OAPD Organization for the Aid of People with Dystrophies
About us Muscular dystrophies How to help Contacts Versão em Português

What are Progressive Muscular Dystrophies

Quick access
The muscular dystrophies (MD) are genetic diseases that cause progressive weakness in muscles. There are over 30 different forms of dystrophy, and the most common is Duchenne, which also is one of the most severe.

MAIN TYPES OF PROGRESSIVE MUSCULAR DYSTROPHY

Duchenne Muscular Dystrophy (DMD)

Also known as Pseudohypertrophic.

Cause

An absence of dystrophin, a protein that helps keep muscle cells intact.

Onset

Early childhood - about 2 to 6 years.

Symptoms

Generalized weakness and muscle wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are often enlarged.

Progression

DMD eventually affects all voluntary muscles, and the heart and breathing muscles. Survival is rare beyond the early 30s.

Inheritance

X-linked recessive. DMD primarily affects boys, who inherit the disease through their mothers. Women can be carriers of DMD but usually exhibit no symptoms.

About

The most common childhood form of muscular dystrophy. Early signs of Duchenne are frequent falling, difficulty getting up from a sitting or lying position, and a waddling gait. Another hallmark is the apparent enlargement of the calf, which is due to an accumulation of fat and connective tissue in the muscle. A blood sample shows a very high level of creatine kinase (CK), an enzyme that leaks out of damaged muscle.

The use of orthopedic devices and physical therapy can prolong the ability to walk. However, a wheelchair will be needed by the age of 12.

Breathing becomes affected during the later stages of Duchenne, leading to respiratory infections. These are often successfully treated with antibiotics and respiratory therapy. Severe respiratory and heart problems mark the boy's early 20s.

Source: MDA

<< Back

Myotonic Muscular Dystrophy (MMD)

Also known as Steinert Disease, dystrophia myotonica (DM).

Cause

A repeated section of DNA on either chromosome 19 or chromosome 3.

Onset

Congenital form appears at birth. More common form may begin in teen or adult years.

Symptoms

Generalized weakness and muscle wasting first affecting the face, lower legs, forearms, hands and neck, with delayed relaxation of muscles after contraction common. Other symptoms involve the gastrointestinal system, vision, heart or respiration. Learning disabilities occur in some cases. Congenital myotonic dystrophy is the more severe form.

Progression

Progression is slow, sometimes spanning 50 to 60 years.

Inheritance

Autosomal dominant; the disease may be inherited through either the father or the mother.

About

The most common adult form of muscular dystrophy. Its name underscores an unusual symptom found only in this form of dystrophy - myotonia - which is similar to a spasm or stiffening of muscles after use.

The disease causes muscle weakness and affects the central nervous system, heart, gastrointestinal tract, eyes (cataracts) and endocrine glands. Although muscle weakness progresses slowly, this symptom can vary greatly, even among members of a single family. Most often muscle weakness doesn't hamper daily living for many years after symptoms first occur.

Congenital myotonic dystrophy is a rare form of the disorder occurring almost exclusively in infants of mothers with the adult form of the disease. At birth, infants can show symptoms of the disease, including severe weakness, difficulty in sucking and swallowing, and impaired breathing. Delayed motor development and mental retardation are common.

The cardiac problems can be serious and should be followed carefully by a physician. Drug therapy or a cardiac pacemaker may be necessary.

Source: MDA

<< Back

Limb-Girdle Muscular Dystrophy (LGMD)

Cause

A mutation in any of at least 15 different genes that affect proteins necessary for muscle function.

Onset

Childhood to adulthood.

Symptoms

Weakness and wasting first affecting the muscles around the shoulders and hips (limb girdles).

Progression

Usually progresses slowly, with cardiopulmonary complications sometimes occurring in later stages of the disease.

Inheritance

Some types are autosomal dominant, meaning LGMD is inherited from one parent. Other types are autosomal recessive and occur when a faulty gene is inherited from each parent.

About

In the most common forms, the disease causes progressive weakness that starts in the hips and moves to the shoulders. The weakness progresses to include the arms and legs. Within 20 years of onset, walking is difficult or impossible.

Source: MDA

<< Back

Facioscapulohumeral Muscular Dystrophy (FSH or FSHD)

Also known as Landouzy-Dejerine.

Cause

A missing piece of DNA on chromosome 4.

Onset

Usually by age 20.

Symptoms

Weakness and wasting of the muscles around the eyes and mouth and of the shoulders, upper arms and lower legs initially, with later weakness of abdominal muscles and sometimes hip muscles.

Progression

Progresses slowly with some periods of rapid deterioration. Disease may span many decades.

Inheritance

Autosomal dominant; the disease may be inherited through either the father or the mother, or it may occur without a family history.

