Central core myopathy

Central core myopathy (CCM) is a congenital myopathy characterized by muscle weakness and low muscle tone. It is a rare genetic disorder that primarily affects the skeletal muscles, which are used for movement. The condition is named for the characteristic changes seen in muscle cells, specifically the presence of a central core that lacks the normal cellular structures.

Etiology

CCM is caused by mutations in the RYR1 gene, which provides instructions for making a protein that plays a key role in muscles used for movement (skeletal muscles). The RYR1 protein is part of a channel that releases calcium ions from storage within cells, an essential step in muscle contraction. Mutations in the RYR1 gene alter the structure or function of these channels, impairing their ability to regulate calcium ion flow and leading to the muscle weakness and other features of CCM.

Symptoms

The symptoms of CCM typically appear in infancy or early childhood, although they can also develop later in life. They include muscle weakness, low muscle tone (hypotonia), and delays in motor skills such as sitting, standing, and walking. Some individuals with CCM may also have skeletal abnormalities such as scoliosis (curvature of the spine) or hip dislocation.

Diagnosis

Diagnosis of CCM is based on the clinical symptoms, a physical examination, and specialized tests. These tests may include a muscle biopsy, which can reveal the characteristic central cores in muscle cells, and genetic testing, which can identify mutations in the RYR1 gene.

Treatment

There is currently no cure for CCM, and treatment is symptomatic and supportive. Physical therapy and occupational therapy may be beneficial for improving muscle strength and mobility. Surgery may be necessary to treat skeletal abnormalities such as scoliosis.

Prognosis

The prognosis for individuals with CCM varies. Some individuals have mild symptoms and normal life expectancy, while others may experience severe muscle weakness and related complications.

See also

• Congenital myopathies
• RYR1-related myopathies
• Muscular dystrophy