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Batheja A, Bayer-Vile J, Silverstein E, Couser N. Congenital Myasthenic Syndrome associated with acetylcholine receptor deficiency: case report and review of the literature. Ophthalmic Genet 2024:1-7. [PMID: 38832364 DOI: 10.1080/13816810.2024.2352391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 05/02/2024] [Indexed: 06/05/2024]
Abstract
INTRODUCTION Congenital Myasthenic Syndromes are a diverse group of conditions with a broad array of genetic underpinnings and phenotypic presentations. Acetylcholine receptor deficiency is one form that usually involves pathogenic variants in the Cholinergic Receptor Nicotinic Epsilon Subunit (CHRNE) gene encoding the ɛ-subunit of the acetylcholine receptor. METHODS We report a case of a 4-year-old male with suspected Congenital Myasthenic Syndrome with Acetylcholine Receptor Deficiency who presented with ocular symptoms and generalized muscle weakness. We additionally summarize published findings regarding the genetic, phenotypic, and clinical considerations of Congenital Myasthenic Syndrome with Acetylcholine Receptor Deficiency. RESULTS Exome sequencing revealed biallelic variants in CHRNE gene with a pathogenic frameshift variant and a variant of uncertain significance. After suboptimal response to pyridostigmine and albuterol, the patient experienced benefit with 3,4-DAP. The most commonly reported clinical characteristics in the literature are ptosis, muscle fatigability or weakness, and ophthalmoplegia. CONCLUSION We present the case of a patient with biallelic variants in CHRNE gene including a variant of uncertain significance. Evaluation of variants of this gene, including the variant of uncertain significance identified in this case report, through further cases and studies may improve our understanding of Congenital Myasthenic Syndrome with Acetylcholine Receptor deficiency.
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Affiliation(s)
- Aashish Batheja
- School of Medicine, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Julie Bayer-Vile
- Department of Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Evan Silverstein
- Department of Ophthalmology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Natario Couser
- Department of Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
- Department of Ophthalmology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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Sarkar A, Panati K, Narala VR. Code inside the codon: The role of synonymous mutations in regulating splicing machinery and its impact on disease. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 790:108444. [PMID: 36307006 DOI: 10.1016/j.mrrev.2022.108444] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 10/10/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
In eukaryotes, precise pre-mRNA processing, including alternative splicing, is essential to carry out the intricate protein translation process. Both point mutations (that alter the translated protein sequence) and synonymous mutations (that do not alter the translated protein sequence) are capable of affecting the splicing process. Synonymous mutations are known to affect gene expression via altering mRNA stability, mRNA secondary structure, splicing processes, and translational kinetics. In higher eukaryotes, precise splicing is regulated by three weakly conserved cis-elements, 5' and 3' splice sites and the branch site. Many other cis-acting elements (exonic/intronic splicing enhancers and silencers) and trans-acting splicing factors (serine and arginine-rich proteins and heterogeneous nuclear ribonucleoproteins) have also been found to enhance or suppress the splicing process. The appearance of synonymous mutations in cis-acting elements can alter the splicing process by changing the binding pattern of splicing factors to exonic splicing enhancers or silencer motifs. This results in exon skipping, intron retention, and various other forms of alternative splicing, eventually leading to the emergence of a wide range of diseases. The focus of this review is to elucidate the role of synonymous mutations and their impact on abnormal splicing mechanisms. Further, this study highlights the function of synonymous mutation in mediating abnormal splicing in cancer and development of X-linked, and autosomal inherited diseases.
