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The Genetics of DMD

Understanding what drives the disease

How do genes cause DMD?

Damaged genes rob the body of a key protective protein

DMD is caused by changes (mutations) in a certain gene, which in turn change the way the body works, leading to DMD.

Genes are made up of DNA, a code that tells the cells in our body how to make the building blocks of our bodies—called proteins. Proteins are needed to make and replace cells.

In DMD, there is a change (called a mutation) in the gene that tells the body to make dystrophin, a protective protein that’s necessary to keep the muscles working properly. Because of the change, the body stops making dystrophin, and without dystrophin, muscle cells are easily damaged.

DMD can be caused by different types of mutations

Most cases of DMD are caused when large pieces of the dystrophin gene are lost or erased (‘deletions’). Less often, large pieces of the dystrophin gene are copied or duplicated (‘duplications’). DMD can also be caused by other, smaller changes in the DNA code.

The type of mutation can impact which treatments work

Although most therapeutic strategies can be used regardless of the genetic mutation, in some cases treatment specifically for a particular mutation may be available.

How do the genetic mutations that cause DMD happen?

The mutation in the gene that codes for dystrophin can
be either:

  • Passed down through the family (inherited); or
  • Caused by a new genetic change–called “spontaneous mutation”

Spontaneous mutations can occur without any family history of the disease. These new mutations could then be passed onto the next generation. Most DMD cases are from inherited mutations, as shown in the graphic:


Important Terms and Concepts

Basic terms and key definitions

Neuromuscular disorders

Neuromuscular disorders affect the muscles and nerves, and most of the causes are genetic. This means they are either passed down through the family or caused by changes in an individual person’s genes.

Most neuromuscular disorders cause muscle weakness that worsens over time. Signs and symptoms of neuromuscular diseases can vary and may be mild, moderate, or severe.

Most often, when a child has a neuromuscular disease, they don’t grow and develop as fast as other children their age. They are often slow to start lifting their head, sitting, walking, and talking.

Treatment and supportive care may improve the symptoms of a neuromuscular disorder, increasing mobility and even life expectancy.

Muscular dystrophy

Muscular dystrophy is the term for a group of neuromuscular disorders that cause muscle weakness and muscle loss.

Duchenne muscular dystrophy (DMD) is a type of muscular dystrophy that causes muscle weakness that worsens over time. The progression and symptoms can vary from person to person.

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Date of preparation: September 2022