Successful treatment of congenital myasthenic syndrome caused by a novel compound heterozygous variant in RAPSN.
Congenital myasthenic syndrome
Exome sequencing
Gross Motor Function Measure (GMFM)-88
Intronic insertion
Pyridostigmine
RAPSN
Reverse transcription polymerase chain reaction (RT-PCR)
Journal
Brain & development
ISSN: 1872-7131
Titre abrégé: Brain Dev
Pays: Netherlands
ID NLM: 7909235
Informations de publication
Date de publication:
Jan 2022
Jan 2022
Historique:
received:
18
05
2021
revised:
29
08
2021
accepted:
05
09
2021
pubmed:
28
9
2021
medline:
3
3
2022
entrez:
27
9
2021
Statut:
ppublish
Résumé
Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous neuromuscular disorder characterized by muscle weakness and caused by mutations in more than 35 different genes. This condition should not be overlooked as a subset of patients with CMS are treatable. However, the diagnosis of CMS is often difficult due to the broad variability in disease severity and course. A five-year-old boy without remarkable family history was born with marked general muscle hypotonia and weakness, respiratory insufficiency, anomalies, and multiple joint contractures. Congenital myopathy was suspected based upon type 1 fiber predominance on muscle biopsy. However, he was diagnosed with CMS at age 4 years when his ptosis and ophthalmoplegia were found to be improved by edrophonium chloride and repetitive nerve stimulation showed attenuation of compound muscle action potentials. An exome sequencing identified a compound heterozygous missense variant of c.737C > T (p.A246V) and a novel intronic insertion c.1166 + 4_1166 + 5insAAGCCCACCAC in RAPSN. RT-PCR analysis which showed the skipping of exon 7 in a skeletal muscle sample confirmed that the intronic insertion was pathogenic. His myasthenic symptoms were remarkably improved by pyridostigmine. The patient's diagnosis of CMS was confirmed by exome sequencing, and RT-PCR revealed that the skipping of exon 7 in RAPSN was caused by a novel intronic insertion. The genetic information uncovered in this case should therefore be added to the collection of tools for diagnosing and treating CMS.
Sections du résumé
BACKGROUND
BACKGROUND
Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous neuromuscular disorder characterized by muscle weakness and caused by mutations in more than 35 different genes. This condition should not be overlooked as a subset of patients with CMS are treatable. However, the diagnosis of CMS is often difficult due to the broad variability in disease severity and course.
CASE REPORT
METHODS
A five-year-old boy without remarkable family history was born with marked general muscle hypotonia and weakness, respiratory insufficiency, anomalies, and multiple joint contractures. Congenital myopathy was suspected based upon type 1 fiber predominance on muscle biopsy. However, he was diagnosed with CMS at age 4 years when his ptosis and ophthalmoplegia were found to be improved by edrophonium chloride and repetitive nerve stimulation showed attenuation of compound muscle action potentials. An exome sequencing identified a compound heterozygous missense variant of c.737C > T (p.A246V) and a novel intronic insertion c.1166 + 4_1166 + 5insAAGCCCACCAC in RAPSN. RT-PCR analysis which showed the skipping of exon 7 in a skeletal muscle sample confirmed that the intronic insertion was pathogenic. His myasthenic symptoms were remarkably improved by pyridostigmine.
CONCLUSION
CONCLUSIONS
The patient's diagnosis of CMS was confirmed by exome sequencing, and RT-PCR revealed that the skipping of exon 7 in RAPSN was caused by a novel intronic insertion. The genetic information uncovered in this case should therefore be added to the collection of tools for diagnosing and treating CMS.
Identifiants
pubmed: 34565654
pii: S0387-7604(21)00160-1
doi: 10.1016/j.braindev.2021.09.001
pii:
doi:
Substances chimiques
Muscle Proteins
0
peripheral membrane protein 43K
0
Types de publication
Case Reports
Langues
eng
Sous-ensembles de citation
IM
Pagination
50-55Informations de copyright
Copyright © 2021 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.
Déclaration de conflit d'intérêts
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.