Becker muscular dystrophy (BMD)

What happens in this disease?

The disease is caused by a change in the DMD gene. This gene makes a protein called dystrophin, which protects the muscle fibers. In the Becker type, there is too little of this protein or it does not work fully. As a result, the skeletal muscles and the heart muscle are damaged over time.

Which symptoms can occur?

Symptoms often begin between the ages of 5 and 15, but they can also appear later. The course varies from person to person.

• Slowly increasing weakness in the leg and hip muscles
• Frequent falls, difficulty climbing stairs and getting up from the floor
• Difficulty running and jumping
• Walking on tiptoe
• Weakening of the heart muscle, called cardiomyopathy
• Curvature of the spine, called scoliosis
• Tiredness and difficulty breathing

How is it diagnosed?

The doctor examines the muscles and nerves. CK, a muscle enzyme, is measured in the blood. The diagnosis is confirmed with a genetic test that looks at the DMD gene. If needed, a muscle biopsy, EMG and heart tests are done.

Treatment and care

There is not yet a treatment that cures the disease; new treatments are being researched. Care aims to control symptoms and protect quality of life. Staying active is recommended; long periods without movement can weaken the muscles. Physiotherapy helps maintain muscle strength. Mobility aids and a wheelchair make getting around easier. The heart is checked regularly; if needed, devices such as a pacemaker are fitted. Some doctors may recommend steroid treatment. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through X-linked recessive inheritance. This is why mostly boys are affected. An affected boy usually inherits the gene from his carrier mother. Sometimes the change appears for the first time in the child and does not come from the family. The daughters of an affected father will very likely carry the gene. Women who are carriers may have a risk of mild muscle weakness and heart problems. Genetic counselling helps the family understand the risk.