Navigating Becker Muscular Dystrophy: Symptoms, Diagnosis, and Treatment Options

This blog is designed to provide information about Becker Muscular Dystrophy for those living with this condition, their caregivers, loved ones, and anyone interested in learning about this disease. Here, you’ll find information about what Becker Muscular Dystrophy is, how it is diagnosed, the symptoms, and current treatments.

What is Becker Muscular Dystrophy?

Becker Muscular Dystrophy (BMD) is a condition that affects the muscles, causing them to become weaker and deteriorate over time. ¹ It belongs to a group of muscle disorders called dystrophinopathies, which also includes Duchenne Muscular Dystrophy (DMD).²

Becker Muscular Dystrophy is a rare condition, occurring in approximately 3 to 6 out of every 100,000 births, with boys being the most commonly affected. ¹

What causes Becker Muscular Dystrophy?

Becker Muscular Dystrophy is a hereditary disease caused by a mutation (changes in the DNA) within the dystrophin gene.^1,2 This gene is also mutated in Duchenne Muscular Dystrophy and is responsible for producing the dystrophin protein, which plays an important role in keeping muscle cells intact. It acts like a shock absorber in muscle cells, helping to protect muscle fibers from getting damaged during contractions, which are the tightening and shortening of muscles when they move or generate force. Without enough dystrophin, muscles gradually become damaged and weaker. ²

The dystrophin gene is one of the largest in our DNA and is located on the X chromosome. Becker Muscular Dystrophy affects mainly males due to how it is inherited. Males, who inherit one X chromosome from their mother and one Y chromosome from their father, will develop Becker Muscular Dystrophy if their X chromosome carries the mutation, as they lack a second X chromosome to compensate. Females have two X chromosomes, so if only one carries the mutation, the other usually provides enough dystrophin to prevent the disease. However, they can still pass the mutation on to their children (as “carriers”) and in very few cases, may experience symptoms of the disease.3

While both Becker and Duchenne Muscular Dystrophy result from mutations in the same dystrophin gene, the key difference lies in the type of dystrophin produced. In Duchenne Muscular Dystrophy, the body makes very little or none of this protein, leading to more severe muscle damage. However, in Becker Muscular Dystrophy, the body still makes some dystrophin – just in a shorter, less effective form – so muscle weakening happens more slowly and is generally less severe. ²

What are the symptoms?

The age when symptoms first appear can vary greatly. Typically, they appear between the ages of 5 and 15 years, though in some cases symptoms may not occur until adulthood. In addition, the speed of muscle deterioration varies significantly from one person to another. ^1,4

Muscle weakness in Becker Muscular Dystrophy usually starts in the hips, thighs, and shoulders. Calf muscles often become larger. As the muscles weaken, someone with Becker Muscular Dystrophy might walk with a waddling gait, walk on their toes, or stick out their abdomen. People with Becker Muscular Dystrophy might also find it hard to climb stairs, and walking may become more difficult over time. Other symptoms can include low tolerance for exercise, muscle pain or cramps, frequent falls, and feeling tired easily. As the condition progresses, some people may eventually need a wheelchair or a scooter to facilitate mobility. ^1,4

A lack of dystrophin can also weaken the muscle layer in the heart, leading to cardiomyopathy, a condition where the heart struggles to pump blood effectively.⁴ Respiratory muscles often stay strong for people with Becker Muscular Dystrophy for many years, but eventually, they may become weaker and lead to breathing or coughing difficulties. ⁴

Diagnosis of a Becker Muscular Dystrophy

To diagnose any type of muscular dystrophy, doctors often start by reviewing the patient’s family history and performing a physical examination. Family history can help determine the inheritance pattern of the disorder, while the physical examination may help determine which muscles are affected and how they are affected. ⁵

Physicians often also request to check a person’s blood to test for creatine kinase (CK), an enzyme that leaks out of damaged muscle. A high CK level suggests that the muscles are being harmed. However, the test does not show exactly what type of disorder may be causing it. ⁴ Additionally, other tests such as an electrocardiogram, and echocardiogram or a cardiac MRI may be performed to assess the heart’s function, as some people with Becker Muscular Dystrophy develop heart muscle weakness (cardiomyopathy). ⁵

