Congenital myopathies are rare muscle diseases mostly present at birth (congenital) that result from genetic defects. There are many different types of congenital myopathies, but most share common features, including lack of muscle tone and weakness.
Other signs and symptoms of some congenital myopathies include feeding and breathing difficulties, as well as skeletal conditions, such as curvature of the spine (scoliosis), weak bones (osteopenia) or hip problems. Signs and symptoms of congenital myopathies may not be apparent until later in infancy or childhood.
There are no known cures for congenital myopathies. However, the recent advances in gene therapy can provide treatment for congenital myopathies. The supportive treatments, including physical, occupational and speech therapies, nutritional support, and assisted breathing, may be helpful. Genetic counseling may help assess the risk of congenital myopathies in future pregnancies.
Signs and symptoms vary depending on the type of congenital myopathy. The severity of signs and symptoms also varies, though the conditions are often stable or slowly progressing.
Common signs and symptoms include:
- Lack of muscle tone
- Muscle weakness
- Delayed motor skills
- Noticeable facial weakness
- Drooping eyelids
- Muscle cramps or contractions
There are different types of congenital myopathies, some of which include:
- Central core disease. This condition causes muscle weakness and developmental problems. Some people may develop a significant reaction to general anesthesia (malignant hyperthermia).
- Centronuclear myopathies. These rare conditions cause muscle weakness in the face, arms, legs and eye muscles, and breathing problems.
- Congenital fiber type disproportion myopathy. Small fibers are found on muscle tissue during a biopsy. This condition causes muscle weakness in the face, neck, arms, legs and trunk.
- Nemaline myopathy. Nemaline myopathy is one of the more common congenital myopathies and causes muscle weakness in the face, neck, arms and legs, and sometimes scoliosis. It may also cause breathing and feeding problems.
- Multiminicore disease. This condition has several subtypes and often causes severe muscle weakness in the arms and legs, and scoliosis.
- Myotubular myopathy. This rare condition, which occurs only in males, causes muscle weakness, floppiness and breathing problems.
- Other myopathies. Other rare myopathies include autophagic vacuolar myopathy, cap disease, congenital myopathy with arrest of myogenesis, myosin storage (hyaline body) myopathy and zebra body myopathy.
When to see a doctor
Congenital myopathies are usually noticed at birth. But if you notice a lack of muscle tone or delayed motor skills as your baby grows, let your child's doctor know about your concerns.
Congenital myopathies are caused by one or more genetic abnormalities in genes that control muscle development.
The only known risk factor for congenital myopathies is having a blood relative with one of these conditions, or one or both parents who carry a mutated gene that causes them.
Congenital myopathies are associated with a number of complications, such as:
- Delays in motor skills
- Respiratory failure
- Feeding problems
There's no way to prevent congenital myopathies. If you're at high risk of having a child with a congenital myopathy, you may want to consult a genetic counselor before becoming pregnant.
A genetic counselor can help you understand your chances of having a child with a congenital myopathy. He or she can also explain the prenatal tests that are available and help explain the pros and cons of testing.