About

Common early signs are a forward sloping of the shoulders as well as difficulty raising the arms over the head and closing the eyes. Progression is slow, with long periods of stability interspersed with shorter periods of rapid muscle deterioration and increased weakness. The muscles of the face and shoulder area (shoulder "girdle") are the first affected. The weakness spreads to the muscles of the abdomen, feet, upper arms, pelvic area and lower arms, usually in that order. The disease ranges in severity from very mild to considerably disabling, with impairment of walking, chewing, swallowing and speaking. About half of those with the disorder retain the ability to walk throughout their lives.

Source: MDA

<< Back

Becker Muscular Dystrophy (BMD)

Cause

Insufficient production of dystrophin, a protein that helps keep muscle cells intact.

Onset

Adolescence or adulthood.

Symptoms

Generalized weakness and wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are often enlarged. BMD is similar to Duchenne muscular dystrophy but often much less severe. There can be significant heart involvement.

Progression

Disease progresses slowly and with variability but can affect all voluntary muscles. Most with BMD survive well into mid to late adulthood.

Inheritance

X-linked recessive. BMD primarily affects boys and men, who inherit the disease through their mothers. Women can be carriers but usually exhibit no symptoms.

About

The signs, symptoms and course are very similar to those of Duchenne but generally appear later and progress more slowly.

Becker dystrophy can first appear much later than Duchenne, even as late as age 25. The ability to walk is usually preserved into the 30s.

The severity of the disease varies, and boys and men with Becker dystrophy have a longer life expectancy than those with Duchenne. The severity and rate of progression of Becker dystrophy depends on how much dystrophin is made and how well it functions in the muscles.

The cardiac problems are similar to those in Duchenne and should be followed by a physician. 

Source: MDA

<< Back

Congenital Muscular Dystrophy (CMD)

Cause

Genetic mutations affecting some of the proteins necessary for muscles and sometimes for the eyes and or brain.

Onset

At or near birth.

Symptoms

Generalized muscle weakness with possible joint stiffness or looseness. Depending on the type, CMD may involve spinal curvature, respiratory insufficiency, mental retardation or learning disabilities, eye defects or seizures.

Progression

Varies with type; many are slowly progressive; some shorten life span.

Inheritance

Autosomal recessive or autosomal dominant; these diseases are sometimes inherited through both parents and sometimes inherited from one parent. They can also occur spontaneously because of a newly developed genetic flaw (mutation).

About

Is a group of diseases, not a single disease. These diseases are called "congenital" because symptoms can be noted from birth. One form that has been clearly described is Fukuyama congenital muscular dystrophy. This disorder involves severe weakness of the facial and limb muscles and a generalized lack of muscle tone, usually appearing before 9 months. Joint contractures are common. Brain abnormalities are also present, and most children have severe mental and speech problems. Seizures are often part of the disease. Physical therapy is needed to minimize the contractures.

Another form of congenital dystrophy seems to be related to a deficiency or malfunction of the protein merosin, which normally lies outside muscle cells and links them to the surrounding tissue. The disorder is similar to Fukuyama dystrophy, with muscle weakness evident at birth or in the first few months of life, severe and early contractures and often joint deformities. This disorder has been tentatively named congenital muscular dystrophy with merosin deficiency and appears to be due to an as-yet-unidentified defect on chromosome 6. 

Source: MDA

<< Back

DIAGNOSIS

How is muscular dystrophy diagnosed?

A doctor makes a diagnosis by evaluating the patient's medical history and by performing a thorough physical examination. Essential to diagnosis are details about when weakness first appeared, its severity, and which muscles are affected. Diagnostic tests may also be used to help the doctor distinguish between different forms of muscular dystrophy, or between muscular dystrophy and other disorders of muscle or nerve.

What are some common diagnostic tests?

Studying a small piece of muscle tissue taken from an individual during a muscle biopsy can sometimes tell a physician whether a disorder is muscular dystrophy and which form of the disease it is.

In Duchenne and Becker muscular dystrophy, a muscle protein called dystrophin is either missing, deficient or abnormally formed. This protein can be examined in the muscle sample.

The reason for the flawed or deficient muscle protein is a flawed gene for dystrophin. A test that involves looking at this gene - DNA testing - can be done to diagnose or rule out Duchenne or Becker muscular dystrophies.

Another diagnostic test is the electromyogram (EMG). To do this test, small electrodes are put into the muscle, which allows the doctor to measure the electrical impulses coming from the muscle. The test is uncomfortable.

Another test often performed measures nerve conduction velocity (NCV). During this test, electrical impulses are sent down the nerves of the arms and legs. By measuring the speed of these impulses with electrodes placed on the skin, the doctor can determine whether the nerves are functioning normally. This test is also uncomfortable.

Blood enzyme tests are helpful because degenerating muscles become "leaky." They leak enzymes (proteins that speed chemical reactions), which can then be detected in the blood. The presence of these enzymes in the blood at higher than normal levels may be a sign of muscular dystrophy. One such enzyme is creatine kinase, or CK. The CK level is elevated in many forms of muscular dystrophy, some forms resulting in a higher level than others.


Source: MDA

<< Back