What is muscular dystrophy? Muscular dystrophy is a group of genetic disorders that affect the muscles. These rare diseases cause muscular weakness and degeneration. They mainly affect voluntary skeletal muscles that control movement. Some of them also involve involuntary muscles, such as the heart and muscles in the respiratory and digestive tracts. Abnormal genes cause muscular dystrophy. The genes involved make proteins necessary for normal, healthy muscles. A different gene is responsible for each of the muscular dystrophy types. These genes can be passed from parents to children. The genetic abnormality may also develop spontaneously during development in the womb. Muscle weakness is the main symptom of these disorders. The specific muscular dystrophy symptoms vary with the forms of the disorder and the muscles they affect. All of them are progressive, meaning they get worse with time. The muscular dystrophy types differ in the age of onset (when symptoms begin), affected muscles, severity, and rate of progression. Some develop in childhood, while others do not begin until adulthood. They also differ in the pattern of inheritance—or how people inherit the genes. The pattern of inheritance determines who the disease affects and who is just a genetic carrier. There are more than 30 muscular dystrophy types. The most common forms of muscular dystrophy include: Duchenne muscular dystrophy is the most common type. It mainly affects boys between the ages of 3 and 5 years. In affected families, there is a 50% chance that girls will carry the gene and pass it on to their sons. Girls rarely have symptoms of the disorder. Becker muscular dystrophy is similar to Duchenne. However, it is milder, progresses slower, and tends to develop in males during teenage years. Facioscapulohumeral muscular dystrophy (FSHD) affects boys and girls equally. It typically develops during the teenage years or early 20s. Myotonic muscular dystrophy also affects males and females equally. It most commonly strikes people between the ages of 10 and 30. However, it can begin during infancy or old age. There is no cure for muscular dystrophy. Medications can help ease symptoms and may slow progression. Various forms of therapy can also be useful for managing symptoms. See your doctor if you notice any problems with muscle weakness, mobility, or difficulty with everyday tasks. Doctors routinely check developmental progress in children during well-child visits. This routine medical care can identify potential problems. However, you should contact your child’s doctor for concerns between visits.