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Genetic Basis of Sensory and Neurological Disorders

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A special issue of Genes (ISSN 2073-4425). This special issue belongs to the section "Human Genomics and Genetic Diseases".

Deadline for manuscript submissions: closed (15 December 2021) | Viewed by 39346

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Special Issue Editor

Dr. Isabelle Schrauwen

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Guest Editor

Center for Statistical Genetics, Sergievsky Center, Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
Interests: genetics; neurodevelopmental disorders; neurological disorders; hearing loss; sensory disorders; rare pediatric diseases

Special Issue Information

Dear Colleagues,

Over the past decade, exome sequencing has emerged as a cost-effective way of identifying pathogenic variants involved in various neurological and sensory disorders. The nervous system, including the sensory nervous system, is a highly complex network in humans linked to a large number of hereditary disorders. Although exome sequencing has led to a tremendous increase in knowledge, a large fraction of the genetic etiology of these disorders remains to be identified. The identification of novel variants and genes remains important to improve our knowledge on the underlying genetic architecture, patient counseling, and management. In addition, novel innovative methods are now available that will improve variant identification, including the integration of various “-omics” or novel sequencing techniques.

Submissions in this Special Issue should be focused on exploring the genetic architecture of neurological and/or sensory disorders. This issue will span diverse topics ranging from pediatric neurodevelopmental disorders to adult-onset disorders affecting the nervous and/or sensory nervous systems.

Dr. Isabelle Schrauwen
Guest Editor

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Keywords

Neurological disorders
Neurodevelopmental disorders
Sensory disorders
Gene identification
Next-generation sequencing
DNA sequencing
RNA sequencing
Methylation profiling
Omics
Long-read sequencing

Published Papers (14 papers)

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16 pages, 2987 KiB

Open AccessArticle

CLN8 Gene Compound Heterozygous Variants: A New Case and Protein Bioinformatics Analyses

by Rajech Sharkia, Abdelnaser Zalan, Hazar Zahalka, Amit Kessel, Ayman Asaly, Wasif Al-Shareef and Muhammad Mahajnah

Genes 2022, 13(8), 1393; https://0-doi-org.brum.beds.ac.uk/10.3390/genes13081393 - 05 Aug 2022

Cited by 1 | Viewed by 1601

Abstract

The CLN8 disease type refers to one of the neuronal ceroid lipofuscinoses (NCLs) which are the most common group of neurodegenerative diseases in childhood. The clinical phenotypes of this disease are progressive neurological deterioration that could lead to seizures, dementia, ataxia, visual failure, and various forms of abnormal movement. In the current study, we describe two patients who presented with atypical phenotypic manifestation and protracted clinical course of CLN8 carrying a novel compound heterozygous variant at the CLN8 gene. Our patients developed a mild phenotype of CLN8 disease: as they presented mild epilepsy, cognitive decline, mild learning disability, attention-deficit/hyperactivity disorder (ADHD), they developed a markedly protracted course of motor decline. Bioinformatic analyses of the compound heterozygous CLN8 gene variants were carried out. Most of the variants seem likely to act by compromising the structural integrity of regions within the protein. This in turn is expected to reduce the overall stability of the protein and render the protein less active to various degrees. The cases in our study confirmed and expanded the effect of compound heterozygous variants in CLN8 disease. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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12 pages, 1738 KiB

Open AccessArticle

Disrupted Mitochondrial Network Drives Deficits of Learning and Memory in a Mouse Model of FOXP1 Haploinsufficiency

by Jing Wang, Gudrun A. Rappold and Henning Fröhlich

Genes 2022, 13(1), 127; https://0-doi-org.brum.beds.ac.uk/10.3390/genes13010127 - 11 Jan 2022

