Muscular dystrophy types
Muscular dystrophy (MD) is a genetic disorder that weakens the muscles that help the body move. People with MD have incorrect or missing information in their genes, which prevents them from making the proteins they need for healthy muscles. Because MD is genetic, people are born with the problem — it's not contagious and you can't catch it from someone who has it.
MD weakens muscles over time, so children, teens, and adults who have the disease can gradually lose the ability to do the things most people take for granted, like walking or sitting up. Someone with MD might start having muscle problems as a baby or their symptoms might start later. Some people even develop MD as adults.
Several major forms of muscular dystrophy can affect people, each of which weakens different muscle groups in various ways:
- Duchenne muscular dystrophy (DMD), the most common type of the disease, is caused by a problem with the gene that makes a protein called dystrophin. This protein helps muscle cells keep their shape and strength. Without it, muscles break down and a person gradually becomes weaker. DMD affects boys. Symptoms usually start between ages 2 and 6. By age 10 or 12, kids with DMD often need to use a wheelchair. The heart may also be affected, and people with DMD need to be followed closely by a lung and heart specialist. They can also develop scoliosis (curvature of the spine) and tightness in their joints. Over time, even the muscles that control breathing get weaker, and a person might need a ventilator to breathe.
- Becker muscular dystrophy (BMD), like DMD, affects boys. The disease is very similar to DMD, but its symptoms may start later and can be less severe. With BMD, symptoms like muscle breakdown and weakness sometimes don't begin until age 10 or even in adulthood. People with BMD can also have breathing, heart, bone, muscle, and joint problems. Many people with BMD can live long, active lives without using a wheelchair.
- Emery-Dreifuss muscular dystrophy (EDMD) typically starts causing symptoms in late childhood to early teens and sometimes as late as age 25. EDMD is another form of muscular dystrophy that affects mostly boys. It involves muscles in the shoulders, upper arms, and shins, and it often causes joint problems (joints can become tighter in people with EDMD). The heart muscle may also be affected.
- Limb-girdle muscular dystrophy (LGMD) affects boys and girls equally, weakening muscles in the shoulders and upper arms and around the hips and thighs. LGMD can begin as early as childhood or as late as mid-adulthood, and it often progresses slowly. Over time, a wheelchair might be necessary to get around. There are many different types of LGMD, each with its own specific features.
- Facioscapulohumeral muscular dystrophy (FSHD) can affect both guys and girls, and it usually begins during the teens or early adulthood. FSHD affects muscles in the face and shoulders and sometimes causes weakness in the lower legs. People with this type of MD might have trouble raising their arms, whistling, or tightly closing their eyes. How much a person with this form of muscular dystrophy is affected by the condition varies from person to person. It can be quite mild in some people.
- Myotonic dystrophy (MMD) is a form of muscular dystrophy in which the muscles have difficulty relaxing. In teens, it can cause a number of problems, including muscle weakness and wasting (where the muscles shrink over time), cataracts, and heart problems.
- Congenital muscular dystrophy (CMD) is the term for all types of MD that show signs in babies and young children, although the MD isn't always diagnosed right away. Like other forms of MD, CMD involves muscle weakness and poor muscle tone. Occurring in both girls and boys, it can have different symptoms. It varies in how severely it affects people and how quickly or slowly it worsens. In rare cases, CMD can cause learning or intellectual disabilities.
The life expectancy for many of these forms of muscular dystrophy depends on the degree to which a person's muscles are weakened as well as how much the heart and lungs are affected.