What is muscular dystrophy?
Muscular dystrophy (MD) is a broad term that describes a genetic (inherited) disorder of the muscles. Muscular dystrophy causes the muscles in the body to become very weak. The muscles break down and are replaced with fatty deposits over time. Defective genes are the cause of muscular dystrophy. The specific gene disorder is known for most of the common
muscular dystrophies, but there are many less common conditions for which the specific defects need to be discovered. A family history of the condition is often but not always present.
Muscular dystrophy is a genetic disorder that is characterized by muscle wasting and weakening. There are over twenty types of muscular dystrophy, each categorized according to which muscles in the body are affected. The most common type of muscular dystrophy is called Duchenne muscular dystrophy (DMD). Another common, though milder form of dystrophy is known as Becker muscular dystrophy (BMD).
Duchenne's muscular dystrophy is an inherited disease of skeletal (voluntary) muscles and the most common form of childhood muscular dystrophy. It generally appears from age three to six years and worsens rapidly. At first, muscle weakness and wasting (atrophy) within the pelvic (hipbone) area occurs followed by similar problems in the shoulder muscles. Eventually, muscle weakness and atrophy affect the trunk and forearms and gradually spread to the major muscles of the body. From 20 to 30 boys of every 100,000 born are affected by Duchenne's muscular dystrophy. Some common problems associated with MD include heart problems, scoliosis, and obesity. Another, less common form of muscular dystrophy is facioscapulohumeral muscular dystophy (FSHD or Landouzy-Dejerine syndrome), affecting mainly facial, shoulder and arm muscles. The heart and diaphragm muscles are also weakened as a result of muscle degeneration. Some people with DMD or BMD often develop cardiomyopathy, a weakened heart condition due to deficiency of the protein dystrophin.
Symptoms vary with the different types of muscular dystrophy. Depending on the type of disease present, symptoms of muscular dystrophy may include a waddling way of walking, difficulty climbing stairs or rising from sitting and repeated falling. As the disease worsens, other abnormalities may develop, such as curvature of the spine, wasting of thigh muscles, abnormal enlargement of the calves and enlargement of the heart. Some forms of MD first appear in infancy or childhood, but others may not appear until middle age or later. As the muscles break down, they are replaced by fat cells. For both Duchenne and Becker muscular dystrophy, the skeletal or voluntary muscles, those that are in the arms, legs, and trunk, are weakened. As these muscles degenerate and get weaker, it becomes increasingly more difficult to get up from either a sitting or lying position, to climb stairs, and to maintain balance.
There is currently no known cure for any of the muscular dystrophies. However, physical therapy and exercise help prevent muscles from contracting permanently around joints. Sometimes surgery is needed to release tight, painful muscles. Physical therapy to prevent contractures (a condition in which shortened muscles around joints cause abnormal and sometimes painful positioning of the joints), orthoses (orthopedic appliances used for support) and corrective orthopedic surgery may be needed to improve the quality of life in some cases. The cardiac problems that occur with Emery-Dreifuss muscular dystrophy and myotonic muscular dystrophy may require a pacemaker. The myotonia (delayed relaxation of a muscle after a strong contraction) occurring in myotonic muscular dystrophy may be treated with medications such as phenytoin or quinine.
More information on muscular dystrophy
What is muscular dystrophy? - Muscular dystrophy is a group of inherited diseases that are characterized by weakness and wasting away of muscle tissue.
What types of muscular dystrophy are there? - There are nine types of muscular dystrophy including Duchenne muscular dystrophy, Becker muscular dystrophy, facioscapulohumeral muscular dystrophy.
What causes Duchenne muscular dystrophy (DMD)? - Duchenne muscular dystrophy is a rapidly progressive form of muscular dystrophy. It is caused by a defective gene.
What're the symptoms of Duchenne muscular dystrophy? - Symptoms of Duchenne muscular dystrophy include progressive muscle weakness of the legs and pelvis, mental impairment or heart problems.
What causes Becker's muscular dystrophy? - Becker muscular dystrophy is a type of dystrophinopathy which include a spectrum of muscle disease caused by mutations in the DMD gene.
What're the symptoms of Becker's muscular dystrophy? - Symptoms of Becker-type muscular dystrophy are similar to those of Duchenne dystrophy, but they are milder and begin later.
What causes limb-girdle muscular dystrophy? - Limb-girdle muscular dystrophy is an inherited disorder, it may be inherited as a dominant, recessive, or X-linked genetic defect.
What're the symptoms of limb-girdle muscular dystrophy? - Symptoms of limb-girdle muscular dystrophy include progressive muscle weakness in the shoulders and hips, together with breathing problems.
What causes facioscapulohumeral muscular dystrophy? - Facioscapulohumeral muscular dystrophy involves progressive muscle weakness and loss of muscle tissue.
What're the symptoms of facioscapulohumeral muscular dystrophy? - Symptoms of facioscapulohumeral muscular dystrophy may begin during infancy, late childhood, or early adulthood.
What causes myotonic dystrophy? - Myotonic dystrophy is caused by an inherited gene defect. Myotonic dystrophy is the most common form of adult muscular dystrophy.
What're the symptoms of myotonic dystrophy? - Symptoms of myotonic dystrophy include muscle weakness and wasting, cataracts, heart problems, constipation and other digestive problems.
How is muscular dystrophy diagnosed? - Diagnosis of muscular dystrophy involves a medical history and physical exam to determine the distribution of symptoms and to rule out other causes.
What's the treatment for muscular dystrophy? - Treatments for muscular include decreased mobility and dexterity, contractures, scoliosis, heart defects, and respiratory weaknesses.