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RYR1
ryanodine receptor 1
RYR1 is located on the long (q) arm of chromosome 19, at band 19q13.2. Arm ratio per GRCh38 - banding schematic.
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Overview
RYR1 is located on chromosome 19q13.2 and encodes a calcium-release channel essential for excitation-contraction coupling in skeletal muscle. The gene is clinically significant in pharmacogenomics, as inherited variants can predispose individuals to life-threatening reactions during anaesthesia, a condition known as malignant hyperthermia susceptibility. Beyond this acute risk, pathogenic changes in RYR1 are also associated with several congenital myopathies characterised by muscle weakness and structural abnormalities in muscle fibres.
RYR1-related conditions follow autosomal dominant inheritance for malignant hyperthermia susceptibility and central core disease, whilst other myopathies may exhibit autosomal recessive patterns. The gene's dual role in pharmacogenomics and inherited muscle disorders has established it as a Tier 1-2 actionable gene in clinical genomics, with NHS panels routinely assessing RYR1 variants in multiple clinical contexts including anaesthetic risk stratification and congenital myopathy diagnosis.
What the gene does
The ryanodine receptor 1 protein functions as a calcium-release channel situated in the membrane of the sarcoplasmic reticulum, an intracellular compartment that stores calcium ions when skeletal muscles are at rest. During muscle activation, specific signals trigger the RYR1 channel to open, permitting stored calcium to flow rapidly into the surrounding cell fluid. This sudden increase in intracellular calcium concentration initiates the molecular events that cause muscle fibres to contract, a process termed excitation-contraction coupling.
The receptor responds to electrical signals transmitted along the muscle cell membrane, translating these electrical cues into the chemical signal of calcium release. Once muscle contraction is complete, calcium ions are actively transported back into the sarcoplasmic reticulum, allowing the muscle to relax. This cyclical release and reuptake of calcium underpins the coordinated contraction and relaxation essential for all voluntary movement. The RYR1 channel also interacts with regulatory proteins, including FKBP1A, which modulate its activity and ensure calcium release occurs in a controlled manner appropriate to the body's movement demands.
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Chromosome location
RYR1 is positioned on the long arm of chromosome 19 at cytogenetic band 19q13.2. The gene produces a protein of 5,038 amino acids, making ryanodine receptor 1 one of the largest known ion channels in human cells. Its substantial size reflects the complexity of its regulatory architecture and the multiple functional domains required to coordinate calcium release with remarkable temporal precision during muscle contraction.
Protein structure
The ryanodine receptor 1 protein comprises several distinct structural elements organised into a large macromolecular complex. The N-terminal region contains five MIR domains (MIR 1 through MIR 5, spanning amino acids 97-392), which are thought to contribute to protein-protein interactions and receptor assembly. Three B30.2/SPRY domains (B30.2/SPRY 1, 2, and 3) are distributed across the protein sequence, with B30.2/SPRY 1 located at amino acids 581-797, B30.2/SPRY 2 at 1,013-1,208, and B30.2/SPRY 3 at 1,356-1,570. A specific interaction region with FKBP1A lies at amino acids 669-680, enabling regulatory crosstalk with this binding protein.
The central portion of the receptor features approximately six repeating units (amino acids 841-2,959), including full-length repeats 1 and 2 and truncated repeat elements. A disordered region at amino acids 1,307-1,385 likely provides structural flexibility essential for conformational changes during channel gating. This complex domain organisation reflects the receptor's dual roles as both a calcium channel and a scaffold for multiple regulatory interactions.
Key variants
Over 100 pathogenic variants in RYR1 have been documented in association with muscle disorders and anaesthetic susceptibility. These genetic changes range from single amino acid substitutions to premature termination signals that produce shortened receptor proteins. Variants may either increase the sensitivity of the channel to activation signals, leading to excessive calcium release, or impair the receptor's ability to release calcium efficiently, resulting in muscle weakness. The functional consequences of individual variants can vary considerably, with some affecting predominantly anaesthetic response whilst others primarily manifest as congenital myopathy.
No pathogenic or likely-pathogenic ClinVar variants recorded yet for this gene.
Associated conditions
RYR1 variants are associated with a spectrum of skeletal muscle disorders and pharmacogenomic phenotypes. Malignant hyperthermia susceptibility represents the most acute clinical concern, characterised by life-threatening hyperthermia, muscle rigidity, and rhabdomyolysis triggered by volatile anaesthetics or depolarising muscle relaxants. Central core disease presents with proximal muscle weakness and cores visible on muscle biopsy, typically inherited in an autosomal dominant pattern. Congenital fibre-type disproportion myopathy causes generalised muscle weakness that usually remains stable over time, and may follow either autosomal dominant or autosomal recessive inheritance. Multi-minicore disease, typically autosomal recessive, features muscle weakness with multiple core-like areas on histological examination. The clinical presentation of RYR1-related myopathies can range from mild weakness detected only on examination to severe neonatal hypotonia requiring respiratory support.
