Muscular Dystrophy Health Article

Experimental treatments

Two experimental procedures aiming to cure DMD have attracted a great deal of attention in the past decade. In myoblast transfer, millions of immature muscle cells are injected into an affected muscle. The goal of the treatment is to promote the growth of the injected cells, replacing the defective host cells with healthy new ones. Myoblast transfer is under investigation but remains experimental.

Gene therapy introduces good copies of the altered gene into muscle cells. The goal is to allow the existing muscle cells to use the new gene to produce the protein it cannot make with its abnormal gene. Problems with gene therapy research have included immune rejection of the virus used to introduce the gene, loss of gene function after several weeks, and an inability to get the gene to enough cells to make a functional difference in an affected muscle. Researchers are preparing for the first gene therapy trial for LGMD in the United States. The goal will be to replace the missing sarcoglycan gene(s).

Genetic counseling

Individuals with muscular dystrophy and their families may benefit from genetic counseling for information on the condition and recurrence risks for future pregnancies.

Prognosis

The expected lifespan for a male with DMD has increased significantly in the past two decades. Most young men will live into their early or mid-twenties. Respiratory infections become an increasing problem as their breathing becomes weaker, and these infections are usually the cause of death.

The course of the other muscular dystrophies is more variable; expected life spans and degrees of disability are hard to predict, but may be related to age of onset and initial symptoms. Prediction is made more difficult because, as new genes are discovered, it is becoming clear that several of the dystrophies are not uniform disorders, but rather symptom groups caused by different genes.

People with dystrophies having significant heart involvement (BMD, EDMD, myotonic dystrophy) may nonetheless have almost normal life spans, provided that cardiac complications are monitored and aggressively treated. The respiratory involvement of BMD and LGMD similarly requires careful and prompt treatment.

Health care team roles

A pediatrician or family physician often make an initial diagnosis of muscular dystrophy. Pathologists and geneticists evaluate materials collected for testing. Physical therapists may provide supportive services. Braces and other assistive devices may be manufactured by orthotists and others with specialty training. Computer engineers have devised equipment for improving communications. Counselors and nurses provide support to people with muscular dystrophy and their families.

Prevention

There is no way to prevent any of the muscular dystrophies in a person who has the genes responsible for these disorders. Accurate genetic tests, including prenatal tests, are available for some of the muscular dystrophies. Results of these tests may be useful for purposes of family planning.

KEY TERMS

Amniocentesis—A procedure in which a needle is inserted through a pregnant woman's abdomen and into her uterus to withdraw a small sample of the fluid that surrounds the fetus (amniotic fluid) for the purposes of analysis.

Autosomal dominant—Conditions that occur when a person inherits only one abnormal copy of a gene.

Autosomal recessive—Conditions that occur when a person inherits two abnormal copies of a gene, one from each parent.

Becker muscular dystrophy (BMD)—A type of muscular dystrophy that affects older boys and men, and usually follows a milder course than DMD.

Chorionic villus sampling—A medical procedure done during weeks 10-12 of a pregnancy. A needle is inserted into the placenta and a small amount of fetal tissue is withdrawn for analysis.

Contractures—A permanent shortening (as of muscle, tendon, or scar tissue) producing deformity or distortion.

Distal muscular dystrophy (DD)—A form of muscular dystrophy that usually begins in middle age or later, causing weakness in the muscles of the feet and hands.

Duchenne muscular dystrophy (DMD)—The most severe form of muscular dystrophy, DMD usually affects young boys and causes progressive muscle weakness, usually beginning in the legs.

Dystrophin—A protein that helps muscle tissue repair itself. Both DMD and BMD are caused by abnormalities in the gene that instructs the body how to make this protein.

Facioscapulohumeral muscular dystrophy (FSH)—This form of muscular dystrophy, also known as Landouzy-Dejerine condition, begins in late childhood to early adulthood and affects both men and women, causing weakness in the muscles of the face, shoulders, and upper arms.

Limb-girdle muscular dystrophy (LGMD)—This form of muscular dystrophy begins in late childhood to early adulthood and affects both men and women, causing weakness in the muscles around the hips and shoulders.

Myotonic dystrophy—This type of muscular dystrophy, also known as Steinert's disease, affects both men and women, causing generalized weakness first seen in the face, feet, and hands. It is accompanied by the inability to relax the affected muscles (myotonia).

Oculopharyngeal muscular dystrophy (OPMD)—This type of muscular dystrophy affects adults of both sexes, causing weakness in the eye muscles and throat.