Overview

Congenital myopathies are rare muscle diseases 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. Supportive treatments include physical, occupational and speech therapies, nutritional support, and assisted breathing, if needed. Genetic counseling may help assess the risk of congenital myopathies in future pregnancies.

Congenital myopathy care at Mayo Clinic

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Symptoms

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

Types of congenital myopathies 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 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 your concerns.

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Causes

Congenital myopathies are caused by one or more genetic abnormalities in genes that control muscle development.

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Diagnosis

To diagnose the condition, your doctor will review your medical and family history. He or she will conduct a physical and a neurological examination to find the cause of the muscle weakness and rule out other conditions. Your doctor may conduct several tests to diagnose congenital myopathy.

• Blood tests may be ordered to detect an enzyme called creatine kinase.
• Electrocardiogram (ECG). An electrocardiogram may be conducted to observe your heart's electrical activity.
• Electromyography (EMG). Electromyography measures electrical activity within muscles.
• Genetic testing may be recommended to verify a particular mutation.
• Muscle biopsy. A specialist may remove and examine a small sample of tissue (biopsy) from your muscle.

Prenatal diagnosis

If you have a known family history of congenital myopathies, you can opt for minimally invasive prenatal testing. Chorionic villus sampling can be done after 11 weeks of pregnancy. Amniocentesis can be done after 15 weeks, and cordocentesis can be done shortly after that.

The risk of pregnancy loss associated with these tests is less than 1 percent.

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Complications

Congenital myopathies are associated with a number of complications, such as:

• Delays in motor skills
• Scoliosis
• Pneumonia
• Respiratory failure
• Feeding problems
• Death

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Prevention

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.

Coping and support

When you learn your child has a congenital myopathy, you may experience a range of emotions, including anger, fear, worry, sorrow and guilt. You may not know what to expect, and you may worry about your ability to care for your child. The best antidote for fear and worry is information and support.

Consider these steps to prepare yourself and to care for your child:

• Find a team of trusted professionals. You'll need to make important decisions about your child's education and treatment. Build a team of health care providers, teachers and therapists you trust. These professionals can help evaluate the resources in your area and explain state and federal programs for children with disabilities.
• Seek out other families who are dealing with the same issues. Ask your doctor if your community has a support groups for parents of children with congenital myopathies. You can also find internet support groups. Family and friends also can be a source of understanding and support.

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Risk factors

Possible risk factors for congenital myopathies include:

• Infections
• Foreign travel
• Medications, such as cholesterol-lowering statins
• Alcohol abuse

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