Inheritance pattern
Conditions caused by pathogenic RYR1 variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
RYR1 holds green (high-evidence) status across multiple NHS Genomic Medicine Service panels, reflecting its well-established clinical utility. The gene appears on the Malignant hyperthermia panel (R371), where variant identification directly informs anaesthetic management decisions. It is also included in congenital muscle disorder panels such as Congenital myopathy (R81), Skeletal muscle channelopathy (R76), and Limb girdle muscular dystrophies, myofibrillar myopathies and distal myopathies (R82). Additional memberships include Acute rhabdomyolysis (R419), Arthrogryposis (R83), and Fetal anomalies (R21), underscoring the diverse presentations of RYR1-related conditions. This extensive panel coverage ensures that RYR1 variants are systematically evaluated in relevant clinical scenarios across paediatric and adult medicine within the NHS.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What is malignant hyperthermia and how does RYR1 relate to it?
Malignant hyperthermia is a severe, potentially fatal reaction to certain anaesthetic drugs characterised by high fever, muscle rigidity, rapid heart rate, and muscle breakdown. RYR1 variants are the most common genetic cause, as altered receptor function leads to uncontrolled calcium release in muscle cells when exposed to triggering anaesthetics. Individuals with known RYR1 variants can be safely anaesthetised using alternative agents.
Are all RYR1 variants associated with both muscle weakness and anaesthetic risk?
Not necessarily. Some RYR1 variants predominantly cause malignant hyperthermia susceptibility without significant baseline muscle weakness, whilst others primarily manifest as congenital myopathy with variable anaesthetic risk. The specific variant and its functional effect determine the clinical phenotype, and genetic counselling can help clarify individual risks.
How are RYR1-related conditions inherited?
Malignant hyperthermia susceptibility and central core disease typically follow autosomal dominant inheritance, meaning a single altered copy of RYR1 can cause the condition. Other RYR1-related myopathies may be autosomal recessive, requiring variants in both gene copies. Inheritance pattern depends on the specific condition and variant involved.
References
- Riazi S, Kraeva N, Hopkins PM. Malignant Hyperthermia in the Post-Genomics Era: New Perspectives on an Old Concept. Anesthesiology. 2018. PMID: 28902675
- Amburgey K, Bailey A, Hwang JH. Genotype-phenotype correlations in recessive RYR1-related myopathies. Orphanet journal of rare diseases. 2013. PMID: 23919265
- Clarke NF, Waddell LB, Cooper ST. Recessive mutations in RYR1 are a common cause of congenital fiber type disproportion. Human mutation. 2010. PMID: 20583297
- Lyfenko AD, Ducreux S, Wang Y. Two central core disease (CCD) deletions in the C-terminal region of RYR1 alter muscle excitation-contraction (EC) coupling by distinct mechanisms. Human mutation. 2007. PMID: 16958053
- Zorzato F, Jungbluth H, Zhou H. Functional effects of mutations identified in patients with multiminicore disease. IUBMB life. 2007. PMID: 17365175
- Zhou H, Jungbluth H, Sewry CA. Molecular mechanisms and phenotypic variation in RYR1-related congenital myopathies. Brain : a journal of neurology. 2007. PMID: 17483490
- Jungbluth H. Central core disease. Orphanet journal of rare diseases. 2007. PMID: 17504518
- Jungbluth H. Multi-minicore Disease. Orphanet journal of rare diseases. 2007. PMID: 17631035
- Rossi AE, Dirksen RT. Sarcoplasmic reticulum: the dynamic calcium governor of muscle. Muscle & nerve. 2006. PMID: 16477617
- Wu S, Ibarra MC, Malicdan MC. Central core disease is due to RYR1 mutations in more than 90% of patients. Brain : a journal of neurology. 2006. PMID: 16621918
- Robinson R, Carpenter D, Shaw MA. Mutations in RYR1 in malignant hyperthermia and central core disease. Human mutation. 2006. PMID: 16917943
- Avila G. Intracellular Ca2+ dynamics in malignant hyperthermia and central core disease: established concepts, new cellular mechanisms involved. Cell calcium. 2005. PMID: 15589992
- Treves S, Anderson AA, Ducreux S. Ryanodine receptor 1 mutations, dysregulation of calcium homeostasis and neuromuscular disorders. Neuromuscular disorders : NMD. 2005. PMID: 16084090
- Lyfenko AD, Goonasekera SA, Dirksen RT. Dynamic alterations in myoplasmic Ca2+ in malignant hyperthermia and central core disease. Biochemical and biophysical research communications. 2004. PMID: 15336973
- Adam MP, Bick S, Mirzaa GM. Nonsyndromic Malignant Hyperthermia Susceptibility. 1993. PMID: 20301325