
Vol 9 (23) ◽  
pp. 1-16 ◽  
Author(s):  
Jeroen H. Roelfsema ◽  
Dorien J.M. Peters
Keyword(s):  
Mental Retardation ◽  
Growth Retardation ◽  
Molecular Mechanisms ◽  
Clinical Presentation ◽  
Point Mutations ◽  
Affected Individual ◽  
Histone Acetyltransferases ◽  
Signalling Pathways ◽  
Large Deletions ◽  
Strong Homology

Rubinstein–Taybi syndrome is characterised by mental retardation, growth retardation and a particular dysmorphology. The syndrome is rare, with a frequency of approximately one affected individual in 100 000 newborns. Mutations in two genes –CREBBPandEP300– have been identified to cause the syndrome. These two genes show strong homology and encode histone acetyltransferases (HATs), which are transcriptional co-activators involved in many signalling pathways. Loss of HAT activity is sufficient to account for the phenomena seen in Rubinstein–Taybi patients. Although some mutations found inCREBBPare translocations, inversions and large deletions, most are point mutations or small deletions and insertions. Mutations inEP300are comparatively rare. Extensive screening of patients has revealed mutations inCREBBPandEP300in around 50% of cases. The cause of the syndrome in the remaining patients remains to be identified, but other genes could also be involved. Here, we describe the clinical presentation of Rubinstein–Taybi syndrome, review the mutation spectrum and discuss the current understanding of causative molecular mechanisms.

scholarly journals Congenital Diseases of DNA Replication: Clinical Phenotypes and Molecular Mechanisms

2021 ◽  
Vol 22 (2) ◽  
pp. 911
Author(s):  
Megan Schmit ◽  
Anja-Katrin Bielinsky
Keyword(s):  
Dna Replication ◽  
Genomic Instability ◽  
Molecular Mechanisms ◽  
Point Mutations ◽  
Chromosomal Anomalies ◽  
Congenital Diseases ◽  
Clinical Phenotypes ◽  
Pathogenic Variants ◽  
Dna Alterations ◽  
Functional Mechanisms

Deoxyribonucleic acid (DNA) replication can be divided into three major steps: initiation, elongation and termination. Each time a human cell divides, these steps must be reiteratively carried out. Disruption of DNA replication can lead to genomic instability, with the accumulation of point mutations or larger chromosomal anomalies such as rearrangements. While cancer is the most common class of disease associated with genomic instability, several congenital diseases with dysfunctional DNA replication give rise to similar DNA alterations. In this review, we discuss all congenital diseases that arise from pathogenic variants in essential replication genes across the spectrum of aberrant replisome assembly, origin activation and DNA synthesis. For each of these conditions, we describe their clinical phenotypes as well as molecular studies aimed at determining the functional mechanisms of disease, including the assessment of genomic stability. By comparing and contrasting these diseases, we hope to illuminate how the disruption of DNA replication at distinct steps affects human health in a surprisingly cell-type-specific manner.

scholarly journals Causal variants in Maturity Onset Diabetes of the Young (MODY) – A systematic review

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ibrar Rafique ◽  
Asif Mir ◽  
Muhammad Arif Nadeem Saqib ◽  
Muhammad Naeem ◽  
Luc Marchand ◽  
...  
Keyword(s):  
Middle Eastern ◽  
Maturity Onset Diabetes ◽  
Dominant Type ◽  
Pathogenic Variants ◽  
Search Terms ◽  
Onset Diabetes ◽  
Causal Variants ◽  
Autosomal Dominant Type

Abstract Background Maturity Onset Diabetes of the Young (MODY) is an autosomal dominant type of diabetes. Pathogenic variants in fourteen genes are reported as causes of MODY. Its symptoms overlap with type 1 and type 2 diabetes. Reviews for clinical characteristics, diagnosis and treatments are available but a comprehensive list of genetic variants, is lacking. Therefore this study was designed to collect all the causal variants involved in MODY, reported to date. Methods We searched PubMed from its date of inception to December 2019. The search terms we used included disease names and name of all the known genes involved. The ClinVar database was also searched for causal variants in the known 14 MODY genes. Results The record revealed 1647 studies and among them, 326 studies were accessed for full-text. Finally, 239 studies were included, as per our inclusion criteria. A total of 1017 variants were identified through literature review and 74 unpublished variants from Clinvar database. The gene most commonly affected was GCK, followed by HNF1a. The traditional Sanger sequencing was used in 76 % of the cases and 65 % of the studies were conducted in last 10 years. Variants from countries like Jordan, Oman and Tunisia reported that the MODY types prevalent worldwide were not common in their countries. Conclusions We expect that this paper will help clinicians interpret MODY genetics results with greater confidence. Discrepancies in certain middle-eastern countries need to be investigated as other genes or factors, like consanguinity may be involved in developing diabetes.

