Central core disease

Central core disease (CCD), also known as central core myopathy, is an autosomal dominant congenital myopathy (inborn muscle disorder). It was first described by Shy and Magee in 1956. It is characterized by the appearance of the myofibril under the microscope.

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.

Diagnosis
The diagnosis is made 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.

Respiratory insufficiency develops in a small proportion of cases. Creatine kinase and electromyography (EMG) tend to be normal.

Pathophysiology


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

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.