What Is NEB-Related Nemaline Myopathy?
Nemaline myopathy is a genetic disease that causes muscle weakness in the face, neck, trunk, upper arms, and upper legs (that is, the muscles that are closest to the center of the body). This typically results in complications related to walking, speaking, swallowing, and breathing. There are at least six different forms of nemaline myopathy that have been described, each defined based on the age at which symptoms begin and the severity of the disease. The condition may also be caused by mutations in several different genes.
NEB-related nemaline myopathy is caused by mutations in the NEB gene and is most often associated with "typical" or "typical congenital" nemaline myopathy. Individuals with typical nemaline myopathy are usually born with the muscle weakness that is characteristic of the disease. They experience a delay in motor development, but most are eventually able to walk independently and lead active lives. They may have speech or swallowing difficulties, and respiratory problems are possible. Less commonly, individuals with NEB-related myopathy have a more severe form of the condition. In this case, the risk of respiratory complications is higher and is associated with a shortened lifespan. In addition, problems with mobility are more severe and may include the presence of multiple joint contractures at birth (where there is an inability to straighten the affected joints).
How Common Is NEB-Related Nemaline Myopathy?
The estimated prevalence of NEB-related nemaline myopathy is 1 in 30,000 individuals. NEB-related nemaline myopathy has also been estimated to account for up to 50% of all nemaline myopathy cases.
How Is NEB-Related Nemaline Myopathy Treated?
There is no treatment or cure for the underlying cause of nemaline myopathy. Available treatments address only the symptoms of the disease. Physical therapy may significantly improve mobility and strength, and assistive devices may benefit some individuals. In addition, speech therapy may help those who have speech-related difficulties. It is also important to monitor all individuals with nemaline myopathy for problems with swallowing and breathing, and all respiratory infections should be treated promptly and aggressively. In cases with severe disease, a feeding tube and mechanical breathing support may be necessary.
What Is the Prognosis for an Individual with NEB-Related Nemaline Myopathy?
Individuals with typical nemaline myopathy, the form most often associated with NEB gene mutations, tend to have a good overall prognosis. Most are able to walk independently and have relatively active lives. However, those with more severe forms of nemaline myopathy may experience recurrent lung infections and respiratory failure, which can lead to death in early childhood.