Central core disease

Central core disease is an inherited disorder of the skeletal muscles, the muscles used for movement. It causes muscle weakness that ranges from barely noticeable to very severe, and the severity can differ even among affected members of the same family. Most people have persistent, mild weakness that does not worsen with time, mainly in the proximal muscles near the center of the body such as those of the shoulders, upper legs and hips. Weakness in infants can delay sitting, standing and walking, although most people walk independently. Other features can include muscle pain or exercise intolerance, strabismus, kyphoscoliosis, foot deformities, hip dislocation and joint contractures; in severe cases infants have facial weakness, profound low muscle tone and life-threatening breathing problems. Many people with the condition have an increased risk of malignant hyperthermia, a severe reaction to some anesthetic gases and muscle relaxants. The name comes from disorganized areas called central cores seen under the microscope in muscle cells, and how they relate to the weakness is unclear. The exact prevalence is unknown, but it is thought to be the most common congenital myopathy. Mutations in the RYR1 gene, which encodes ryanodine receptor 1, a calcium channel in muscle cells, cause the disease. It is most often inherited in an autosomal dominant pattern and less commonly in an autosomal recessive pattern. It is also known as central core myopathy, Shy-Magee syndrome and Shy's disease.