Myopathy is a medical disorder in which the muscle fibers in our body start malfunctioning resulting in a variety of symptoms.1 Some types of myopathies are congenital or inherited while some forms of myopathies present themselves later in life of an individual. In this article, we will discuss about a congenital myopathy called as Centronuclear Myopathy.
How Do We Define Centronuclear Myopathy (CNM)?
Centronuclear Myopathy is a group of congenital myopathies in which the cell nuclei becomes abnormally placed in the skeletal muscles of our body.2 In a healthy individual the cell nuclei is located in the periphery of the cell, but in cases of Centronuclear Myopathy the cell nuclei is located in the center of the cell. It presents itself with severe hypotonia, episodes of hypoxia resulting in breathing assistance. Among the various forms of Centronuclear Myopathies, X-linked myotubular myopathy generally presents itself at birth and is termed to be a congenital form of myopathy.
Causes of Centronuclear Myopathy (CNM)
- Centronuclear Myopathy is caused by mutations in DNM2 and BIN1 genes.1
- The DNM2 gene is responsible for providing instructions for making a type of protein called Dynamin-2, which is responsible for bringing substances into the cell.
- The BIN1 gene is responsible for providing instructions for making a protein which interacts with other proteins and has involvement in cell membrane structuring.
Symptoms of Centronuclear Myopathy (CNM)
As is the case with other forms of myopathies, clinical presentations of Centronuclear Myopathy are muscle weakness with related disabilities. Congenital forms of it presents with decreased neonatal muscle tone, acute weakness, developmental delays like delayed head control, ability to crawl and walk as well as respiratory problems as a result of weak respiratory muscles. Some of the other symptoms for Centronuclear Myopathy are high arched palate, abnormally elongated digits, bell-shaped chest, long face.
Diagnosis of Centronuclear Myopathy (CNM)
Generally, in cases of Centronuclear Myopathy the muscle biopsy will show the location of the cell in the center confirming it.
EMG can also help confirm Centronuclear Myopathy. The EMG study will show abnormal spontaneous activity on needle EMG with relatively small CMAP amplitudes.
Treatment for Centronuclear Myopathy (CNM)
At present, there is no clear cut cure for Centronuclear Myopathy. The main aim of treatment is to improve the functionality of the affected individual and minimize medical complexities. Physical therapy is also done to help with the weakness of the muscles. Pharmacotherapy is used for management of pulmonary complications that may arise due to weakened respiratory muscles. Weakness of the trunk muscles may result in development of scoliosis, so this also needs to be monitored, which may even require surgical correction.