Central core disease

Central Core Disease
File:Cell sample of muscle tissue with central core disease (stained for contrast).jpg
Synonyms	Central core myopathy
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Central core disease (CCD), also known as central core myopathy, is an autosomal dominantly inherited<ref name=ryr>,

 RYR1 mutations causing central core disease are associated with more severe malignant hyperthermia in vitro contracture test phenotypes, 
 Human Mutation, 
 
 Vol. 20(Issue: 2),
 pp. 88–97,
 DOI: 10.1002/humu.10098,
 PMID: 12124989,</ref> muscle disorder present from birth that negatively affects the skeletal muscles. It was first described by Shy and Magee in 1956.<ref name=Quinlivan>Quinlivan RM, 
 Central core disease: clinical, pathological, and genetic features, 
 Arch. Dis. Child., 
 2003,
 Vol. 88(Issue: 12),
 pp. 1051–5,
 DOI: 10.1136/adc.88.12.1051,
 PMID: 14670767,
 PMC: 1719384,
 
 Full text,</ref><ref>, 
 A new congenital non-progressive myopathy, 
 Brain, 
 1956,
 Vol. 79(Issue: 4),
 pp. 610–21,
 DOI: 10.1093/brain/79.4.610,
 PMID: 13396066,</ref> It is characterized by the appearance of the myofibril under the microscope.<ref>"central core disease" at Dorland's Medical Dictionary

</ref>

Signs and symptoms

The symptoms of CCD are variable, but usually involve hypotonia (decreased muscle tone) at birth, mild delay in child development (highly variable between cases), weakness of the facial muscles, and skeletal malformations such as scoliosis and hip dislocation.<ref name=Quinlivan/>

CCD is usually diagnosed in infancy or childhood, but some patients remain asymptomatic until adulthood to middle age.<ref>,

 Adult central core disease. Clinical, histologic and genetic aspects: case report and review of the literature., 
 Clin Neuropathol, 
 
 Vol. 25(Issue: 4),
 pp. 180-4,
 
 PMID: 16866299,</ref> While generally not progressive, there appears to be a growing number of people who do experience a slow clinically significant progression of symptomatology. These cases may be due to the large number of mutations of ryanodine receptor malfunction, and with continued research may be found to be clinical variants.

^{(June 2012)}

Pathophysiology

Central core disease has an autosomal dominant pattern of inheritance.

Central core disease is inherited in an autosomal dominant fashion. Most cases have demonstrable mutations in the ryanodine receptor type 1 (RYR1) gene,<ref name=ryr/> which are often de novo (newly developed). People with CCD are at increased risk for developing malignant hyperthermia (MH) when receiving general anesthesia.<ref name=Quinlivan/>

Diagnosis

The diagnosis is made based on the combination of typical symptoms and the appearance on biopsy (tissue sample) from muscle. The name derives from the typical appearance of the biopsy on light microscopy, where the muscle cells have cores that are devoid of mitochondria and specific enzymes.<ref name=Quinlivan/>

Respiratory insufficiency develops in a small proportion of cases. Creatine kinase tend to be normal and electromyography (EMG) shows short duration, short amplitude motor unit action potentials.<ref name=Quinlivan/>

Treatment

There is no specific treatment but triggering anesthetics are avoided and relatives are screened for RYR1 mutations as these may make them susceptible to MH.<ref name=Quinlivan/>

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