Cited by 2 | Viewed by 3367

Abstract

Reduced cognitive flexibility, characterized by restricted interests and repetitive behavior, is associated with atypical memory performance in autism spectrum disorder (ASD), suggesting hippocampal dysfunction. FOXP1 syndrome is a neurodevelopmental disorder characterized by ASD, language deficits, global developmental delay, and mild to moderate intellectual disability. Strongly reduced Foxp1 expression has been detected in the hippocampus of Foxp1^+/− mice, a brain region required for learning and memory. To investigate learning and memory performance in these animals, fear conditioning tests were carried out, which showed impaired associative learning compared with wild type (WT) animals. To shed light on the underlying mechanism, we analyzed various components of the mitochondrial network in the hippocampus. Several proteins regulating mitochondrial biogenesis (e.g., Foxo1, Pgc-1α, Tfam) and dynamics (Mfn1, Opa1, Drp1 and Fis1) were significantly dysregulated, which may explain the increased mitophagy observed in the Foxp1^+/− hippocampus. The reduced activity of complex I and decreased expression of Sod2 most likely increase the production of reactive oxygen species and the expression of the pre-apoptotic proteins Bcl-2 and Bax in this tissue. In conclusion, we provide evidence that a disrupted mitochondrial network and the resulting oxidative stress in the hippocampus contribute to the altered learning and cognitive impairment in Foxp1^+/− mice, suggesting that similar alterations also play a major role in patients with FOXP1 syndrome. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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17 pages, 1031 KiB

Open AccessArticle

Exome Sequencing Reveals Novel Variants and Expands the Genetic Landscape for Congenital Microcephaly

by Mateusz Dawidziuk, Tomasz Gambin, Ewelina Bukowska-Olech, Dorota Antczak-Marach, Magdalena Badura-Stronka, Piotr Buda, Edyta Budzynska, Jennifer Castaneda, Tatiana Chilarska, Elzbieta Czyzyk, Anna Eckersdorf-Mastalerz, Jolanta Fijak-Moskal, Dorota Gieruszczak-Bialek, Ewelina Glodek-Brzozowska, Alicja Goszczanska-Ciuchta, Malgorzata Grzeszykowska-Podymniak, Barbara Gurda, Anna Jakubiuk-Tomaszuk, Ewa Jamroz, Magdalena Janeczko, Dominika Jedlińska-Pijanowska, Marta Jurek, Dagmara Karolewska, Adela Kazmierczak, Teresa Kleist, Iwona Kochanowska, Malgorzata Krajewska-Walasek, Katarzyna Kufel, Anna Kutkowska-Kaźmierczak, Agata Lipiec, Dorota Maksym-Gasiorek, Anna Materna-Kiryluk, Hanna Mazurkiewicz, Michał Milewski, Tatsiana Pavina-Guglas, Aleksandra Pietrzyk, Renata Posmyk, Antoni Pyrkosz, Mariola Rudzka-Dybala, Ryszard Slezak, Marzena Wisniewska, Zofia Zalewska-Miszkurka, Elzbieta Szczepanik, Ewa Obersztyn, Monika Bekiesinska-Figatowska, Pawel Gawlinski and Wojciech Wiszniewski Show full author list Hide full author list

Genes 2021, 12(12), 2014; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12122014 - 18 Dec 2021

Cited by 7 | Viewed by 3432

Abstract

Congenital microcephaly causes smaller than average head circumference relative to age, sex and ethnicity and is most usually associated with a variety of neurodevelopmental disorders. The underlying etiology is highly heterogeneous and can be either environmental or genetic. Disruption of any one of multiple biological processes, such as those underlying neurogenesis, cell cycle and division, DNA repair or transcription regulation, can result in microcephaly. This etiological heterogeneity manifests in a clinical variability and presents a major diagnostic and therapeutic challenge, leaving an unacceptably large proportion of over half of microcephaly patients without molecular diagnosis. To elucidate the clinical and genetic landscapes of congenital microcephaly, we sequenced the exomes of 191 clinically diagnosed patients with microcephaly as one of the features. We established a molecular basis for microcephaly in 71 patients (37%), and detected novel variants in five high confidence candidate genes previously unassociated with this condition. We report a large number of patients with mutations in tubulin-related genes in our cohort as well as higher incidence of pathogenic mutations in MCPH genes. Our study expands the phenotypic and genetic landscape of microcephaly, facilitating differential clinical diagnoses for disorders associated with most commonly disrupted genes in our cohort. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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15 pages, 8679 KiB