A DNA test is also performed to see whether there is a mutation in the dystrophin gene, and if so, what type of mutation it is, and exactly where it occurs. This may help determine whether the condition is more likely to be Becker or Duchenne Muscular Dystrophy. In some cases, a doctor may suggest performing a muscle biopsy, where a small muscle sample is taken for examination to provide more information about the disease. However, this procedure is less frequent nowadays as most patients are diagnosed by genetic testing. ^5,6

Treatment for Becker Muscular Dystrophy

While there is no cure for this condition, the objective of Becker Muscular Dystrophy treatment is to help manage symptoms and improve quality of life.⁷ The approach to managing Becker Muscular Dystrophy is often similar to that used for milder cases of Duchenne Muscular Dystrophy.⁸ The treatment of Becker Muscular Dystrophy may include:

Physical exercise. Gentle exercise, such as swimming and water exercises, can help maintain muscle strength and keep the cardiovascular system healthy. However, it is important to first discuss with a doctor what exercises to perform and how much is appropriate, as too much exercise can cause muscle damage. ⁷

Physical therapy and orthopedic care. Muscle weakness in Becker muscular dystrophy can lead to scoliosis (curving of the spine) and joint contractures (tightening of muscles and joints), though this happens less often compared to Duchenne Muscular Dystrophy. Treatments may include gentle stretching exercises or using long leg braces to keep muscles and joints flexible, which can help delay the formation of contractures. In some cases, surgery may be needed to release contractures for people with more advanced symptoms. ^{7, 8} As the disease progresses, some people with Becker Muscular Dystrophy may need to use a wheelchair or scooter. ⁷

Nutrition. No special diet is typically required for people with Becker Muscular Dystrophy. However, excessive weight gain can become a problem for people who use power wheelchairs, take certain medications, or are not very active. For these people, calorie intake may be restricted to keep a healthy weight. ⁷ Individuals with Becker Muscular Dystrophy may also develop dysphagia (difficulty with swallowing) and may be referred to a speech and language therapist. ⁷

Cardiac care. Regular heart check-ups are essential for people with Becker Muscular Dystrophy, starting from an early age and continuing throughout life. While boys are more commonly affected, female carriers also face a higher-than-average risk of developing heart issues. Therefore, medical experts often recommend that both males who are affected and females who are carriers undergo regular monitoring. Cardiac transplantation may be offered as an option to patients with Becker Muscular Dystrophy with severe cardiomyopathy.⁷

Respiratory care. In some individuals with Becker Muscular Dystrophy, the breathing muscles may become weaker as they grow older, leading to less effective breathing, particularly during sleep.⁷ A bilevel positive airway pressure (BiPAP), a machine that helps breathing, may be recommended in these cases. ^7,9

Steroid drugs. Unlike in Duchenne Muscular Dystrophy, evidence of efficacy of steroid drugs, such as glucocorticoids, remains limited for treating Becker Muscular Dystrophy.¹⁰ However, the treating physician may consider them, for example in individuals with significant muscle weakness. ^7,8

Learning disabilities. Children with Becker Muscular Dystrophy who experience learning difficulties may be evaluated by a pediatric neuropsychologist. This specialist can suggest helpful exercises and strategies, and schools may provide extra assistance to support their learning. ⁷

Besides the supportive treatments for Becker Muscular Dystrophy, researchers are investigating new therapeutic approaches that aim to improve the disease progression, both in the laboratory and in clinical trials. Whilst historically investigational treatments have been focused on Duchenne Muscular Dystrophy, recent clinical research has increasingly focused on Becker Muscular Dystrophy making it a target for investigational trials.^7,11

If you want to know more about new investigational treatments for Duchenne Muscular Dystrophy, please visit this blog.

Conclusions

Becker Muscular Dystrophy is a condition that affects the muscles, causing them to become weaker and deteriorate over time. While there is no cure, various practices can help manage symptoms and improve the quality of life. These Becker Muscular Dystrophy treatment plans may include physical exercise, orthopedic care, assistive heart monitoring, or respiratory care. Additionally, researchers are investigating new strategies both in clinical trials and in the laboratory. While most research is currently focused on Duchenne Muscular Dystrophy, some of these investigational treatments may also benefit those with Becker Muscular Dystrophy.

Are you affected by a Becker Muscular Dystrophy and want to explore clinical trial options with your physician?

At myTomorrows, we have a team of Patient Navigators who are medically trained, multi-lingual professionals, who help you and your physician explore your treatment options and support you through your journey.

You can book a call with a Patient Navigator to discuss your options and learn more about participating in clinical trials .