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Affiliation(s)
- Avik Sarkar
- Department of Zoology, Vidyasagar University, Midnapore, West Bengal 721102, India
| | - Kalpana Panati
- Department of Biotechnology, Government College for Men, Kadapa 516004, India
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Gómez-García de la Banda M, Simental-Aldaba E, Fahmy N, Sternberg D, Blondy P, Quijano-Roy S, Malfatti E. Case Report: A Novel AChR Epsilon Variant Causing a Clinically Discordant Salbutamol Responsive Congenital Myasthenic Syndrome in Two Egyptian Siblings. Front Neurol 2022; 13:909715. [PMID: 35720108 PMCID: PMC9201482 DOI: 10.3389/fneur.2022.909715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/02/2022] [Indexed: 12/05/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are inherited disorders that lead to abnormal neuromuscular transmission. Post-synaptic mutations are the main cause of CMS, particularly mutations in CHRNE. We report a novel homozygous CHRNE pathogenic variant in two Egyptian siblings showing a CMS. Interestingly, they showed different degrees of extraocular and skeletal muscle involvement; both presented only a partial response to cholinesterase inhibitors, and rapidly and substantially ameliorated after the addition of oral β2 adrenergic agonists. Here, we enlarge the genetic spectrum of CHRNE-related congenital myasthenic syndromes and highlight the importance of a β2 adrenergic agonists treatment.
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Affiliation(s)
- Marta Gómez-García de la Banda
- Pediatric Neurology and ICU Department, AP-HP Université Paris Saclay, Hôpital Raymond Poincaré, Garches, France
- Reference Center for Neuromuscular Diseases Centre “Nord- Est- Ile de France”, FILNEMUS, Creteil, France
- European Reference Center Network (Euro-NMD ERN), Paris, France
| | - Emmanuel Simental-Aldaba
- APHP, Centre de Référence de Pathologie Neuromusculaire Nord-Est-Ile-de-France, Henri Mondor University Hospital, Créteil, France
- Department of Neurorehabilitation, Instituto Nacional de Rehabilitación “LGII”, Mexico City, Mexico
| | - Nagia Fahmy
- Neuromuscular Unit, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Damien Sternberg
- European Reference Center Network (Euro-NMD ERN), Paris, France
- Service de Biochimie Métabolique, Centre de Génétique, Groupe Hospitalier Pitié-Salpêtrière, APHP Sorbonne Université, Paris, France
| | - Patricia Blondy
- European Reference Center Network (Euro-NMD ERN), Paris, France
| | - Susana Quijano-Roy
- Pediatric Neurology and ICU Department, AP-HP Université Paris Saclay, Hôpital Raymond Poincaré, Garches, France
- Reference Center for Neuromuscular Diseases Centre “Nord- Est- Ile de France”, FILNEMUS, Creteil, France
- European Reference Center Network (Euro-NMD ERN), Paris, France
- Centre de Recherche en Myologie, UMRS974, Paris, France
| | - Edoardo Malfatti
- Reference Center for Neuromuscular Diseases Centre “Nord- Est- Ile de France”, FILNEMUS, Creteil, France
- APHP, Centre de Référence de Pathologie Neuromusculaire Nord-Est-Ile-de-France, Henri Mondor University Hospital, Créteil, France
- Univ Paris Est Créteil, INSERM, IMRB, Créteil, France
- AP-HP, Hôpital Mondor, Service d'histologie, Créteil, France
- *Correspondence: Edoardo Malfatti
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Nicolau S, Milone M, Liewluck T. Guidelines for genetic testing of muscle and neuromuscular junction disorders. Muscle Nerve 2021; 64:255-269. [PMID: 34133031 DOI: 10.1002/mus.27337] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 12/24/2022]
Abstract
Despite recent advances in the understanding of inherited muscle and neuromuscular junction diseases, as well as the advent of a wide range of genetic tests, patients continue to face delays in diagnosis of sometimes treatable disorders. These guidelines outline an approach to genetic testing in such disorders. Initially, a patient's phenotype is evaluated to identify myopathies requiring directed testing, including myotonic dystrophies, facioscapulohumeral muscular dystrophy, oculopharyngeal muscular dystrophy, mitochondrial myopathies, dystrophinopathies, and oculopharyngodistal myopathy. Initial investigation in the remaining patients is generally a comprehensive gene panel by next-generation sequencing. Broad panels have a higher diagnostic yield and can be cost-effective. Due to extensive phenotypic overlap and treatment implications, genes responsible for congenital myasthenic syndromes should be included when evaluating myopathy patients. For patients whose initial genetic testing is negative or inconclusive, phenotypic re-evaluation is warranted, along with consideration of genes and variants not included initially, as well as their acquired mimickers.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Teerin Liewluck