Open AccessArticle

A Monoallelic Variant in REST Is Associated with Non-Syndromic Autosomal Dominant Hearing Impairment in a South African Family

by Noluthando Manyisa, Isabelle Schrauwen, Leonardo Alves de Souza Rios, Shaheen Mowla, Cedrik Tekendo-Ngongang, Kalinka Popel, Kevin Esoh, Thashi Bharadwaj, Liz M. Nouel-Saied, Anushree Acharya, Abdul Nasir, Edmond Wonkam-Tingang, Carmen de Kock, Collet Dandara, Suzanne M. Leal and Ambroise Wonkam

Genes 2021, 12(11), 1765; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12111765 - 06 Nov 2021

Cited by 4 | Viewed by 2267

Abstract

Hearing impairment (HI) is a sensory disorder with a prevalence of 0.0055 live births in South Africa. DNA samples from a South African family presenting with progressive, autosomal dominant non-syndromic HI were subjected to whole-exome sequencing, and a novel monoallelic variant in REST [c.1244GC; p.(C415S)], was identified as the putative causative variant. The co-segregation of the variant was confirmed with Sanger Sequencing. The variant is absent from databases, 103 healthy South African controls, and 52 South African probands with isolated HI. In silico analysis indicates that the p.C415S variant in REST substitutes a conserved cysteine and results in changes to the surrounding secondary structure and the disulphide bonds, culminating in alteration of the tertiary structure of REST. Localization studies using ectopically expressed GFP-tagged Wild type (WT) and mutant REST in HEK-293 cells show that WT REST localizes exclusively to the nucleus; however, the mutant protein localizes throughout the cell. Additionally, mutant REST has an impaired ability to repress its known target AF1q. The data demonstrates that the identified mutation compromises the function of REST and support its implication in HI. This study is the second report, worldwide, to implicate REST in HI and suggests that it should be included in diagnostic HI panels. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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24 pages, 2353 KiB

Open AccessArticle

Alternative Splicing Mechanisms Underlying Opioid-Induced Hyperalgesia

by Pan Zhang, Olivia C. Perez, Bruce R. Southey, Jonathan V. Sweedler, Amynah A. Pradhan and Sandra L. Rodriguez-Zas

Genes 2021, 12(10), 1570; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12101570 - 01 Oct 2021

Cited by 5 | Viewed by 2649

Abstract

Prolonged use of opioids can cause opioid-induced hyperalgesia (OIH). The impact of alternative splicing on OIH remains partially characterized. A study of the absolute and relative modes of action of alternative splicing further the understanding of the molecular mechanisms underlying OIH. Differential absolute and relative isoform profiles were detected in the trigeminal ganglia and nucleus accumbens of mice presenting OIH behaviors elicited by chronic morphine administration relative to control mice. Genes that participate in glutamatergic synapse (e.g., Grip1, Grin1, Wnk3), myelin protein processes (e.g., Mbp, Mpz), and axon guidance presented absolute and relative splicing associated with OIH. Splicing of genes in the gonadotropin-releasing hormone receptor pathway was detected in the nucleus accumbens while splicing in the vascular endothelial growth factor, endogenous cannabinoid signaling, circadian clock system, and metabotropic glutamate receptor pathways was detected in the trigeminal ganglia. A notable finding was the prevalence of alternatively spliced transcription factors and regulators (e.g., Ciart, Ablim2, Pbx1, Arntl2) in the trigeminal ganglia. Insights into the nociceptive and antinociceptive modulatory action of Hnrnpk were gained. The results from our study highlight the impact of alternative splicing and transcriptional regulators on OIH and expose the need for isoform-level research to advance the understanding of morphine-associated hyperalgesia. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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14 pages, 1525 KiB