scholarly journals Autosomal Dominant Type II Osteopctrosis in an Asymptomatic Adolescent: A Case Report

2009 ◽  
Vol 22 (2) ◽  
pp. 251-254
Author(s):  
MA Haque ◽  
LS Sharmin ◽  
I Mahmood ◽  
MH Rahman ◽  
D Huda
Keyword(s):  
Case Report ◽  
Bone Resorption ◽  
Autosomal Dominant ◽  
Heterogeneous Group ◽  
Type Ii ◽  
Dominant Type ◽  
Variable Expression ◽  
Variable Mode ◽  
Autosomal Dominant Type ◽  
Mode Of Inheritance

Osteopetrosis is a heterogeneous group of heritable conditions in which there is a defect in bone resorption by osteoclasts. The disease has variable mode of inheritance with variable expression of severity. We are reporting a 14 year old asymptomatic girl with autosomal dominant type II osteopetrosis and then the literature is reviewed.TAJ 2009; 22(1): 251-254

A Novel Mutation Glyl672→Arg in Type 2A and a Homozygous Mutation in Type 2B von Willebrand Disease

1996 ◽  
Vol 76 (02) ◽  
pp. 253-257 ◽  
Author(s):  
Takeshi Hagiwara ◽  
Hiroshi Inaba ◽  
Shinichi Yoshida ◽  
Keiko Nagaizumi ◽  
Morio Arai ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Novel Mutation ◽  
Point Mutations ◽  
Japanese Patients ◽  
Von Willebrand Disease ◽  
Homozygous Mutation ◽  
Missense Mutations ◽  
Reaction Products ◽  
Type 3 ◽  
Von Willebrand

SummaryGenetic materials from 16 unrelated Japanese patients with von Willebrand disease (vWD) were analyzed for mutations. Exon 28 of the von Willebrand factor (vWF) gene, where point mutations have been found most frequent, was screened by various restriction-enzyme analyses. Six patients were observed to have abnormal restriction patterns. By sequence analyses of the polymerase chain-reaction products, we identified a homozygous R1308C missense mutation in a patient with type 2B vWD; R1597W, R1597Q, G1609R and G1672R missense mutations in five patients with type 2A; and a G1659ter nonsense mutation in a patient with type 3 vWD. The G1672R was a novel missense mutation of the carboxyl-terminal end of the A2 domain. In addition, we detected an A/C polymorphism at nucleotide 4915 with HaeIII. There was no particular linkage disequilibrium of the A/C polymorphism, either with the G/A polymorphism at nucleotide 4391 detected with Hphl or with the C/T at 4891 detected with BstEll.

scholarly journals The Phosphatidylserine Receptor TIM-1 Enhances Authentic Chikungunya Virus Cell Entry

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1828
Author(s):  
Jared Kirui ◽  
Yara Abidine ◽  
Annasara Lenman ◽  
Koushikul Islam ◽  
Yong-Dae Gwon ◽  
...  
Keyword(s):  
Chikungunya Virus ◽  
Molecular Mechanisms ◽  
Rna Virus ◽  
Ectopic Expression ◽  
Point Mutations ◽  
Cell Entry ◽  
Target Cells ◽  
Human Hepatoma Cells ◽  
Chikv Infection ◽  
Phosphatidylserine Receptor

