Hereditary myopathies

What is it about ?

The term “myopathies” covers a very large number of disorders of the muscles. Many of these conditions are hereditary. This means that parents pass them on to their children. Often the disease affects several members of the family. They are in fact neuromuscular diseases (MNM), the prefix “neuro” designating the nerves.

Duchenne’s disease is an example of severe hereditary myopathy. The affection mainly affects boys. The muscles gradually weaken, including those of the breathing and the heart. Most children find themselves in a wheelchair between the ages of 8 and 12, and typically need breathing assistance around the age of 20.

How to recognize them?

Symptoms may be:

• weakness of the muscles that worsens progressively
• a decrease in muscle mass,
• pain or cramps during activity
• sagging eyelids
• problems swallowing,
• problems speaking.

In newborns and infants, myopathy may be suspected in the following cases:

• he has difficulty holding his head upright,
• he moves less,
• he has trouble sucking effectively,
• he has trouble breathing well.

The child will also walk later than the others. Sometimes the hip joint is dislocated and joint contractures (= abnormal position of a joint) and deformity of the spine can occur. These abnormalities can be so severe that the child ends up in a wheelchair.

Symptoms in themselves are not sufficient to make the diagnosis. There are indeed many hereditary myopathies. Additional examinations will therefore always be necessary.

How is the diagnosis made?

In case of suspicion of hereditary myopathy, a whole series of examinations will be carried out in the hospital:

• a blood test;
• a muscle biopsy;
  • this test involves taking a small piece of muscle tissue and sending it to the laboratory for analysis.
• an electroneuromyogram (EMG);
  • this test measures the small electrical currents necessary for the normal functioning of nerves and muscles.
• a CT scan and an MRI;
  • these tests help to visualize the extent of the damage to the muscles.
• genetic or DNA analysis;
  • this is the most important exam,
  • who can identify problems in genes,
  • the analysis can be carried out not only at the small patient, but also at relatives.

What can you do ?

If there are cases in your family, ask (in consultation with the doctor) what disease it is exactly.

If you want to have children, discuss with the doctor the advisability of carrying out a DNA analysis beforehand.

If you have a child with hereditary myopathy, first of all try to maintain his independence as long as possible. This can go through an adapted medical gymnastics, under the supervision of a physiotherapist. Arrangements must sometimes be made to the home: doors wide enough for a wheelchair to pass, bypassing stairs, adapted bathroom, etc. The disease can also be accompanied by mental retardation requiring appropriate education.

What can your doctor do?

A specialist takes care of the treatment. Preferably in a specialized center, where a team can provide the necessary supervision.

Sources

Foreign clinical practice guide ‘Hereditary myopathies’ (2000), updated on 01.09.2017 and adapted to the Belgian context on 19.05.2019 – ebpnet