A centronuclear myopathy is one of a number of myopathies, or muscle disorders, in which the nuclei of muscle cells are located at the center of the cell instead of at their normal location at the outer edge of the cell. Centronuclear myopathy is a congenital disorder, meaning that it results from problems or defects in fetal development that may or may not be genetic in nature. Though it is considered to be a congenital disorder, rare cases do appear in people later in life. The genetic traits of the disorder cause it to be most commonly expressed in male infants.
The two main symptoms of centronuclear myopathy are hypotonia and hypoxia. In hypotonia, an individual has particularly low muscle tone which tends to lead to a lack of muscular strength. Hypoxia is a condition in which an individual's body receives an inadequate supply of oxygen. Another indicator of centronuclear myopathy is scaphocephaly, a condition in which one is born with a long, narrow head. Hypoxia is the most serious of these symptoms as infant death can sometimes occur if assisted breathing is not administered in time.
A genetic abnormality occurring on the x-chromosome is generally associated with centronuclear myopathy. The specific gene affected is referred to as MTM1; it is required for the proper differentiation of muscle cells. Mutations in MTM1 are believed to cause problems in muscular development. A strong correlation has, indeed, been observed between myopathy cases and MTM1 mutations.
Myotubular myopathy is by far the most common form of centronuclear myopathy; the two terms, in fact, are nearly interchangeable. Even though it is the most common, even myotubular myopathy is incredibly rare. Electrodiagnostic testing, which involves a series of techniques used to measure electrical nerve activity in muscles, is commonly used in the diagnosis of centronuclear myopathy and in other forms of myopathy. Unfortunately, many infants die of myotubular myopathy before they can be diagnosed or treated for the disorder.
To date, there is no known cure for centronuclear myopathy, though there are methods that allow those with the disorder to function reasonably well. Physical therapy is generally used to teach people how to function on their own as well as possible. Otherwise, treatment is almost strictly symptomatic. Lack of strength in the torso, for example, can lead to curvature of the spine, so people with myopathies often need to seek treatment for back problems such as scoliosis.