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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Gül Mert G, Özcan N, Hergüner Ö, Altunbaşak Ş, Incecik F, Bişgin A, Ceylaner S. Congenital myasthenic syndrome in Turkey: clinical and genetic features in the long-term follow-up of patients. Acta Neurol Belg 2021; 121:529-534. [PMID: 31773638 DOI: 10.1007/s13760-019-01246-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 11/12/2019] [Indexed: 11/29/2022]
Abstract
Congenital Myasthenic Syndromes (CMS) are rare disorders that occur as a result of defects in the structure and in the function of neuromuscular junctions. Molecular genetic diagnosis is important to select the most suitable therapeutic option and treatment. Eight patients with congenital myasthenic syndromes who presented to the Çukurova University Pediatric Neurology Department Outpatient Clinic between June 2015 and May 2018 were reviewed. Mutations in the acetylcholine receptor (subunits in epsilon) (CHRNE) in three and mutations in the collagenic tail of endplate acetylcholinesterase (COLQ) gene in five patients were identified; p.W148 mutation was detected to be homozygous in four, c.1169A > G novel mutation in COLQ gene was homozygous in one, c452_454delAGG mutation was homozygous in the other patient, IVS7 + 2T > C(c.802 + 2T > C) mutation was homozygous in a patient and compound heterozygous mutations of c.865C > T(p.Leu289Phe) and c.872C > G(p.A2916)(p.Arg291Gly) in the CHRNE gene in the last patient. The parents of all the evaluated patients were consanguineous. Ptosis, ophthalmoplegia, generalized hypotonia, bulbar weakness, and respiratory crisis were the main findings at the time of presentation. Pyridostigmine is the first-line drug therapy in primary AChR deficiency. Beta adrenergic agonists, ephedrine, and albuterol are the other treatment options for CMS subtypes caused by mutations in COLQ. This study points out the genetic and phenotypic features of CMS patients in the Turkish population and it also reports previously unreported mutations in the literature. CHRNE and COLQ gene mutations are common in the Turkish population. Patients can get serious benefits and recover after the treatment. The treatment should be planned according to genetic tests and clinical findings.
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Affiliation(s)
- Gülen Gül Mert
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey.
| | - Neslihan Özcan
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Özlem Hergüner
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Şakir Altunbaşak
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Faruk Incecik
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Atıl Bişgin
- Department of Medical Genetics, Cukurova University Faculty of Medicine, Adana, Turkey
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Hodgman MW, Miller JB, Meurs TE, Kauwe JSK. CUBAP: an interactive web portal for analyzing codon usage biases across populations. Nucleic Acids Res 2020; 48:11030-11039. [PMID: 33045750 PMCID: PMC7641757 DOI: 10.1093/nar/gkaa863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/18/2020] [Accepted: 09/22/2020] [Indexed: 12/19/2022] Open
Abstract
Synonymous codon usage significantly impacts translational and transcriptional efficiency, gene expression, the secondary structure of both mRNA and proteins, and has been implicated in various diseases. However, population-specific differences in codon usage biases remain largely unexplored. Here, we present a web server, https://cubap.byu.edu, to facilitate analyses of codon usage biases across populations (CUBAP). Using the 1000 Genomes Project, we calculated and visually depict population-specific differences in codon frequencies, codon aversion, identical codon pairing, co-tRNA codon pairing, ramp sequences, and nucleotide composition in 17,634 genes. We found that codon pairing significantly differs between populations in 35.8% of genes, allowing us to successfully predict the place of origin for African and East Asian individuals with 98.8% and 100% accuracy, respectively. We also used CUBAP to identify a significant bias toward decreased CTG pairing in the immunity related GTPase M (IRGM) gene in East Asian and African populations, which may contribute to the decreased association of rs10065172 with Crohn's disease in those populations. CUBAP facilitates in-depth gene-specific and codon-specific visualization that will aid in analyzing candidate genes identified in genome-wide association studies, identifying functional implications of synonymous variants, predicting population-specific impacts of synonymous variants and categorizing genetic biases unique to certain populations.
