Causes and Risks of Muscular Dystrophy
Muscular dystrophy is a blanket term for genetic-related conditions that cause dysfunction in the body’s muscles. The body replaces the damaged muscle tissue with fat and/or scar tissue, affecting movement and elasticity. While muscular dystrophy is largely considered a childhood disease, the condition can affect people of all ages.
The most common muscular dystrophy types are Duchenne (DMD) and Becker muscular dystrophies (BMD), which occurs in males in early childhood to adolescent years. At the cellular level, muscular dystrophy occurs when a genetic abnormality or mutation causes dystrophin to be absent from muscle cells. Dystrophin is responsible for making healthy muscle cells. The protein strengthens muscle fibers and keeps them from damage when they contract and relax.
To understand how muscular dystrophy is inherited, remember that a male child has two sex chromosomes, X and Y, while a girl has two X chromosomes. A mother contributes to the X chromosome while the father contributes an X or Y chromosome. Muscular dystrophy is a genetic disorder inherited in one of three ways:
Autosomal dominant. Only one parent passes on a faulty gene for muscular dystrophy. If a parent has this type of muscular dystrophy gene, the chances his or her child will have muscular dystrophy is 50 percent if the other parent does not have the muscular dystrophy gene. Myotonic dystrophy and oculopharyngeal muscular dystrophies are examples of autosomal dominant disorders.
Autosomal recessive. Both parents carry a recessive gene. The parents do not typically have muscular dystrophy symptoms, but instead, pass the condition to their children. Examples of autosomal recessive muscular dystrophy are limb-girdle type 2 and distal myopathy.
X-linked recessive. Mothers typically carry the X-linked trait. If they have a boy, the boy will have muscular dystrophy. If they have a girl, she will be a carrier for the disease. X-linked recessive muscular dystrophy types include Duchenne, Becker, and Emery-Dreifuss.
Genetic counseling opportunities
The greatest risk factor for muscular dystrophy is having a family history of the condition. Males are also at increased risk for Duchenne and Becker muscular dystrophy. However, other muscular dystrophy varieties affect males and females equally.
Those with known cases of muscular dystrophy in their families may wish to consider genetic counseling. This includes using a couple’s family medical history to determine the likelihood their child could have muscular dystrophy. While these are only predictions based on genetic possibilities, they can help guide the parent’s decisions regarding options for choosing to conceive.
Sources:
- American Academy of Neurology
- Corticosteroids for Duchenne Muscular Dystrophy.
American Academy of Orthopaedic Surgeons - Muscular Dystrophy.
Centers for Disease Control and Prevention - Facts About Muscular Dystrophy.
Cleveland Clinic - Muscular Dystrophy.
Genetics Home Reference - DMD.
Genetics Home Reference - What Is Duchenne and Becker Muscular Dystrophy?
KidsHealth - Muscular Dystrophy.
MayoClinic.com - Muscular Dystrophy.
Muscular Dystrophy Association - Duchenne Muscular Dystrophy (DMD).
National Institute of Neurological Disorders and Stroke - What Is Muscular Dystrophy?
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