Open AccessArticle

A New Pathogenic Variant in POU3F4 Causing Deafness Due to an Incomplete Partition of the Cochlea Paved the Way for Innovative Surgery

by Ahmet M. Tekin, Marco Matulic, Wim Wuyts, Masoud Zoka Assadi, Griet Mertens, Vincent van Rompaey, Yongxin Li, Paul van de Heyning and Vedat Topsakal

Genes 2021, 12(5), 613; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12050613 - 21 Apr 2021

Cited by 13 | Viewed by 3307

Abstract

Incomplete partition type III (IP-III) is a relatively rare inner ear malformation that has been associated with a POU3F4 gene mutation. The IP-III anomaly is mainly characterized by incomplete separation of the modiolus of the cochlea from the internal auditory canal. We describe a 71-year-old woman with profound sensorineural hearing loss diagnosed with an IP-III of the cochlea that underwent cochlear implantation. Via targeted sequencing with a non-syndromic gene panel, we identified a heterozygous c.934G > C p. (Ala31Pro) pathogenic variant in the POU3F4 gene that has not been reported previously. IP-III of the cochlea is challenging for cochlear implant surgery for two main reasons: liquor cerebrospinalis gusher and electrode misplacement. Surgically, it may be better to opt for a shorter array because it is less likely for misplacement with the electrode in a false route. Secondly, the surgeon has to consider the insertion angles of cochlear access very strictly to avoid misplacement along the inner ear canal. Genetic results in well describes genotype-phenotype correlations are a strong clinical tool and as in this case guided surgical planning and robotic execution. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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16 pages, 628 KiB

Open AccessArticle

Identification of Novel Candidate Genes and Variants for Hearing Loss and Temporal Bone Anomalies

by Regie Lyn P. Santos-Cortez, Talitha Karisse L. Yarza, Tori C. Bootpetch, Ma. Leah C. Tantoco, Karen L. Mohlke, Teresa Luisa G. Cruz, Mary Ellen Chiong Perez, Abner L. Chan, Nanette R. Lee, Celina Ann M. Tobias-Grasso, Maria Rina T. Reyes-Quintos, Eva Maria Cutiongco-de la Paz and Charlotte M. Chiong

Genes 2021, 12(4), 566; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12040566 - 13 Apr 2021

Cited by 7 | Viewed by 2964

Abstract

Background: Hearing loss remains an important global health problem that is potentially addressed through early identification of a genetic etiology, which helps to predict outcomes of hearing rehabilitation such as cochlear implantation and also to mitigate the long-term effects of comorbidities. The identification of variants for hearing loss and detailed descriptions of clinical phenotypes in patients from various populations are needed to improve the utility of clinical genetic screening for hearing loss. Methods: Clinical and exome data from 15 children with hearing loss were reviewed. Standard tools for annotating variants were used and rare, putatively deleterious variants were selected from the exome data. Results: In 15 children, 21 rare damaging variants in 17 genes were identified, including: 14 known hearing loss or neurodevelopmental genes, 11 of which had novel variants; and three candidate genes IST1, CBLN3 and GDPD5, two of which were identified in children with both hearing loss and enlarged vestibular aqueducts. Patients with variants within IST1 and MYO18B had poorer outcomes after cochlear implantation. Conclusion: Our findings highlight the importance of identifying novel variants and genes in ethnic groups that are understudied for hearing loss. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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8 pages, 2723 KiB

Open AccessArticle

Novel GRHL2 Gene Variant Associated with Hearing Loss: A Case Report and Review of the Literature

by Katarina Trebusak Podkrajsek, Tine Tesovnik, Nina Bozanic Urbancic and Saba Battelino