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Affiliation(s)
- Matthew W Hodgman
- Department of Biology, Brigham Young University, Provo, UT 84602, USA
| | - Justin B Miller
- Department of Biology, Brigham Young University, Provo, UT 84602, USA
| | - Taylor E Meurs
- Department of Biology, Brigham Young University, Provo, UT 84602, USA
| | - John S K Kauwe
- Department of Biology, Brigham Young University, Provo, UT 84602, USA
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Sylvester B, Brindopke F, Suzuki A, Giron M, Auslander A, Maas RL, Tsai B, Gao H, Magee W, Cox TC, Sanchez-Lara PA. A Synonymous Exonic Splice Silencer Variant in IRF6 as a Novel and Cryptic Cause of Non-Syndromic Cleft Lip and Palate. Genes (Basel) 2020; 11:genes11080903. [PMID: 32784565 PMCID: PMC7465030 DOI: 10.3390/genes11080903] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/28/2020] [Accepted: 08/04/2020] [Indexed: 12/31/2022] Open
Abstract
Missense, nonsense, splice site and regulatory region variants in interferon regulatory factor 6 (IRF6) have been shown to contribute to both syndromic and non-syndromic forms of cleft lip and/or palate (CL/P). We report the diagnostic evaluation of a complex multigeneration family of Honduran ancestry with a pedigree structure consistent with autosomal-dominant inheritance with both incomplete penetrance and variable expressivity. The proband's grandmother bore children with two partners and CL/P segregates on both sides of each lineage. Through whole-exome sequencing of five members of the family, we identified a single shared synonymous variant, located in the middle of exon 7 of IRF6 (p.Ser307Ser; g.209963979 G>A; c.921C>T). The variant was shown to segregate in the seven affected individuals and through three unaffected obligate carriers, spanning both sides of this pedigree. This variant is very rare, only being found in three (all of Latino ancestry) of 251,352 alleles in the gnomAD database. While the variant did not create a splice acceptor/donor site, in silico analysis predicted it to impact an exonic splice silencer element and the binding of major splice regulatory factors. In vitro splice assays supported this by revealing multiple abnormal splicing events, estimated to impact >60% of allelic transcripts. Sequencing of the alternate splice products demonstrated the unmasking of a cryptic splice site six nucleotides 5' of the variant, as well as variable utilization of cryptic splice sites in intron 6. The ectopic expression of different splice regulatory proteins altered the proportion of abnormal splicing events seen in the splice assay, although the alteration was dependent on the splice factor. Importantly, each alternatively spliced mRNA is predicted to result in a frame shift and prematurely truncated IRF6 protein. This is the first study to identify a synonymous variant as a likely cause of NS-CL/P and highlights the care that should be taken by laboratories when considering and interpreting variants.
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Affiliation(s)
- Beau Sylvester
- Division of Plastic and Maxillofacial Surgery, Children’s Hospital Los Angeles, Los Angeles, CA 90027, USA; (B.S.); (A.A.); (W.M.III)
| | | | - Akiko Suzuki
- Department of Oral & Craniofacial Sciences, University of Missouri-Kansas City School of Dentistry, Kansas City, MO 64108, USA; (A.S.); (T.C.C.)
| | - Melissa Giron
- Operación Sonrisa Honduras, Tegucigalpa 11101, Honduras;
| | - Allyn Auslander
- Division of Plastic and Maxillofacial Surgery, Children’s Hospital Los Angeles, Los Angeles, CA 90027, USA; (B.S.); (A.A.); (W.M.III)
- Department of Preventive Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA
| | - Richard L. Maas
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
| | - Becky Tsai
- Fulgent Genetics, Temple City, CA 91780, USA; (B.T.); (H.G.)
| | - Hanlin Gao
- Fulgent Genetics, Temple City, CA 91780, USA; (B.T.); (H.G.)
| | - William Magee
- Division of Plastic and Maxillofacial Surgery, Children’s Hospital Los Angeles, Los Angeles, CA 90027, USA; (B.S.); (A.A.); (W.M.III)
| | - Timothy C. Cox
- Department of Oral & Craniofacial Sciences, University of Missouri-Kansas City School of Dentistry, Kansas City, MO 64108, USA; (A.S.); (T.C.C.)
