Clinical and genetic characterisation of a large Indian congenital myasthenic syndrome cohort.

Autor: Polavarapu K; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India.; Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada., Sunitha B; John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK.; Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge CB2 0SP, UK.; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK., Töpf A; John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK., Preethish-Kumar V; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India.; Department of Neurology, Neurofoundation, Salem, Tamil Nadu 636009, India., Thompson R; Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada., Vengalil S; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Nashi S; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Bardhan M; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Sanka SB; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Huddar A; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India.; Department of Neurology, St Johns Medical College Hospital, Bangalore 560034, India., Unnikrishnan G; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India.; Department of Neurology, Amruta Institute of Medical Sciences, Kochi 682041, India., Arunachal G; Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru 560029, India., Girija MS; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Porter A; John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK., Azuma Y; John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK., Lorenzoni PJ; Neuromuscular Disorders Division, Service of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal do Paraná, Rua General Carneiro, Curitiba - PR 80060-900, Brazil., Baskar D; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Anjanappa RM; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Keertipriya M; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Padmanabh H; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Harikrishna GV; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Laurie S; Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain., Matalonga L; Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain., Horvath R; Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge CB2 0SP, UK., Nalini A; Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India., Lochmüller H; Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada.; Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain.; Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada.; Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON K1H 8M5, Canada.; Department of Neuropediatrics and Muscle Disorders, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79110, Germany.
Jazyk: angličtina
Zdroj: Brain : a journal of neurology [Brain] 2024 Jan 04; Vol. 147 (1), pp. 281-296.
DOI: 10.1093/brain/awad315
Abstrakt: Congenital myasthenic syndromes (CMS) are a rare group of inherited disorders caused by gene defects associated with the neuromuscular junction and potentially treatable with commonly available medications such as acetylcholinesterase inhibitors and β2 adrenergic receptor agonists. In this study, we identified and genetically characterized the largest cohort of CMS patients from India to date. Genetic testing of clinically suspected patients evaluated in a South Indian hospital during the period 2014-19 was carried out by standard diagnostic gene panel testing or using a two-step method that included hotspot screening followed by whole-exome sequencing. In total, 156 genetically diagnosed patients (141 families) were characterized and the mutational spectrum and genotype-phenotype correlation described. Overall, 87 males and 69 females were evaluated, with the age of onset ranging from congenital to fourth decade (mean 6.6 ± 9.8 years). The mean age at diagnosis was 19 ± 12.8 (1-56 years), with a mean diagnostic delay of 12.5 ± 9.9 (0-49 years). Disease-causing variants in 17 CMS-associated genes were identified in 132 families (93.6%), while in nine families (6.4%), variants in genes not associated with CMS were found. Overall, postsynaptic defects were most common (62.4%), followed by glycosylation defects (21.3%), synaptic basal lamina genes (4.3%) and presynaptic defects (2.8%). Other genes found to cause neuromuscular junction defects (DES, TEFM) in our cohort accounted for 2.8%. Among the individual CMS genes, the most commonly affected gene was CHRNE (39.4%), followed by DOK7 (14.4%), DPAGT1 (9.8%), GFPT1 (7.6%), MUSK (6.1%), GMPPB (5.3%) and COLQ (4.5%). We identified 22 recurrent variants in this study, out of which eight were found to be geographically specific to the Indian subcontinent. Apart from the known common CHRNE variants p.E443Kfs*64 (11.4%) and DOK7 p.A378Sfs*30 (9.3%), we identified seven novel recurrent variants specific to this cohort, including DPAGT1 p.T380I and DES c.1023+5G>A, for which founder haplotypes are suspected. This study highlights the geographic differences in the frequencies of various causative CMS genes and underlines the increasing significance of glycosylation genes (DPAGT1, GFPT1 and GMPPB) as a cause of neuromuscular junction defects. Myopathy and muscular dystrophy genes such as GMPPB and DES, presenting as gradually progressive limb girdle CMS, expand the phenotypic spectrum. The novel genes MACF1 and TEFM identified in this cohort add to the expanding list of genes with new mechanisms causing neuromuscular junction defects.
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Databáze: MEDLINE
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