Page 165 - GPD-4-1

Gene & Protein in Disease

CASE REPORT
Congenital myopathy-1B caused by a

homozygous RYR1 variant: A case report

1
Nagehan Bilgeç * , Saliha Yavuz Eravcı , Ahmet Sami Güven ,
2
2
and Hüseyin Çaksen 1
1 Department of Pediatric Genetics, Faculty of Medicine, Necmettin Erbakan University, Konya,
Turkey
2 Department of Pediatric Neurology, Faculty of Medicine, Necmettin Erbakan University, Konya,
Turkey

Abstract

Congenital myopathies are a group of clinically and genetically diverse neuromuscular
diseases that often present with stable and/or slowly progressive trunk and proximal
weakness. Genetic analysis can help diagnose each congenital myopathy more
accurately. Although an increasing number of other causative genes have been
reported, ryanodine receptor 1 (RYR1)-related myopathy is the most common cause.
Herein, we report the clinical presentation of a patient with congenital myopathy-1B
(multiminicore disease) that was caused by a c.115 G>A homozygous variant of
RYR1. The patient had normal cognitive abilities but was developmentally delayed
and unable to walk. Electromyography revealed myogenic changes. The c.115G>A
variant located in the second exon of RYR1 was found to be homozygous in the
*Corresponding author: congenital neuromuscular gene panel. The patient’s parents and sister both carried
Nagehan Bilgeç the heterozygous variant. Clinical differences between family members with the
(drnkbilgec@gmail.com) homozygous and heterozygous variants of RYR1 highlight the correlation between
Citation: Bilgeç N, Eravcı SY, the genotype and phenotype.
Güven AS, Çaksen H. Congenital
myopathy-1B caused by a
homozygous RYR1 variant: Keywords: Congenital myopathy-1B; Ryanodine receptor 1-related variants;
A case report. Gene Protein Dis.
2025;4(1):4748. Multiminicore disease
doi: 10.36922/gpd.4748
Received: September 3, 2024
Revised: November 9, 2024
Accepted: November 12, 2024 1. Introduction
Published online: December 27,
2024 Congenital myopathies are a group of clinically and genetically diverse
neuromuscular diseases that often present with stable and/or slowly progressive
Copyright: © 2024 Author(s).
This is an Open-Access article trunk and proximal weakness. Limb deformities, hypotonia, respiratory distress at
distributed under the terms of the birth, delayed motor development, scoliosis, periodic muscle stiffness, and paralysis
Creative Commons Attribution are observed later in life. Although ryanodine receptor 1-related (RYR1) myopathy
License, permitting distribution,
and reproduction in any medium, is the most prevalent form of core myopathy, several other causative genes have been
1
provided the original work is reported. Pathogenic variants in RYR1 are associated with dominantly inherited
properly cited. congenital myopathy 1A, along with susceptibility to malignant hyperthermia (MH)
2
Publisher’s Note: AccScience (central core disease [CCD]; MIM 117000), King–Denborough syndrome (MIM
Publishing remains neutral with 619542), MH susceptibility 1 (MIM 145600), and recessively inherited congenital
4
3
regard to jurisdictional claims in 5
published maps and institutional myopathy-1B (CMYO1B; multiminicore disease; MIM 255320). Multiminicore
5
affiliations. disease is caused by a homozygous or compound heterozygous mutation in RYR1
Volume 4 Issue 1 (2025) 1 doi: 10.36922/gpd.4748