- Department of Pediatrics, University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108, USA
| | - Pedro A. Sanchez-Lara
- Department of Pediatrics, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90048, USA
- Correspondence: ; Tel.: +1-(310)-423-4461
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Yang K, Cheng H, Yuan F, Meng L, Yin R, Zhang Y, Wang S, Wang C, Lu Y, Xi J, Lu Q, Chen Y. CHRNE compound heterozygous mutations in congenital myasthenic syndrome: A case report. Medicine (Baltimore) 2018; 97:e0347. [PMID: 29702980 PMCID: PMC5944527 DOI: 10.1097/md.0000000000010347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
RATIONALE Congenital myasthenic syndrome (CMSs) are a group of rare genetic disorders of the neurological junction, which can result in structural or functional weakness. Here, we characterized a case of CMS in order to clarify the diagnosis and expand the understanding of it. The molecular diagnosis had implications for choice of treatment and genetic counseling. PATIENT CONCERNS A 3-year-old male patient with CMS had ptosis and limb weakness for 2 months after birth. Clinical course and electrophysiological, imaging, and genetic findings were assessed. Protein structure/function was predicted. A novel mutation of c.295C>T (exon 4) and another known mutation of c.442T>A (exon 5) were found in CHRNE. Both mutations localized in conserved sequences. The c.442T>A (p.C148S) missense mutation in CHRNE was predicted to be damaging/deleterious. The iterative threading assembly refinement (I-TASSER) server generated vastly different 3-dimensional (3D) atomic models based on protein sequences from wide-type and novel nonsense mutation of c.295C>T (p.R99X) in CHRNE. DIAGNOSES The diagnosis of CMS with CHRNE mutations in Han Chinese was confirmed. INTERVENTIONS The patient was given prednisone (10 mg, once daily, taken orally) and pyridostigmine (15 mg, three times a day, taken orally). OUTCOMES The patient had a moderate response to prednisone and pyridostigmine. LESSONS We expanded the genotype and phenotype of CMS with CHRNE mutations in Han Chinese and provided new insights into the molecular mechanism of CMS and help to the diagnosis and treatment of CMS.
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Affiliation(s)
| | | | | | - Linyi Meng
- Department of Pharmacy, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China
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Tan JZ, Man Y, Xiao F. A Missense Mutation in Epsilon-subunit of Acetylcholine Receptor Causing Autosomal Dominant Slow-channel Congenital Myasthenic Syndrome in a Chinese Family. Chin Med J (Engl) 2017; 129:2596-2602. [PMID: 27779167 PMCID: PMC5125339 DOI: 10.4103/0366-6999.192780] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Congenital myasthenic syndromes are a group of rare disorders that are clinically and genetically heterogeneous and caused by mutations in the genes encoding proteins of the neuromuscular junction. Here, we described a Chinese family that presented with phenotypes of classic slow-channel congenital myasthenic syndrome (SCCMS). METHODS Clinical characteristics and electrophysiological features of three patients from a Chinese family were examined, and next-generation sequencing followed by direct sequencing was carried out. RESULTS The patients revealed variability in clinical and electrophysiological features. However, weakness, scoliosis, and repetitive-compound muscle action potential were found in all affected members in the family. A heterozygous C>T missense mutation at nucleotide 865 in acetylcholine receptor epsilon-subunit (CHRNE) gene that causes a leucine-to-phenylalanine substitution at position 289 (L289F) was found. CONCLUSIONS We reported a SCCMS family of Chinese origin. In the family, classical clinical phenotype with phenotypic variability among different members was found. Genetic testing could help diagnose this rare disease.
