Muscular Dystrophy

Muscular dystrophy refers to a group of more than 30 genetic (inherited) conditions that affect the functioning of your muscles. In general, the symptoms of muscular dystrophy worsen over time. These conditions are a type of myopathy, a disorder of your skeletal muscles.

Depending on the type, muscular dystrophy can affect your ability to move, walk and perform daily activities. It can also affect muscles that help your heart and lungs function.

Some forms of muscular dystrophy are present at birth or develop during childhood. Other forms develop during adulthood.

Types of muscular dystrophy

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

• Duchenne muscular dystrophy (DMD): This is the most common form of muscular dystrophy. It mainly affects children assigned male at birth (AMAB), but children assigned female at birth (AFAB) can also have a milder version of it. As DMD progresses, it affects your heart and lungs.
• Becker muscular dystrophy (BMD): BMD is the second most common type of muscular dystrophy. It mainly affects people AMAB, but people AFAB can have milder symptoms of the condition. Symptoms of BMD can appear any time between the ages of 5 and 60, but they typically begin by your teenage years. The severity of BMD varies from person to person.
• Myotonic dystrophy: This is the most common type of muscular dystrophy that’s diagnosed in adulthood. It affects adults AFAB and adults AMAB equally. People with myotonic dystrophy have difficulty relaxing their muscles after using them. The condition can also affect your heart and lungs and cause endocrine issues such as thyroid disease and diabetes.
• Congenital muscular dystrophies (CMD): CMD refers to a group of muscular dystrophies that become apparent at or near birth (“congenital” means “present from birth”). CMD causes overall muscle weakness with possible joint stiffness or looseness. Depending on the type, CMD may also involve spinal curvature (scoliosis), breathing issues, intellectual disabilities, learning disabilities, eye issues or seizures.
• Distal muscular dystrophy: This type affects the muscles of your hands, feet, lower arms and lower legs. It tends to affect people in their 40s and 60s.
• Emery-Dreifuss muscular dystrophy (EDMD): EDMD mainly affects children and young adults AMAB. It tends to cause muscle weakness in your shoulders, upper arms and shins. EDMD also affects your heart. The condition usually progresses slowly.
• Facioscapulohumeral muscular dystrophy (FSHD): FSHD most commonly affects muscles in your face, shoulders and upper arms. Symptoms tend to appear before age 20. About 4 out of 100,000 people in the U.S. have this form.
• Limb-girdle muscular dystrophy (LGMD): LGMD affects the muscles in your upper arms, upper legs, shoulders and hips. It affects people of all ages. Approximately 2 out of 100,000 people in the U.S. have LGMD.
• Oculopharyngeal muscular dystrophy (OPMD): OPMD weakens muscles in your eyelids and throat. Symptoms, such as droopy eyelids (ptosis) and difficulty swallowing (dysphagia), often appear in your 40s or 50s. About 1 in 100,000 people have OPMD.

How common is muscular dystrophy?

Muscular dystrophy is relatively rare. All of the different types combined affect about 16 to 25 per 100,000 people in the U.S.

The most common childhood form is Duchenne muscular dystrophy. The most common adulthood form is myotonic dystrophy.