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DOI: 10.1590/0004-282X-ANP-2020-0575
Congenital myasthenic syndrome in a cohort of patients with ‘double’ seronegative myasthenia gravis
Síndrome miastênica congênita em uma série de pacientes com miastenia gravis duplo soronegativa
ABSTRACT
Background: Congenital myasthenic syndromes (CMS) have some phenotypic overlap with seronegative myasthenia gravis (SNMG). Objective: The aim of this single center study was to assess the minimum occurrence of CMS misdiagnosed as double SNMG in a Brazilian cohort. Methods: The genetic analysis of the most common mutations in CHRNE, RAPSN, and DOK7 genes was used as the main screening tool. Results: We performed genetic analysis in 22 patients with a previous diagnosis of ‘double’ SNMG. In this study, one CMS patient was confirmed due to the presence of compound heterozygous variants in the CHRNE gene (c.130insG/p.Cys210Phe). Conclusions: This study confirmed that CMS due to CHNRE mutations can be mistaken for SNMG. In addition, our study estimated the prevalence of misdiagnosed CMS to be 4.5% in ‘double’ SNMG patients of our center. Based on our findings, genetic screening could be helpful in the diagnostic workup of patients with ‘double’ SNMG in whom differential diagnosis is recommended.
RESUMO
Antecedentes: As síndromes miastênicas congênitas (SMC) podem ter sobreposição fenotípica com a miastenia gravis soronegativa (MG-SN). Objetivo: Estabelecer a prevalência mínima de SMC diagnosticada inicialmente como MG duplo soronegativa em uma série de casos brasileiros. Métodos: A análise genética das mutações mais comuns nos genes CHRNE, RAPSN e DOK7 foi usada como o principal exame de triagem. Resultados: Vinte e dois pacientes com diagnóstico prévio de MG-SN foram geneticamente analisados, sendo que uma paciente foi confirmada com SMC devido a presença de variante em heterozigose composta no gene CHRNE (c.130insG/p.Cys210Phe). Conclusões: O presente estudo confirma que SMC devido mutação no gene CHNRE pode ser inicialmente diagnosticada como MG-SN. O estudo estimou como 4,5% a prevalência de diagnóstico de SMC entre nossos pacientes préviamente diagnosticados como MG-SN. Com base nesse estudo, a análise genética pode ser recomendada para investigação do diagnóstico diferencial em pacientes com MG-SN.
Authors’ contributions:
PJL: conceptualization, data curation, formal analysis, investigation, methodology, project administration, validation, writing-original draft, writing-review & editing; RDD: data curation, investigation, writing-review & editing; RCA, NMCH: formal analysis, methodology, writing-review & editing; OHF: investigation, writing-review & editing; AT, HL: methodology, writing-review & editing; LCW: data curation, investigation, supervision, writing-review & editing; CSKK: data curation, formal analysis, investigation, supervision, writing-review & editing; RHS: conceptualization, data curation, formal analysis, funding acquisition, investigation, methodology, project administration, supervision, validation, visualization, writing-original draft, writing-review & editing.
Support
This study was supported by Universidade Federal do Paraná (UFPR) and Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq).
Publication History
Received: 08 December 2020
Accepted: 27 February 2021
Article published online:
30 January 2023
© 2021. Academia Brasileira de Neurologia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)
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