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Affiliation(s)
- Jia-Ze Tan
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Yuan Man
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
| | - Fei Xiao
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China
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Diederichs S, Bartsch L, Berkmann JC, Fröse K, Heitmann J, Hoppe C, Iggena D, Jazmati D, Karschnia P, Linsenmeier M, Maulhardt T, Möhrmann L, Morstein J, Paffenholz SV, Röpenack P, Rückert T, Sandig L, Schell M, Steinmann A, Voss G, Wasmuth J, Weinberger ME, Wullenkord R. The dark matter of the cancer genome: aberrations in regulatory elements, untranslated regions, splice sites, non-coding RNA and synonymous mutations. EMBO Mol Med 2016; 8:442-57. [PMID: 26992833 PMCID: PMC5126213 DOI: 10.15252/emmm.201506055] [Citation(s) in RCA: 180] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cancer is a disease of the genome caused by oncogene activation and tumor suppressor gene inhibition. Deep sequencing studies including large consortia such as TCGA and ICGC identified numerous tumor‐specific mutations not only in protein‐coding sequences but also in non‐coding sequences. Although 98% of the genome is not translated into proteins, most studies have neglected the information hidden in this “dark matter” of the genome. Malignancy‐driving mutations can occur in all genetic elements outside the coding region, namely in enhancer, silencer, insulator, and promoter as well as in 5′‐UTR and 3′‐UTR. Intron or splice site mutations can alter the splicing pattern. Moreover, cancer genomes contain mutations within non‐coding RNA, such as microRNA, lncRNA, and lincRNA. A synonymous mutation changes the coding region in the DNA and RNA but not the protein sequence. Importantly, oncogenes such as TERT or miR‐21 as well as tumor suppressor genes such as TP53/p53,APC,BRCA1, or RB1 can be affected by these alterations. In summary, coding‐independent mutations can affect gene regulation from transcription, splicing, mRNA stability to translation, and hence, this largely neglected area needs functional studies to elucidate the mechanisms underlying tumorigenesis. This review will focus on the important role and novel mechanisms of these non‐coding or allegedly silent mutations in tumorigenesis.
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Affiliation(s)
- Sven Diederichs
- Division of Cancer Research, Department of Thoracic Surgery, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany Division of RNA Biology & Cancer (B150), German Cancer Research Center (DKFZ), Heidelberg, Germany German Cancer Consortium (DKTK), Freiburg, Germany
| | - Lorenz Bartsch
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Julia C Berkmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Karin Fröse
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Jana Heitmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Caroline Hoppe
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Deetje Iggena
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Danny Jazmati
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Philipp Karschnia
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Miriam Linsenmeier
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Thomas Maulhardt
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Lino Möhrmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Johannes Morstein
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Stella V Paffenholz
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Paula Röpenack
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Timo Rückert
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Ludger Sandig
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Maximilian Schell
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Anna Steinmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Gjendine Voss
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Jacqueline Wasmuth
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Maria E Weinberger
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Ramona Wullenkord
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
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Hunt RC, Simhadri VL, Iandoli M, Sauna ZE, Kimchi-Sarfaty C. Exposing synonymous mutations. Trends Genet 2014; 30:308-21. [PMID: 24954581 DOI: 10.1016/j.tig.2014.04.006] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 12/12/2022]
Abstract
Synonymous codon changes, which do not alter protein sequence, were previously thought to have no functional consequence. Although this concept has been overturned in recent years, there is no unique mechanism by which these changes exert biological effects. A large repertoire of both experimental and bioinformatic methods has been developed to understand the effects of synonymous variants. Results from this body of work have provided global insights into how biological systems exploit the degeneracy of the genetic code to control gene expression, protein folding efficiency, and the coordinated expression of functionally related gene families. Although it is now clear that synonymous variants are important in a variety of contexts, from human disease to the safety and efficacy of therapeutic proteins, there is no clear consensus on the approaches to identify and validate these changes. Here, we review the diverse methods to understand the effects of synonymous mutations.
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Affiliation(s)
- Ryan C Hunt
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA.
| | - Vijaya L Simhadri
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA
| | - Matthew Iandoli
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA
| | - Zuben E Sauna
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA.
| | - Chava Kimchi-Sarfaty
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA.
