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Central core disease
This condition typically presents in infancy or early childhood with reduced muscle strength, delayed motor milestones, and skeletal abnormalities. The severity varies considerably between affected individuals, ranging from mild weakness to more significant mobility challenges.
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Overview
Central core disease is a congenital myopathy, meaning it is a muscle disorder present from birth that affects the structure and function of skeletal muscle fibres. The condition takes its name from the distinctive appearance of affected muscle cells when examined under a microscope, which show pale central regions lacking normal mitochondrial activity within the muscle fibres. These 'cores' represent areas where the internal structure of the muscle cell is disrupted.
The condition is rare, though exact UK prevalence is unknown. Most individuals with central core disease experience symptoms from infancy or early childhood, though the degree of muscle weakness and associated features can differ substantially even within the same family. Some people maintain good functional ability throughout life, whilst others require mobility aids or assistive devices.
Symptoms & clinical features
The hallmark feature of central core disease is generalised muscle weakness, which tends to affect the muscles closest to the body's centre (proximal muscles) more than those in the hands and feet. Infants may present with reduced muscle tone (hypotonia), sometimes described as 'floppiness', and may achieve motor milestones such as sitting, standing, and walking later than expected. Muscle weakness often remains relatively stable over time rather than progressively worsening, though this pattern varies between individuals.
Skeletal abnormalities frequently accompany the muscle weakness. These may include curvature of the spine (scoliosis), hip displacement, and foot deformities such as high-arched feet or club foot. Joint contractures, where reduced flexibility limits the range of movement, can develop in some affected individuals. Facial muscle weakness is generally mild or absent, distinguishing central core disease from some other congenital myopathies. Intelligence and cognitive development are typically unaffected.
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Affected organs
Central core disease primarily affects skeletal muscles throughout the body, particularly those of the trunk, hips, and thighs. The characteristic structural abnormality occurs within individual muscle fibres, where regions called cores show disorganised internal architecture and reduced oxidative enzyme activity. These changes impair the muscle's ability to contract efficiently and maintain strength.
The skeletal system is secondarily affected due to the underlying muscle weakness. Reduced muscle support can lead to progressive spinal curvature and joint abnormalities during growth and development. The condition does not typically affect cardiac muscle or smooth muscle in internal organs, nor does it impact intellectual function or sensory abilities.
Risks & severity
The severity of central core disease spans a broad spectrum. Some individuals experience only mild weakness with minimal functional impact, maintaining independent mobility and daily activities throughout adulthood. Others face more significant challenges, including early-onset scoliosis requiring surgical intervention, persistent motor difficulties, and reliance on wheelchairs or walking aids. Most affected individuals have non-progressive or slowly progressive weakness, meaning the condition typically does not deteriorate rapidly over time.
An important consideration for people with central core disease is susceptibility to malignant hyperthermia, a potentially life-threatening reaction to certain anaesthetic agents used during surgery. This reaction causes dangerous elevation of body temperature and muscle breakdown. Individuals with RYR1-related conditions should inform all healthcare providers of their diagnosis before any surgical procedure, as alternative anaesthetic protocols can be used safely.
Genetic causes
Central core disease results from pathogenic variants in the RYR1 gene, which encodes the ryanodine receptor 1 protein. Within muscle cells, this protein functions as a calcium channel that is essential for normal contraction. Nerve impulses that stimulate muscle fibres trigger ryanodine receptor 1 to discharge calcium from storage sites inside the cell, allowing contractile machinery to generate force.
When RYR1 carries pathogenic variants, calcium release becomes dysregulated, resulting in abnormal muscle fibre structure and compromised contraction. On muscle biopsy, the cores appear as zones depleted of mitochondria and other cellular components, reflecting disrupted calcium management. RYR1 is implicated in several muscle disorders and malignant hyperthermia susceptibility, with distinct variants producing different clinical presentations.
- RYR1 ryanodine receptor 1The RYR1 gene encodes ryanodine receptor 1, a protein critical for calcium release in skeletal muscle cells, playing a key role in muscle contraction and relaxation.
Inheritance pattern
Central core disease can follow either an autosomal dominant or autosomal recessive inheritance pattern, depending on the specific RYR1 variant involved. In autosomal dominant cases, inheriting one altered copy of RYR1 from an affected parent is sufficient to cause the condition, with a 50% chance of passing it to each child. In autosomal recessive cases, both gene copies must carry pathogenic variants for symptoms to develop. Parents of a child with recessive central core disease each possess one altered copy but typically show no symptoms themselves, as one functional gene copy is sufficient for normal muscle function. These carrier parents face a 25% chance with each pregnancy of having another affected child.
