Muscular Dystrophy

Muscular dystrophy (MD) is an inherited (genetic) disorder of the muscles. It is called a neuromuscular disease. There are several types. Becker muscular dystrophy (BMD) is a rare type. It usually has milder symptoms and occurs later than Duchenne muscular dystrophy (DMD), which is more common. BMD causes weakness of skeletal muscles, breathing muscles, and the heart muscle. Over time, the muscle fibers break down. Although skeletal muscle involvement is generally less severe than in DMD, heart involvement is often more of a problem with BMD.

Gender words are used here to talk about anatomy and health risk. Please use this information in a way that works best for you and your doctor as you talk about your child's care.

Causes of Becker Muscular Dystrophy

BMD is a genetic disease. This means it passes from parents to children. It is caused by a faulty gene on the X chromosome. It mostly affects boys. Girls are only carriers and usually don't have symptoms.

People normally have 23 pairs of chromosomes in each cell of their body. One set of 23 chromosomes comes from each parent. Each chromosome contains many genes. One of these pairs of chromosomes controls a person's sex. If this pair is two X chromosomes (XX), then the child is female. If this pair is one X and one Y chromosome (XY), then the child is male.

The faulty BMD gene is an X-linked recessive gene. This means the gene needs to be on each of a girl's two X chromosomes for symptoms of the disease to occur in her. She would need to inherit the faulty gene from both parents. If a girl has only one faulty gene on one X chromosome, she is a carrier of the disease but will likely not have symptoms. Boys have only one X chromosome, so if their X chromosome has a faulty gene, they will have symptoms.

Children Who Are at Risk for Becker Muscular Dystrophy

Children are more at risk for BMD if they have a family member with the disease. Girls are rarely affected by this type of muscular dystrophy.

Symptoms of Becker Muscular Dystrophy

Symptoms usually start during the teen or early adult years. They can include:

• Muscle cramping and feeling weak when exercising
• Trouble walking, running, jumping, or climbing stairs
• Falling often
• Muscle pain
• Enlarged calves
• Walking on tips of toes
• Weakness in arms and shoulders
• Tiredness
• Difficulty breathing, especially with heart involvement

The symptoms of BMD can be like other health conditions. Make sure your child sees their doctor for a diagnosis.

Diagnosing Becker Muscular Dystrophy

The doctor will ask about your child's symptoms and health history. They may also ask about your family's health history to find out if other family members have had muscular dystrophy. They will give your child a physical exam. Your child may also have tests, such as:

• Blood tests. These may include genetic blood tests. Some genetic tests can be done with saliva and don't need blood tests.
• Electromyogram (EMG) and nerve conduction studies. These tests check if muscle weakness is a result of muscle or nerve damage.
• Muscle biopsy. A small sample of muscle tissue is taken and looked at under a microscope.
• Electrocardiogram (ECG). This is a test that records the electrical activity of the heart. It shows abnormal rhythms (arrhythmias) and detects heart muscle damage.
• Echocardiogram. This is an ultrasound test of the heart muscle. It shows a picture of how strong the heart muscle is pumping.

Treating Becker Muscular Dystrophy

Treatment will depend on your child's symptoms, age, and general health. It will also depend on how severe the condition is.

There is no known cure for BMD or treatment to stop the muscles from weakening. The goal of treatment is to keep muscles as strong as possible to allow a child to function independently. Treatment almost always includes several kinds of specialists. It also includes testing over time, such as imaging, EMG, and heart and pulmonary studies.

Treatment choices include:

• Physical therapy to strengthen muscle and help prevent muscle contractures
• Braces and splints
• The use of steroid medicines, though they can have unwanted side effects
• Surgery to treat contractures
• Medicines for heart disease, bone disease, and respiratory disease when they occur
• Medicines from clinical research trials
• Wheelchair use
• Nutritional counseling
• Psychological counseling

Talk with your child's health care providers about the risks, benefits, and possible side effects of all treatments.

Possible Complications of Becker Muscular Dystrophy

Children with BMD may have additional health problems, such as:

• Heart muscle weakening and not pumping blood well (dilated cardiomyopathy)
• Breathing and lung problems
• Scoliosis, a sideways curving of the back bones (vertebrae)
• Diet, nutrition, and digestive problems
• Trouble focusing, learning, or controlling emotions
• Complications from anesthesia, for which special care is needed

How to Help Prevent Becker Muscular Dystrophy in Your Child

Your doctor may advise genetic counseling. You can discuss with a counselor the risk for BMD in a future pregnancy.

How to Help Your Child Live With Becker Muscular Dystrophy

BMD is a condition that gets worse over time (progressive). It needs lifelong management. Walking and sitting often become more difficult as a child grows. In time, some will eventually need a wheelchair. This is because the leg muscles become too weak to work. Often, those with BMD can continue to walk for many years. In some cases, a child may need a wheelchair earlier.

Your child will also need a heart imaging test every 1 to 2 years. This may be a heart echocardiogram or MRI. These tests look at the function and health of the heart. A child with BMD will need special care during surgery to prevent problems from anesthesia.

People with BMD usually live until their 40s. Problems from cardiomyopathy are a common cause of death.

A care team will work with your family to improve your child's function and give support as you learn to care for your child's needs.

You can contact the Muscular Dystrophy Association for support, resources, and help.