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Zhou T, Ko EA, Gu W, Lim I, Bang H, Ko JH. Non-silent story on synonymous sites in voltage-gated ion channel genes. PLoS One 2012; 7:e48541. [PMID: 23119053 PMCID: PMC3485311 DOI: 10.1371/journal.pone.0048541] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 09/26/2012] [Indexed: 02/06/2023] Open
Abstract
Synonymous mutations are usually referred to as “silent”, but increasing evidence shows that they are not neutral in a wide range of organisms. We looked into the relationship between synonymous codon usage bias and residue importance of voltage-gated ion channel proteins in mice, rats, and humans. We tested whether translationally optimal codons are associated with transmembrane or channel-forming regions, i.e., the sites that are particularly likely to be involved in the closing and opening of an ion channel. Our hypothesis is that translationally optimal codons are preferred at the sites within transmembrane domains or channel-forming regions in voltage-gated ion channel genes to avoid mistranslation-induced protein misfolding or loss-of-function. Using the Mantel-Haenszel procedure, which applies to categorical data, we found that translationally optimal codons are more likely to be used at transmembrane residues and the residues involved in channel-forming. We also found that the conservation level at synonymous sites in the transmembrane region is significantly higher than that in the non-transmembrane region. This study provides evidence that synonymous sites in voltage-gated ion channel genes are not neutral. Silent mutations at channel-related sites may lead to dysfunction of the ion channel.
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Affiliation(s)
- Tong Zhou
- Institute for Personalized Respiratory Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- Section of Pulmonary, Critical Care, Sleep & Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Eun A. Ko
- Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Wanjun Gu
- Key Laboratory of Child Development and Learning Science of Ministry of Education of China, Southeast University, Nanjing, Jiangsu, China
| | - Inja Lim
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, South Korea
| | - Hyoweon Bang
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, South Korea
| | - Jae-Hong Ko
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, South Korea
- * E-mail:
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13
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Scott AP, Laing NG, Mastaglia F, Dalakas M, Needham M, Allcock RJN. Investigation of NOTCH4 coding region polymorphisms in sporadic inclusion body myositis. J Neuroimmunol 2012; 250:66-70. [PMID: 22732452 DOI: 10.1016/j.jneuroim.2012.04.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/27/2012] [Accepted: 04/29/2012] [Indexed: 01/26/2023]
Abstract
The NOTCH4 gene, located within the MHC region, is involved in cellular differentiation and has varying effects dependent on tissue type. Coding region polymorphisms haplotypic of the sIBM-associated 8.1 ancestral haplotype were identified in NOTCH4 and genotyped in two different Caucasian sIBM cohorts. In both cohorts the frequency of the minor allele of rs422951 and the 12-repeat variation for rs72555375 was increased and was higher than the frequency of the sIBM-associated allele HLA-DRB1*0301. These NOTCH4 polymorphisms can be considered to be markers for sIBM susceptibility, but require further investigation to determine whether they are directly involved in the disease pathogenesis.
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Affiliation(s)
- Adrian P Scott
- School of Pathology and Laboratory Medicine, M504, University of Western Australia, Stirling Highway, Nedlands 6009, Perth, Australia.
