Muscular Dystrophies are genetic disorders of muscle. There are dozens of different muscular dystrophies, many of which are rare in the overall population.
Some of the common types of muscular dystrophies are described below. At Kennedy Krieger, we have expertise in and welcome those with both rare and common disorders of muscle.
Duchenne Muscular Dystrophy:
Duchenne muscular dystrophy is one of the most common inherited disorders worldwide. It is a disorder that affects boys almost exclusively. Parents may first see that their three-to-five year old child frequently falls, runs slowly, walks on his toes or has a waddling gait. The child’s calves are often unusually large. Weakness is initially most pronounced in the hips and upper leg muscles, but will include most voluntary muscles over time, including those responsible for respiration. The heart similarly becomes weak over time. Weakness of the heart and respiratory muscles make this a fatal disorder that requires careful medical management.
Facioscapulohumeral Muscular Dystrophy:
Facioscapulohumeral (FSH) dystrophy is a common muscular dystrophy in which there is progressive weakness of the face, upper arms, and shoulder regions, as well as the legs. The symptoms of FSH dystrophy may appear during childhood with severe facial and limb weakness or develop slowly and gradually in adulthood with progressive difficulty closing the eyes and lifting objects, as well as tripping. The disease is caused by degeneration of muscle due to a specific chromosomal deletion. This deletion is inherited from one generation to the next.
Myotonic Muscular Dystrophy:
Myotonic muscular dystrophy is a common multi-system disorder that affects the skeletal muscles (the muscles that move the limbs and trunk), as well as smooth muscles (the muscles that control the digestive system) and cardiac muscles of the heart. Symptoms of myotonic dystrophy might include difficulty releasing one's grip (myotonia), weakness of muscles in the hands and feet, difficulty swallowing, and abnormal heart rhythms. Non-muscle symptoms may include learning difficulties, daytime sleepiness, infertility, and early cataracts. There are two known forms of this disease (Myotonic Dystrophy Type 1 and Myotonic Dystrophy Type 2). Both are caused by abnormal expansions of repeated areas of genes. In Myotonic Dystrophy Type 1, the repeat expansion enlarges with each generation, frequently leading to earlier onset and increased severity of symptoms with each affected generation. Myotonic Dystrophy Type 1 therefore frequently affects children in families with this disorder.
Limb Girdle Muscular Dystrophy:
The Limb Girdle muscular dystrophies (LGMD) comprise at least a dozen different specific entities. Each of these distinct disorders is in itself rare. Patients with LGMD usually begin to have symptoms in adolescence or early adulthood; however, some forms of LGMD are more severe, with symptoms beginning in childhood. Typically, these symptoms include weakness in the shoulders, hips, upper arms, and legs. For example, patients may have progressive difficulty lifting or climbing stairs. In some forms of LGMD, the heart muscle is also affected. Although LGMD is inherited, there is frequently no family history of this disorder.