Muscular dystrophy refers to a group of genetic diseases that cause progressive muscle weakness and loss. There are more than 30 types of muscular dystrophy, all with different causes and symptoms. Though the most common types appear during childhood, other forms affect adults only.
Muscular dystrophy is generally caused by mutations in the genes that provide instructions for making essential muscle proteins. People typically inherit these mutations from their parents, but some muscular dystrophies can arise from new mutations (not inherited from parents). Muscular dystrophy has no cure, but available treatments can reduce symptoms and slow disease progression.
Common types of muscular dystrophy
Duchenne muscular dystrophy (DMD)
DMD is the most common form of muscular dystrophy, accounting for about a third of all muscular dystrophies. It affects about one in every 3,500 male births. Duchenne patients have a mutation in the DMD gene that causes a lack of dystrophin protein. Dystrophin maintains the structure of muscle fibers, so without dystrophin, a patient’s muscles gradually degrade.
The first signs of DMD usually occur between ages 1 and 3. As they grow, boys start to have difficulty running, jumping, or standing, and most of them need a wheelchair by their teen years. Muscle degradation can be severe enough to shorten life expectancy, though modern treatments can generally slow muscle deterioration, so it is not uncommon for patients to live into their 30s and 40s.
Becker muscular dystrophy (BMD)
Like DMD, BMD also is caused by a mutation in the DMD gene. However, BMD is much milder because the mutation leads to the production of a truncated, but still somewhat functional, protein. Patients typically do not develop symptoms until after age 10, or even into adulthood. Symptoms may include issues with the heart, lungs, joints and skeletal muscles. Most patients are able to maintain an active lifestyle without the need to use a wheelchair.
Emery-Dreifuss muscular dystrophy (EDMD)
EDMD is a slowly progressing form of muscular dystrophy characterized by weakness in the skeletal and heart muscles. This type of muscular dystrophy affects men more often than women.
Facioscapulohumeral muscular dystrophy (FSHD)
FSHD usually emerges in the teen years or early adulthood. Severity differs among patients, but most FSHD patients experience muscle weakness in the face and shoulders. They usually have difficulty raising their arms, whistling, and making certain facial expressions, such as closing their eyes tightly.
Limb-girdle muscular dystrophy (LGMD)
LGMD is associated with a weakening of both the shoulder and upper-arm muscles and the central hip muscles. LGMD can appear as early as childhood and as late as middle age, and usually progresses very slowly. Muscle degradation linked to LGMD can result in a waddle-like gait and difficulty reaching overhead. In advanced stages of LGMD, heart and breathing muscles also may be affected.
Myotonic dystrophy (DM)
Myotonic dystrophy typically does not develop until adulthood. There are two types of myotonic dystrophy, depending on which gene is mutated. Patients with myotonic dystrophy have difficulty contracting and relaxing their muscles at will. Symptoms typically appear first in neck and facial muscles. Myotonic dystrophy also has an early childhood form known as Steinert’s disease.
Oculopharyngeal muscular dystrophy (OPMD)
OPMD is a type of muscular dystrophy characterized by weakening in the muscles that control the eyes and the throat. Symptoms appear later in life, around age 40 to 60. The first symptoms usually are difficulty swallowing and drooping eyelids. As the disease progresses, patients may have weakening in the muscles of the shoulders or pelvis, which may extend to the legs.
Tibial muscular dystrophy (TMD)
TMD is a form of muscular dystrophy characterized by weakness and wasting of the muscles of the ankles, which progresses to the muscles of the shinbone (the tibia) in the front of the lower leg. This type of muscular dystrophy is prevalent in Finland.
Congenital muscular dystrophies (CMDs)
CMDs refer to a group of muscular dystrophies characterized by muscle weakness and wasting (atrophy) from birth or very early on in life. CMDs are caused by genetic mutations, which may be inherited or arise anew.
Bethlem myopathy is a rare and progressive form of CMD. The symptoms of this type of CMD can be apparent in the womb, when the fetus may show decreased movement. Infants usually show hypotonia (low muscle tone) and torticollis (stiff neck). They also may show delayed development — learning to sit and walk later than usual. Some children may develop breathing problems, or a type of muscle wasting called cachexia.
Fukuyama congenital muscular dystrophy (FCMD)
FCMD is a type of CMD found almost exclusively in Japan. Children with FCMD have hypotonia from birth, and also may display weak suckling and crying. FCMD can impair brain development and cause seizures. Children with the disease may have impaired vision, eye abnormalities, and progressive heart conditions.
Muscle-eye-brain diseases (MEBs)
MEBs occur primarily in Finland and affect the skeletal muscles, the eyes, and the brain. Infants born with this disease have hypotonia, as well as cognitive disability, mental retardation, and severe developmental delays. Patients also may develop eye problems, which can lead to blindness.
Rigid spine muscular dystrophy (RSMD)
RSMD is a rare form of CMD characterized by muscle weakness at birth or shortly after. As the disease progresses, the muscles around the spine weaken, and the joints where the vertebrae meet develop abnormalities that cause stiffness in the neck and back. Some patients develop scoliosis (abnormal sideways curvature of the spine). Many children with RSMD have difficulty breathing, especially at night.
Ullrich congenital muscular dystrophy (UCMD)
UCMD has characterized by poor head control and hypotonia at birth. Some children with UCMD may have hypermobility in the finger and wrist joints, which allows too much movement in these joints. Some children also may develop scoliosis.
Walker-Warburg syndrome (WWS)
WWS is a rare form of CMD characterized by hypotonia at birth, which worsens over time. WWS also is associated with brain abnormalities, which can cause delayed development, intellectual disability and seizures. Some infants with WWS also may have eye abnormalities, which can cause impaired vision.
Last updated: Aug. 27, 2019
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