What is muscular dystrophy?

Muscular dystrophy refers to a group of more than 30 inherited (genetic) diseases that cause muscle weakness. These conditions are a type of myopathy, a disease of the skeletal muscles. Over time, muscles shrink and become weaker, affecting your ability to walk and perform daily activities like brushing your teeth. The disease also can affect your heart and lungs.

Some forms of muscular dystrophy are apparent at birth or develop during childhood. Some forms develop later during adulthood. Currently, there isn’t a cure.

How common is muscular dystrophy?

Muscular dystrophy is a rare condition.

Who might get muscular dystrophy?

Muscular dystrophy often runs in families. A child who has a parent with muscular dystrophy may inherit a mutated (changed) gene that causes muscular dystrophy. Some people have the mutated gene but don’t have muscular dystrophy. These healthy adults (carriers) can pass the mutated gene to their child, who may develop the disease.

What are the types of muscular dystrophy?

There are more than 30 different types of muscular dystrophy. Some of the more common forms include:

  • Duchenne muscular dystrophy (DMD): This condition tends to affect boys between the ages of 2 to 5, but girls can get it, too. You may notice that your toddler has a hard time running, walking or jumping. As the disease progresses, it can affect a child’s heart and lungs. DMD is the most common form of muscular dystrophy. It affects approximately six out of 100,000 children in North America and Europe.
  • Becker muscular dystrophy (BMD): BMD is the second most common muscular dystrophy. Symptoms of BMD can appear anytime between age 5 and 60, but typically come on during the teen years. Males are more likely to get BMD. The disease affects the hip, thigh and shoulder muscles, and eventually the heart. Approximately one out of 18,000 to 30,000 U.S. boys develop BMD.
  • Facioscapulohumeral muscular dystrophy (FSHD): FSHD is the third most common muscular dystrophy. The disease affects muscles in the face, shoulder blades and upper arms. Symptoms tend to appear before age 20. About four out of 100,000 people in the U.S. have this form.
  • Congenital muscular dystrophies (CMD): Congenital conditions like CMD are present at birth. An infant may have weak muscles, a curved spine and joints that are too stiff or loose. Children with CMD may have learning disabilities, seizures and vision problems.
  • Emery-Dreiffus muscular dystrophy (EDMD): This condition tends to affect children. Symptoms, such as weak shoulders, upper arms and calf muscles, appear by age 10. EDMD also affects the heart.
  • Limb-girdle muscular dystrophy (LGMD): This disease affects the muscles closest to the body including the shoulders and hips. It affects people of all ages. Approximately two out of 100,000 people in the U.S. have LGMD.
  • Myotonic dystrophy: People with myotonia have trouble relaxing their muscles. For instance, you might find it difficult to let go of a loved one’s hand. The disease also affects the heart and lungs. This condition tends to affect adults of European descent and occurs in approximately 10 out of 100,000 people.
  • Oculopharyngeal muscular dystrophy (OPMD): This rare form of muscular dystrophy weakens muscles in the eyelids and throat. Symptoms, such as droopy eyelids (ptosis) and difficulty swallowing (dysphagia), often appear between the 40s and 60s. About one in 100,000 people have OPMD.

What causes muscular dystrophy?

Genetic mutations, or changes, cause most forms of muscular dystrophy. One or both parents may pass a faulty gene to their child even if the parent doesn’t have the condition. Rarely, a person develops muscular dystrophy spontaneously, meaning there’s no known cause.

What are the symptoms of muscular dystrophy?

Muscle weakness is the primary symptom of muscular dystrophy. Depending on the type, the disease affects different muscles and parts of the body. Other signs of muscular dystrophy include:

  • Enlarged calf muscles.
  • Difficulty walking or running.
  • Unusual walking gait (like waddling).
  • Trouble swallowing.
  • Heart problems, such as arrhythmia and heart failure (cardiomyopathy).
  • Learning disabilities.
  • Stiff or loose joints.
  • Muscle pain.
  • Curved spine (scoliosis).
  • Breathing problems.

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