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Geroldi A, Mammi A, Gaudio A, Patrone S, La Barbera A, Origone P, Ponti C, Sanguineri F, Massucco S, Marinelli L, Grandis M, Schenone A, Mandich P, Bellone E, Gotta F. Next-generation sequencing in Charcot-Marie-Tooth: a proposal for improvement of ACMG guidelines for variant evaluation. J Med Genet 2024; 61:847-852. [PMID: 38871447 DOI: 10.1136/jmg-2024-110019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 06/04/2024] [Indexed: 06/15/2024]
Abstract
BACKGROUND The application of massive parallel sequencing technologies in the molecular analysis of Charcot-Marie-Tooth (CMT) has enabled the rapid and cost-effective identification of numerous potentially significant variants for diagnostic purposes. The objective is to reduce the number of variants, focusing only on those with pathogenic significance. The 2015 American College of Medical Genetics and Genomics (ACMG) guidelines aid in achieving this goal, but it is now evident that a pathology or gene-specific review of these rules is essential to avoid misinterpretations that may result from blindly applying the criteria. This study demonstrates how revised ACMG criteria, combined with CMT-specific literature data and expertise, can alter the final classification of a variant. METHODS We reviewed ACMG criteria based on current knowledge of CMT and provided suggestions for adapting them to the specificities of CMT. RESULTS Of the 226 index patients analysed, a diagnostic yield of 20% was obtained. It is worth noting that the 9% of cases had their final diagnosis changed with the application of the revised criteria, often resulting in the loss of the pathogenic classification of a variant. CONCLUSIONS The widespread availability of high-throughput sequencing technologies has enabled genetic testing even for laboratories without specific disease expertise. Disease-specific ACMG criteria can be a valuable tool to prevent the proliferation of variants of uncertain significance and the misinterpretation of variants.
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Affiliation(s)
- Alessandro Geroldi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
| | - Alessia Mammi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Andrea Gaudio
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Serena Patrone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
| | - Andrea La Barbera
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Paola Origone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Clarissa Ponti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Francesca Sanguineri
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Sara Massucco
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Neurology Clinic, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Lucio Marinelli
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Neurology Clinic, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Marina Grandis
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Neurology Clinic, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Angelo Schenone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Neurology Clinic, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Paola Mandich
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Emilia Bellone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and Maternal and Infantile Sciences, University of Genoa, Genova, Italy
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Fabio Gotta
- UOC Medical Genetics, IRCCS Ospedale Policlinico San Martino, Genova, Italy
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Li Z, Zeng S, Xie Y, Li X, Huang S, Zhao H, Cao W, Liu L, Wang M, Gong Q, Liu J, Rong P, Zhang R. Genetic and clinical profile of 15 Chinese families with GDAP1-related Charcot-Marie-Tooth disease and identification of H256R as a frequent mutation. J Peripher Nerv Syst 2024; 29:232-242. [PMID: 38705839 DOI: 10.1111/jns.12628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 05/07/2024]
Abstract
BACKGROUND AND AIMS Mutations in ganglioside-induced differentiation-associated protein 1 (GDAP1) cause axonal or demyelinating Charcot-Marie-Tooth disease (CMT) with autosomal dominant or recessive inheritance. In this study, we aim to report the genotypic and phenotypic features of GDAP1-related CMT in a Chinese cohort. METHODS Clinical, neurophysiological, genetic data, and available muscle/brain imaging information of 28 CMT patients with GDAP1 variants were retrospectively collected. RESULTS We identified 16 GDAP1 pathogenic variants, among which two novel variants c.980dup(p.L328FfsX25) and c.480+4T>G were first reported. Most patients (16/28) presented with AR or AD CMT2K phenotype. Clinical characteristics in our cohort demonstrated that the AR patients presented earlier onset, more severe phenotype compared with the AD patients. Considerable intra-familial phenotypic variability was observed among three AD families. Muscle atrophy and fatty infiltration in the lower extremity were detected by Muscle magnetic resonance imaging (MRI) scans in four patients. MRI showed two AR patients showed more severe muscle involvement of the posterior compartment than those of the anterolateral compartment in the calf. One patient carrying Q38*/H256R variants accompanied with mild periventricular leukoaraiosis. CONCLUSIONS In this study, we conducted an analysis of clinical features of the GDAP1-related CMT patients, expanded the mutation spectrum in GDAP1 by reporting two novel variants, and presented the prevalent occurrence of the H256R mutation in China. The screening of GDAP1 should be particularly emphasized in Chinese patients with CMT2, given the incomplete penetrance and pathogenic inheritance patterns involving dominant and recessive modes.
