CC BY-NC-ND 4.0 · Ibnosina Journal of Medicine and Biomedical Sciences 2024; 16(02): 077-084
DOI: 10.1055/s-0043-1778047
Case Report

Congenital Myopathy-1B due to RYR 1 Gene Mutation in Three Libyan Families

Samira Etarhuni
1   Department of Pediatric Neurology, Faculty of Medicine, University of Tripoli, Tripoli, Libya
2   Department of Neuropediatric, Tripoli University, Tripoli Children Hospital, Tripoli, Libya
Nadia Alghazir
3   Department of Pediatric Endocrine, Tripoli University, Tripoli University Hospital, Tripoli, Libya
› Author Affiliations
Funding None.


Introduction We report a series of patients in three different Libyan families diagnosed with congenital myopathy to study the wide clinical variability between these families, and the genetic heterogeneity.

Description of Cases We describe six patients, one patient presented with severe neonatal-onset RYR1-associated myopathy while the other five patients came mainly due to delay in motor development; genetic testing confirmed the diagnosis of CMY-1B disease due to RYR1 mutation in all patients. Clinical features of congenital widely varied between the families ranging from profound hypotonia during the neonatal period in one family to a motor delay and abnormal gait during childhood in other two families. Whereas the clinical picture is quite similar in the patients of same family, the patient who presented with severe neonatal presentation of RYR1-associated myopathy also had gastrostomy feeding, respiratory involvement, clubfeet, cleft palate, and undescended testes. The five patients who presented due to delay in motor development all were ambulatory without the need of support, except the youngest one aged 4 years still walking with support. The genetic study in the form of whole-exon sequencing as well as next-generation sequencing showed homozygosity of a gene mutation in five patients and a compound heterozygosity in one patient which presented with neonatal severe hypotonia.

Conclusion CMY-1B disease is a rare autosomal dominant and recessive genetic disorder that has variable clinical presentations. The early diagnosis is very important for genetic counseling as well as avoiding malignant hyperthermia. We also report rare and unusual presentations that may further delay the diagnosis.

Compliance with Ethical Principles

Prior ethical approval is not required for single cases and small case series. All patients or guardians consented for participation provided idendity is not revealed.

Publication History

Article published online:
06 June 2024

© 2024. The Libyan Biotechnology Research Center. 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 commercial purposes, or adapted, remixed, transformed or built upon. (

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