Genes 2021, 12(4), 484; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12040484 - 26 Mar 2021

Cited by 5 | Viewed by 1776

Abstract

In contrast to the recessive form, hearing loss inherited in a dominant manner is more often post-lingual and typically results in a progressive sensorineural hearing loss with variable severity and late onset. Variants in the GRHL2 gene are an extremely rare cause of dominantly inherited hearing loss. Genetic testing is a crucial part of the identification of the etiology of hearing loss in individual patients, especially when performed with next-generation sequencing, enabling simultaneous analysis of numerous genes, including those rarely associated with hearing loss. We aimed to evaluate the genetic etiology of hearing loss in a family with moderate late-onset hearing loss using next-generation sequencing and to conduct a review of reported variants in the GRHL2 gene. We identified a novel disease-causing variant in the GRHL2 gene (NM_024915: c.1510C>T; p.Arg504Ter) in both affected members of the family. They both presented with moderate late-onset hearing loss with no additional clinical characteristics. Reviewing known GRHL2 variants associated with hearing loss, we can conclude that they are more likely to be truncating variants, while the associated onset of hearing loss is variable. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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13 pages, 971 KiB

Open AccessEditor’s ChoiceReview

Clinical and Genetic Aspects of Phelan–McDermid Syndrome: An Interdisciplinary Approach to Management

by Francisco Cammarata-Scalisi, Michele Callea, Diego Martinelli, Colin Eric Willoughby, Antonio Cárdenas Tadich, Maykol Araya Castillo, María Angelina Lacruz-Rengel, Marco Medina, Piercesare Grimaldi, Enrico Bertini and Julián Nevado

Genes 2022, 13(3), 504; https://0-doi-org.brum.beds.ac.uk/10.3390/genes13030504 - 12 Mar 2022

Cited by 8 | Viewed by 3539

Abstract

Phelan–McDermid syndrome (PMS) is a rare, heterogeneous, and complex neurodevelopmental disorder. It is generally caused by a heterozygous microdeletion of contiguous genes located in the distal portion of the long arm of chromosome 22, including the SHANK3 gene. Sequence variants of SHANK3, including frameshift, nonsense mutations, small indels and splice site mutations also result in PMS. Furthermore, haploinsufficiency in SHANK3 has been suggested as the main cause of PMS. SHANK3 is also associated with intellectual disability, autism spectrum disorder and schizophrenia. The phenotype of PMS is variable, and lacks a distinctive phenotypic characteristic, so the clinical diagnosis should be confirmed by genetic analysis. PMS is a multi-system disorder, and clinical care must encompass various specialties and therapists. The role of risperidone, intranasal insulin, insulin growth factor 1, and oxytocin as potential therapeutic options in PMS will be discussed in this review. The diagnosis of PMS is important to provide an appropriate clinical evaluation, treatment, and genetic counseling. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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24 pages, 1949 KiB

Open AccessReview

Methods to Improve Molecular Diagnosis in Genomic Cold Cases in Pediatric Neurology

by Magda K. Kadlubowska and Isabelle Schrauwen

Genes 2022, 13(2), 333; https://0-doi-org.brum.beds.ac.uk/10.3390/genes13020333 - 11 Feb 2022

Cited by 3 | Viewed by 3813

Abstract

During the last decade, genetic testing has emerged as an important etiological diagnostic tool for Mendelian diseases, including pediatric neurological conditions. A genetic diagnosis has a considerable impact on disease management and treatment; however, many cases remain undiagnosed after applying standard diagnostic sequencing techniques. This review discusses various methods to improve the molecular diagnostic rates in these genomic cold cases. We discuss extended analysis methods to consider, non-Mendelian inheritance models, mosaicism, dual/multiple diagnoses, periodic re-analysis, artificial intelligence tools, and deep phenotyping, in addition to integrating various omics methods to improve variant prioritization. Last, novel genomic technologies, including long-read sequencing, artificial long-read sequencing, and optical genome mapping are discussed. In conclusion, a more comprehensive molecular analysis and a timely re-analysis of unsolved cases are imperative to improve diagnostic rates. In addition, our current understanding of the human genome is still limited due to restrictions in technologies. Novel technologies are now available that improve upon some of these limitations and can capture all human genomic variation more accurately. Last, we recommend a more routine implementation of high molecular weight DNA extraction methods that is coherent with the ability to use and/or optimally benefit from these novel genomic methods. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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8 pages, 1214 KiB