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Affiliation(s)
- Zhongzheng Li
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Sen Zeng
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yongzhi Xie
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Xiaobo Li
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Shunxiang Huang
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Huadong Zhao
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Wanqian Cao
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Lei Liu
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Mengli Wang
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Qiaoyu Gong
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Jun Liu
- Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Pengfei Rong
- Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Ruxu Zhang
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
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Parmar JM, Laing NG, Kennerson ML, Ravenscroft G. Genetics of inherited peripheral neuropathies and the next frontier: looking backwards to progress forwards. J Neurol Neurosurg Psychiatry 2024:jnnp-2024-333436. [PMID: 38744462 DOI: 10.1136/jnnp-2024-333436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/10/2024] [Indexed: 05/16/2024]
Abstract
Inherited peripheral neuropathies (IPNs) encompass a clinically and genetically heterogeneous group of disorders causing length-dependent degeneration of peripheral autonomic, motor and/or sensory nerves. Despite gold-standard diagnostic testing for pathogenic variants in over 100 known associated genes, many patients with IPN remain genetically unsolved. Providing patients with a diagnosis is critical for reducing their 'diagnostic odyssey', improving clinical care, and for informed genetic counselling. The last decade of massively parallel sequencing technologies has seen a rapid increase in the number of newly described IPN-associated gene variants contributing to IPN pathogenesis. However, the scarcity of additional families and functional data supporting variants in potential novel genes is prolonging patient diagnostic uncertainty and contributing to the missing heritability of IPNs. We review the last decade of IPN disease gene discovery to highlight novel genes, structural variation and short tandem repeat expansions contributing to IPN pathogenesis. From the lessons learnt, we provide our vision for IPN research as we anticipate the future, providing examples of emerging technologies, resources and tools that we propose that will expedite the genetic diagnosis of unsolved IPN families.
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Affiliation(s)
- Jevin M Parmar
- Rare Disease Genetics and Functional Genomics, Harry Perkins Institute of Medical Research, Perth, Western Australia, Australia
- Centre for Medical Research, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Nigel G Laing
- Centre for Medical Research, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Preventive Genetics, Harry Perkins Institute of Medical Research, Perth, Western Australia, Australia
| | - Marina L Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Concord, New South Wales, Australia
- Molecular Medicine Laboratory, Concord Hospital, Concord, New South Wales, Australia
| | - Gianina Ravenscroft
- Rare Disease Genetics and Functional Genomics, Harry Perkins Institute of Medical Research, Perth, Western Australia, Australia
- Centre for Medical Research, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
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Kabzińska D, Chabros K, Kamińska J, Kochański A. The GDAP1 p.Glu222Lys Variant-Weak Pathogenic Effect, Cumulative Effect of Weak Sequence Variants, or Synergy of Both Factors? Genes (Basel) 2022; 13:genes13091546. [PMID: 36140714 PMCID: PMC9498914 DOI: 10.3390/genes13091546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 11/24/2022] Open
Abstract
Charcot−Marie−Tooth disorders (CMT) represent a highly heterogeneous group of diseases of the peripheral nervous system in which more than 100 genes are involved. In some CMT patients, a few weak sequence variants toward other CMT genes are detected instead of one leading CMT mutation. Thus, the presence of a few variants in different CMT-associated genes raises the question concerning the pathogenic status of one of them. In this study, we aimed to analyze the pathogenic effect of c.664G>A, p.Glu222Lys variant in the GDAP1 gene, whose mutations are known to be causative for CMT type 4A (CMT4A). Due to low penetrance and a rare occurrence limited to five patients from two Polish families affected by the CMT phenotype, there is doubt as to whether we are dealing with real pathogenic mutation. Thus, we aimed to study the pathogenic effect of the c.664G>A, p.Glu222Lys variant in its natural environment, i.e., the neuronal SH-SY5Y cell line. Additionally, we have checked the pathogenic status of p.Glu222Lys in the broader context of the whole exome. We also have analyzed the impact of GDAP1 gene mutations on the morphology of the transfected cells. Despite the use of several tests to determine the pathogenicity of the p.Glu222Lys variant, we cannot point to one that would definitively solve the problem of pathogenicity.
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Affiliation(s)
- Dagmara Kabzińska
- Neuromuscular Unit, Mossakowski Medical Research Institute Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Katarzyna Chabros
- Neuromuscular Unit, Mossakowski Medical Research Institute Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Joanna Kamińska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Andrzej Kochański
- Neuromuscular Unit, Mossakowski Medical Research Institute Polish Academy of Sciences, 02-106 Warsaw, Poland
- Correspondence:
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