Chikungunya virus (CHIKV) is a re-emerging, mosquito-transmitted, enveloped positive stranded RNA virus. Chikungunya fever is characterized by acute and chronic debilitating arthritis. Although multiple host factors have been shown to enhance CHIKV infection, the molecular mechanisms of cell entry and entry factors remain poorly understood. The phosphatidylserine-dependent receptors, T-cell immunoglobulin and mucin domain 1 (TIM-1) and Axl receptor tyrosine kinase (Axl), are transmembrane proteins that can serve as entry factors for enveloped viruses. Previous studies used pseudoviruses to delineate the role of TIM-1 and Axl in CHIKV entry. Conversely, here, we use the authentic CHIKV and cells ectopically expressing TIM-1 or Axl and demonstrate a role for TIM-1 in CHIKV infection. To further characterize TIM-1-dependent CHIKV infection, we generated cells expressing domain mutants of TIM-1. We show that point mutations in the phosphatidylserine binding site of TIM-1 lead to reduced binding, entry, and infection of CHIKV. Ectopic expression of TIM-1 renders immortalized keratinocytes permissive to CHIKV, whereas silencing of endogenously expressed TIM-1 in human hepatoma cells reduces CHIKV infection. Altogether, our findings indicate that, unlike Axl, TIM-1 readily promotes the productive entry of authentic CHIKV into target cells.

scholarly journals Genetics and Epigenetics of One-Carbon Metabolism Pathway in Autism Spectrum Disorder: A Sex-Specific Brain Epigenome?

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 782
Author(s):  
Veronica Tisato ◽  
Juliana A. Silva ◽  
Giovanna Longo ◽  
Ines Gallo ◽  
Ajay V. Singh ◽  
...  
Keyword(s):  
Autism Spectrum Disorder ◽  
Molecular Mechanisms ◽  
Autism Spectrum ◽  
Mthfr Gene ◽  
Spectrum Disorder ◽  
Fetal Life ◽  
Clinical Phenotypes ◽  
One Carbon Metabolism ◽  
Causes And Risk Factors ◽  
Individual Disease

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition affecting behavior and communication, presenting with extremely different clinical phenotypes and features. ASD etiology is composite and multifaceted with several causes and risk factors responsible for different individual disease pathophysiological processes and clinical phenotypes. From a genetic and epigenetic side, several candidate genes have been reported as potentially linked to ASD, which can be detected in about 10–25% of patients. Folate gene polymorphisms have been previously associated with other psychiatric and neurodegenerative diseases, mainly focused on gene variants in the DHFR gene (5q14.1; rs70991108, 19bp ins/del), MTHFR gene (1p36.22; rs1801133, C677T and rs1801131, A1298C), and CBS gene (21q22.3; rs876657421, 844ins68). Of note, their roles have been scarcely investigated from a sex/gender viewpoint, though ASD is characterized by a strong sex gap in onset-risk and progression. The aim of the present review is to point out the molecular mechanisms related to intracellular folate recycling affecting in turn remethylation and transsulfuration pathways having potential effects on ASD. Brain epigenome during fetal life necessarily reflects the sex-dependent different imprint of the genome-environment interactions which effects are difficult to decrypt. We here will focus on the DHFR, MTHFR and CBS gene-triad by dissecting their roles in a sex-oriented view, primarily to bring new perspectives in ASD epigenetics.

scholarly journals Neurodevelopmental Trajectories and Psychiatric Morbidity: Lessons Learned From the 22q11.2 Deletion Syndrome

2021 ◽  
Vol 23 (3) ◽  
Author(s):  
Ania M. Fiksinski ◽  
Maude Schneider ◽  
Janneke Zinkstok ◽  
Danielle Baribeau ◽  
Samuel J. R. A. Chawner ◽  
...  
Keyword(s):  
Genetic Variants ◽  
Clinical Care ◽  
Psychiatric Morbidity ◽  
Phenotypic Expression ◽  
22Q11.2 Deletion Syndrome ◽  
Autism Spectrum ◽  
Lessons Learned ◽  
Deletion Syndrome ◽  
22Q11.2 Deletion ◽  
Variable Expression