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Chikova A, Grando SA. Naturally occurring variants of human Α9 nicotinic receptor differentially affect bronchial cell proliferation and transformation. PLoS One 2011; 6:e27978. [PMID: 22125646 PMCID: PMC3220719 DOI: 10.1371/journal.pone.0027978] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 10/28/2011] [Indexed: 02/06/2023] Open
Abstract
Isolation of polyadenilated mRNA from human immortalized bronchial epithelial cell line BEP2D revealed the presence of multiple isoforms of RNA coded by the CHRNA9 gene for α9 nicotinic acetylcholine receptor (nAChR). BEP2D cells were homozygous for the rs10009228 polymorphism encoding for N442S amino acid substitution, and also contained mRNA coding for several truncated isoforms of α9 protein. To elucidate the biologic significance of the naturally occurring variants of α9 nAChR, we compared the biologic effects of overexpression of full-length α9 N442 and S442 proteins, and the truncated α9 variant occurring due to a loss of the exon 4 sequence that causes frame shift and early termination of the translation. These as well as control vector were overexpressed in the BEP2D cells that were used in the assays of proliferation rate, spontaneous vs. tobacco nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced cellular transformation, and tumorigenicity in cell culture and mice. Overexpression of the S442 variant significantly increased cellular proliferation, and spontaneous and NNK-induced transformation. The N442 variant significantly decreased cellular transformation, without affecting proliferation rate. Overexpression of the truncated α9 significantly decreased proliferation and suppressed cellular transformation. These results suggested that α9 nAChR plays important roles in regulation of bronchial cell growth by endogenous acetylcholine and exogenous nicotine, and susceptibility to NNK-induced carcinogenic transformation. The biologic activities of α9 nAChR may be regulated at the splicing level, and genetic polymorphisms in CHRNA9 affecting protein levels, amino acid sequence and RNA splicing may influence the risk for lung cancer.
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Affiliation(s)
- Anna Chikova
- Department of Dermatology, University of California Irvine, Irvine, California, United States of America
- The D.I. Ivanovsky Institute of Virology of The Ministry of Health of The Russian Federation, Moscow, Russia
| | - Sergei A. Grando
- Department of Dermatology, University of California Irvine, Irvine, California, United States of America
- Cancer Center and Research Institute, University of California Irvine, Irvine, California, United States of America
- * E-mail:
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15
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Brenner L, Burke K, Leduc CA, Guha S, Guo J, Chung WK. Novel splice mutation in microthalmia-associated transcription factor in Waardenburg Syndrome. Genet Test Mol Biomarkers 2011; 15:525-9. [PMID: 21438779 DOI: 10.1089/gtmb.2010.0277] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Waardenburg Syndrome (WS) is a syndromic form of hearing loss associated with mutations in six different genes. We identified a large family with WS that had previously undergone clinical testing, with no reported pathogenic mutation. Using linkage analysis, a region on 3p14.1 with an LOD score of 6.6 was identified. Microthalmia-Associated Transcription Factor, a gene known to cause WS, is located within this region of linkage. Sequencing of Microthalmia-Associated Transcription Factor demonstrated a c.1212 G>A synonymous variant that segregated with the WS in the family and was predicted to cause a novel splicing site that was confirmed with expression analysis of the mRNA. This case illustrates the need to computationally analyze novel synonymous sequence variants for possible effects on splicing to maximize the clinical sensitivity of sequence-based genetic testing.
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Affiliation(s)
- Laura Brenner
- Department of Pediatrics, Columbia University, New York, New York 10032, USA
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16
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Müller JS, Mihaylova V, Abicht A, Lochmüller H. Congenital myasthenic syndromes: spotlight on genetic defects of neuromuscular transmission. Expert Rev Mol Med 2007; 9:1-20. [PMID: 17686188 DOI: 10.1017/s1462399407000427] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The neuromuscular junction (NMJ) is a complex structure that efficiently communicates the electrical impulse from the motor neuron to the skeletal muscle to induce muscle contraction. Genetic and autoimmune disorders known to compromise neuromuscular transmission are providing further insights into the complexities of NMJ function. Congenital myasthenic syndromes (CMSs) are a genetically and phenotypically heterogeneous group of rare hereditary disorders affecting neuromuscular transmission. The understanding of the molecular basis of the different types of CMSs has evolved rapidly in recent years. Mutations were first identified in the subunits of the nicotinic acetylcholine receptor (AChR), but now mutations in ten different genes - encoding post-, pre- or synaptic proteins - are known to cause CMSs. Pathogenic mechanisms leading to an impaired neuromuscular transmission modify AChRs or endplate structure or lead to decreased acetylcholine synthesis and release. However, the genetic background of many CMS forms is still unresolved. A precise molecular classification of CMS type is of paramount importance for the diagnosis, counselling and therapy of a patient, as different drugs may be beneficial or deleterious depending on the molecular background of the particular CMS.
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Affiliation(s)
- Juliane S Müller
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
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