Limb-girdle muscular dystrophies

Definition

Limb-girdle muscular dystrophies include at least 18 different inherited disorders, which first affect the muscles around the shoulder girdle and hips. These diseases get worse, and may eventually involve other muscles.

Alternative Names

Muscular dystrophy - limb-girdle type (LGMD)

Causes

Limb-girdle muscular dystrophies are a large group of genetic diseases in which there is muscle weakness and wasting (muscular dystrophy).

In most cases, both parents must pass on the non-working (defective) gene for a child to have the disease (autosomal recessive disorder). However, in some rare types only one parent needs to pass on the bad gene to affect the child (autosomal dominant disorder). For some of these conditions, the defective gene has been discovered. For others, the gene is not yet known.

An important risk factor is having a family member with muscular dystrophy.

Symptoms

Typically, the first sign is pelvic muscle weakness (difficulty standing from a sitting position without using the arms, difficulty climbing stairs). The weakness starts in childhood to young adulthood.

Other symptoms include:

• Abnormal, sometimes waddling, walk
• Joints that are fixed in a contracted position (late in the disease)
• Large and muscular-looking calves (pseudohypertrophy), which are not actually strong
• Loss of muscle mass, thinning of certain body parts
• Low back pain
• Palpitations or passing-out spells
• Shoulder weakness
• Weakness of the muscles in the face (later in the disease)
• Weakness in the muscles of the lower legs, feet, lower arms, and hands (later in the disease)

Exams and Tests

• Blood creatine kinase levels
• DNA testing
• Echocardiogram or ECG
• Electromyogram (EMG) testing
• Muscle biopsy

Treatment

There are no known treatments that reverse the muscle weakness. Gene therapy may become available in the future. Supportive treatment can decrease the complications of the disease.

Management is tailored to the patient and his or her symptoms. It includes:

• Heart monitoring
• Mobility aids
• Physical therapy
• Respiratory care
• Weight control

Surgery is sometimes needed for any bone or joint problems.

Support Groups

The Muscular Dystrophy Association is an excellent resource (800-572-1717).

Outlook (Prognosis)

In general, people tend to have weakness that slowly gets worse in affected muscles and spreads.

The disease causes loss of movement or dependence on a wheelchair within 20 - 30 years.

Heart muscle weakness and abnormal electrical activity of the heart can increase the risk of palpitations, fainting, and sudden death. Most patients with this group of diseases live into adulthood, but do not reach their full life expectancy.

Possible Complications

• Abnormal heart rhythms
• Contractures of the joints
• Difficulties with activities of daily living due to shoulder weakness
• Progressive weakness, which may lead to needing a wheelchair

When to Contact a Medical Professional

Call your health care provider if you or your child feel weak while rising from a squatting position. Call a geneticist if you or a family member has been diagnosed with muscular dystrophy and you are planning a pregnancy.

Prevention

Genetic counseling may guide some families about their risks and help with family planning.

Some of the complications can be prevented with appropriate treatment. For example, a cardiac pacemaker or defibrillator can significantly reduce the risk of sudden death due to an abnormal heart rhythm. Physical therapy may be able to prevent or delay contractures and improve quality of life.

Affected people may want to do DNA banking. DNA testing is recommended for those who are affected, in order to identify the family gene mutation. Once the mutation is found, prenatal DNA testing, testing for carriers, and preimplantation genetic diagnosis are possible.

References

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