Other family members may also be carriers without knowing it. Genetic counselling can help families understand the inheritance pattern in their specific case, recurrence risk, and discuss testing options for relatives who may wish to know their carrier status, particularly when planning their own families.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
Diagnosis & testing
Diagnosis of central core disease typically begins with clinical evaluation of muscle weakness and associated skeletal features, followed by specialised muscle biopsy. The biopsy reveals the characteristic central cores within muscle fibres when examined with specific staining techniques. Genetic testing of the RYR1 gene confirms the diagnosis by identifying pathogenic variants, and is increasingly used as a first-line investigation given its non-invasive nature.
Within the NHS, patients with suspected congenital myopathy are usually referred to specialist neuromuscular or clinical genetics services. The condition is included in genetic testing panels for neuromuscular disorders accessed through the NHS Genomic Medicine Service. Families concerned about central core disease can be referred to their local clinical genetics service for assessment, genetic counselling, and access to appropriate testing pathways.
Management & lifestyle
Management of central core disease focuses on maintaining muscle strength and function, preventing complications, and monitoring for skeletal changes. Physiotherapy plays a central role, with tailored exercise programmes designed to preserve muscle function and joint flexibility without causing excessive fatigue. Occupational therapy can assist with adaptive strategies and equipment to support independence in daily activities.
Orthopaedic monitoring is important for early detection and management of scoliosis and joint contractures. Some individuals require bracing or surgical intervention for progressive spinal curvature. Given the association with malignant hyperthermia, all affected individuals should carry medical alert documentation and inform healthcare providers of their RYR1 status before any procedure requiring anaesthesia. Genetic counselling provides families with information about inheritance, recurrence risks, and testing options for relatives. NHS care is coordinated through specialist neuromuscular clinics in collaboration with local paediatric or adult neurology services.
UK care pathway
Within the NHS Genomic Medicine Service, central core disease falls under neuromuscular disorder testing pathways. Patients are typically referred to clinical genetics or specialist neuromuscular services by their GP or paediatrician when congenital myopathy is suspected. Genetic testing for RYR1 variants is available through NHS laboratories, often as part of broader gene panels for inherited muscle conditions.
Genetic counsellors within NHS clinical genetics departments provide detailed discussion of test results, inheritance patterns, and implications for family members. They can also facilitate carrier testing for at-risk relatives and discuss reproductive options. Ongoing clinical care involves multidisciplinary input from neurology, physiotherapy, orthopaedics, and anaesthetics as needed, coordinated through regional neuromuscular centres.
Frequently asked questions
Will my child's muscle weakness get worse over time?
Central core disease is typically non-progressive or very slowly progressive, meaning muscle weakness usually remains stable rather than deteriorating significantly. Many children maintain their functional abilities into adulthood, though monitoring for skeletal complications like scoliosis remains important throughout growth.
Is it safe for someone with central core disease to have surgery?
Surgery can be performed safely, but it requires special precautions due to the risk of malignant hyperthermia with certain anaesthetic drugs. Your anaesthetist should be informed of the RYR1 diagnosis beforehand so they can use alternative safe anaesthetic agents and monitoring protocols.
Can physiotherapy help with central core disease?
Physiotherapy is a key part of management and can help maintain muscle strength, prevent joint contractures, and support functional mobility. A physiotherapist experienced in neuromuscular conditions can design an individualised exercise programme appropriate to your or your child's abilities.
How is central core disease inherited in my family?
The inheritance pattern depends on the specific RYR1 variant. Some families have autosomal dominant inheritance where one affected parent has a 50% chance of passing the condition to each child, whilst others have autosomal recessive inheritance with different risks. A genetic counsellor can clarify the pattern in your specific case.
Could other family members be carriers without symptoms?
In families with recessive inheritance, siblings and other relatives of affected individuals may carry one altered RYR1 copy without showing any muscle weakness. Carrier testing through clinical genetics services can clarify this, which may be particularly relevant for relatives planning families.
References
- Robinson R, Carpenter D, Shaw MA. Mutations in RYR1 in malignant hyperthermia and central core disease. Human mutation. 2006. PMID: 16917943
- Kushnir A, Todd JJ, Witherspoon JW. Intracellular calcium leak as a therapeutic target for RYR1-related myopathies. Acta neuropathologica. 2020. PMID: 32236737
- Kaur H, Katyal N, Yelam A. Malignant Hyperthermia. Missouri medicine. 2019. PMID: 31040503
- Jungbluth H. Central core disease. Orphanet journal of rare diseases. 2007. PMID: 17504518
- Younger DS. Congenital myopathies. Handbook of clinical neurology. 2023. PMID: 37562885
- Amburgey K, Bailey A, Hwang JH. Genotype-phenotype correlations in recessive RYR1-related myopathies. Orphanet journal of rare diseases. 2013. PMID: 23919265
- Jungbluth H, Sewry CA, Muntoni F. Core myopathies. Seminars in pediatric neurology. 2011. PMID: 22172419
- Garibaldi M, Rendu J, Brocard J. 'Dusty core disease' (DuCD): expanding morphological spectrum of RYR1 recessive myopathies. Acta neuropathologica communications. 2019. PMID: 30611313