Open AccessCase Report

Phenotype Expansion for Atypical Gaucher Disease Due to Homozygous Missense PSAP Variant in a Large Consanguineous Pakistani Family

by Khurram Liaqat, Shabir Hussain, Anushree Acharya, Abdul Nasir, Thashi Bharadwaj, Muhammad Ansar, Sulman Basit, Isabelle Schrauwen, Wasim Ahmad and Suzanne M. Leal

Genes 2022, 13(4), 662; https://0-doi-org.brum.beds.ac.uk/10.3390/genes13040662 - 09 Apr 2022

Cited by 3 | Viewed by 2157

Abstract

Atypical Gaucher disease is caused by variants in the PSAP gene. Saposin C is one of four homologous proteins derived from sequential cleavage of the saposin precursor protein, prosaposin. It is an essential activator for glucocerebrosidase, which is deficient in Gaucher disease. Although atypical Gaucher disease due to deficiency of saposin C is rare, it exhibits vast phenotypic heterogeneity. Here, we report on a Pakistani family that exhibits features of Gaucher disease, i.e., prelingual profound sensorineural hearing impairment, vestibular dysfunction, hepatosplenomegaly, kyphosis, and thrombocytopenia. The family was investigated using exome and Sanger sequencing. A homozygous missense variant c.1076A>C: p.(Glu359Ala) in exon 10 of the PSAP gene was observed in all affected family members. In conclusion, we identified a new likely pathogenic missense variant in PSAP in a large consanguineous Pakistani family with atypical Gaucher disease. Gaucher disease due to a deficiency of saposin C has not been previously reported within the Pakistani population. Genetic screening of patients with the aforementioned phenotypes could ensure adequate follow-up and the prevention of further complications. Our finding expands the genetic and phenotypic spectrum of atypical Gaucher disease due to a saposin C deficiency. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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7 pages, 1263 KiB

Open AccessCase Report

NGS-Based Diagnosis of Treatable Neurogenetic Disorders in Adults: Opportunities and Challenges

by Jean-Marc Good, Isis Atallah, Mayte Castro Jimenez, David Benninger, Thierry Kuntzer, Andrea Superti-Furga and Christel Tran

Genes 2021, 12(5), 695; https://0-doi-org.brum.beds.ac.uk/10.3390/genes12050695 - 06 May 2021

Cited by 5 | Viewed by 2282

Abstract

The identification of neurological disorders by next-generation sequencing (NGS)-based gene panels has helped clinicians understand the underlying physiopathology, resulting in personalized treatment for some rare diseases. While the phenotype of distinct neurogenetic disorders is generally well-known in childhood, in adulthood, the phenotype can be unspecific and make the standard diagnostic approach more complex. Here we present three unrelated adults with various neurological manifestations who were successfully diagnosed using NGS, allowing for the initiation of potentially life-changing treatments. A 63-year-old woman with progressive cognitive decline, pyramidal signs, and bilateral cataract was treated by chenodeoxycholic acid following the diagnosis of cerebrotendinous xanthomatosis due to a homozygous variant in CYP27A1. A 32-year-old man with adult-onset spastic paraplegia, in whom a variant in ABCD1 confirmed an X-linked adrenoleukodystrophy, was treated with corticoids for adrenal insufficiency. The third patient, a 28-year-old woman with early-onset developmental delay, epilepsy, and movement disorders was treated with a ketogenic diet following the identification of a variant in SLC2A1, confirming a glucose transporter type 1 deficiency syndrome. This case study illustrates the challenges in the timely diagnosis of medically actionable neurogenetic conditions, but also the considerable potential for improving patient health through modern sequencing technologies. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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8 pages, 1628 KiB