AbstractPurpose of ReviewThe 22q11.2 deletion syndrome (22q11DS) is associated with a broad spectrum of neurodevelopmental phenotypes and is the strongest known single genetic risk factor for schizophrenia. Compared to other rare structural pathogenic genetic variants, 22q11DS is relatively common and one of the most extensively studied. This review provides a state-of-the-art overview of current insights regarding associated neurodevelopmental phenotypes and potential implications for 22q11DS and beyond.Recent FindingsWe will first discuss recent findings with respect to neurodevelopmental phenotypic expression associated with 22q11DS, including psychotic disorders, intellectual functioning, autism spectrum disorders, as well as their interactions. Second, we will address considerations that are important in interpreting these data and propose potential implications for both the clinical care for and the empirical study of individuals with 22q11DS. Third, we will highlight variable penetrance and pleiotropy with respect to neurodevelopmental phenotypes in 22q11DS. We will discuss how these phenomena are consistently observed in the context of virtually all rare pathogenic variants and that they pose substantial challenges from both a clinical and a research perspective.SummaryWe outline how 22q11DS could be viewed as a genetic model for studying neurodevelopmental phenotypes. In addition, we propose that 22q11DS research can help elucidate mechanisms underlying variable expression and pleiotropy of neurodevelopmental phenotypes, insights that are likely relevant for 22q11DS and beyond, including for individuals with other rare pathogenic genetic variants and for individuals with idiopathic neurodevelopmental conditions.

scholarly journals Loss of histone methyltransferase ASH1L in the developing mouse brain causes autistic-like behaviors

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yuen Gao ◽  
Natalia Duque-Wilckens ◽  
Mohammad B. Aljazi ◽  
Yan Wu ◽  
Adam J. Moeser ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mouse Brain ◽  
Molecular Mechanisms ◽  
Gene Mutations ◽  
Autism Spectrum ◽  
Normal Brain ◽  
Critical Function ◽  
Developmental Defects ◽  
Neurodevelopmental Disease ◽  
Developing Mouse Brain

AbstractAutism spectrum disorder (ASD) is a neurodevelopmental disease associated with various gene mutations. Recent genetic and clinical studies report that mutations of the epigenetic gene ASH1L are highly associated with human ASD and intellectual disability (ID). However, the causality and underlying molecular mechanisms linking ASH1L mutations to genesis of ASD/ID remain undetermined. Here we show loss of ASH1L in the developing mouse brain is sufficient to cause multiple developmental defects, core autistic-like behaviors, and impaired cognitive memory. Gene expression analyses uncover critical roles of ASH1L in regulating gene expression during neural cell development. Thus, our study establishes an ASD/ID mouse model revealing the critical function of an epigenetic factor ASH1L in normal brain development, a causality between Ash1L mutations and ASD/ID-like behaviors in mice, and potential molecular mechanisms linking Ash1L mutations to brain functional abnormalities.

scholarly journals mCSM-membrane: predicting the effects of mutations on transmembrane proteins

2020 ◽  
Vol 48 (W1) ◽  
pp. W147-W153 ◽  
Author(s):  
Douglas E V Pires ◽  
Carlos H M Rodrigues ◽  
David B Ascher
Keyword(s):  
Membrane Proteins ◽  
Single Point ◽  
Point Mutations ◽  
Web Server ◽  
Protein Coding ◽  
Pathogenic Variants ◽  
Model Protein ◽  
Matthew’S Correlation Coefficient ◽  
Membrane Protein Stability ◽  
User Friendly

Abstract Significant efforts have been invested into understanding and predicting the molecular consequences of mutations in protein coding regions, however nearly all approaches have been developed using globular, soluble proteins. These methods have been shown to poorly translate to studying the effects of mutations in membrane proteins. To fill this gap, here we report, mCSM-membrane, a user-friendly web server that can be used to analyse the impacts of mutations on membrane protein stability and the likelihood of them being disease associated. mCSM-membrane derives from our well-established mutation modelling approach that uses graph-based signatures to model protein geometry and physicochemical properties for supervised learning. Our stability predictor achieved correlations of up to 0.72 and 0.67 (on cross validation and blind tests, respectively), while our pathogenicity predictor achieved a Matthew's Correlation Coefficient (MCC) of up to 0.77 and 0.73, outperforming previously described methods in both predicting changes in stability and in identifying pathogenic variants. mCSM-membrane will be an invaluable and dedicated resource for investigating the effects of single-point mutations on membrane proteins through a freely available, user friendly web server at http://biosig.unimelb.edu.au/mcsm_membrane.

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