Open AccessCase Report

The First Case of Congenital Myasthenic Syndrome Caused by a Large Homozygous Deletion in the C-Terminal Region of COLQ (Collagen Like Tail Subunit of Asymmetric Acetylcholinesterase) Protein

by Nicola Laforgia, Lucrezia De Cosmo, Orazio Palumbo, Carlotta Ranieri, Michela Sesta, Donatella Capodiferro, Antonino Pantaleo, Pierluigi Iapicca, Patrizia Lastella, Manuela Capozza, Federico Schettini, Nenad Bukvic, Rosanna Bagnulo and Nicoletta Resta

Genes 2020, 11(12), 1519; https://0-doi-org.brum.beds.ac.uk/10.3390/genes11121519 - 18 Dec 2020

Cited by 8 | Viewed by 2439

Abstract

Congenital myasthenic syndromes (CMSs) are caused by mutations in genes that encode proteins involved in the organization, maintenance, function, or modification of the neuromuscular junction. Among these, the collagenic tail of endplate acetylcholinesterase protein (COLQ; MIM 603033) has a crucial role in anchoring the enzyme into the synaptic basal lamina. Here, we report on the first case of a patient with a homozygous deletion affecting the last exons of the COLQ gene in a CMS patient born to consanguineous parents of Pakistani origin. Electromyography (EMG), electroencephalography (EEG), clinical exome sequencing (CES), and single nucleotide polymorphism (SNP) array analyses were performed. The subject was born at term after an uneventful pregnancy and developed significant hypotonia and dystonia, clinical pseudoseizures, and recurring respiratory insufficiency with a need for mechanical ventilation. CES analysis of the patient revealed a homozygous deletion of the COLQ gene located on the 3p25.1 chromosome region. The SNP-array confirmed the presence of deletion that extended from exon 11 to the last exon 17 with a size of 19.5 Kb. Our results add new insights about the underlying pathogenetic mechanisms expanding the spectrum of causative COLQ mutations. It is relevant, considering the therapeutic implications, to apply suitable molecular approaches so that no type of mutation is missed: “each lost mutation means a baby treated improperly”. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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8 pages, 2954 KiB

Open AccessCase Report

Identification of a Novel de Novo Variant in the SYT2 Gene Causing a Rare Type of Distal Hereditary Motor Neuropathy

by Olga Mironovich, Elena Dadali, Sergey Malmberg, Tatyana Markova, Oxana Ryzhkova and Aleksander Poliakov

Genes 2020, 11(11), 1238; https://0-doi-org.brum.beds.ac.uk/10.3390/genes11111238 - 22 Oct 2020

Cited by 7 | Viewed by 2198

Abstract

Objective: To report the first de novo missense mutation in the SYT2 gene causing distal hereditary motor neuropathy. Methods: Genetic testing was carried out, including clinical exome sequencing for the proband and Sanger sequencing for the proband and his parents. We described the clinical and electrophysiological features found in the patient. Results: We reported a proband with a new de novo missense mutation, c.917C>T (p.Ser306Leu), in the C2B domain of SYT2. The clinical presentation was similar to that of phenotypes described in previous studies. A notable feature in our study was normal electrophysiological testing results of the patient. Conclusions: In this study we reinforced the association between SYT2 mutations and distal hereditary motor neuropathy. We also described the clinical presentation of the patient carrying this pathogenic variant and provided unusual results of electrophysiological testing. The results showed that a diagnosis of SYT2-associated neuropathy should be based on the similarity of clinical manifestations, rather than the results of electrophysiological testing. Full article

(This article belongs to the Special Issue Genetic Basis of Sensory and Neurological Disorders)

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