Understanding the science of Duchenne

Duchenne is a genetic disease, which means there is a mutation — or error — in one of the body's genes.

In Duchenne, the error occurs in the instructions used to make a protein called dystrophin. Dystrophin is needed by muscles in the body to protect them as they contract and relax. Children with Duchenne are unable to make the dystrophin protein, which causes their muscles to weaken over time.

A closer look at our body's instructions

Amino acids and proteins are the building blocks of life. Our bodies use amino acids to make proteins, which are essential for our bodies to function. Each protein has a specific job, for instance helping you digest food, helping your hair and nails grow, or helping you fight off infection. To make these important proteins, the body needs instructions so it knows which protein to make and how to make it. These instructions are found in our DNA.

protein

amino acid

DNA is short for deoxyribonucleic (dee-oxy-rye-bo-new-clay-ick) acid. It is found in nearly every cell in our body, and carries all of our genetic information.

A length or section of DNA is called a gene. Each gene is made up of smaller parts called introns and exons. When the body needs to make a protein, instructions in the DNA are given to a similar molecule called RNA, or ribonucleic (rye-bo-new-clay-ick) acid. During this process, the introns are removed and all the exons are linked together to make one long chain of instructions, which are then carried to another part of the cell by messenger RNA (mRNA).

Duchenne Muscular Dystrophy Exon Skipping

gene

exon

DNA

Once there, particles in the cells called ribosomes “read” the instructions and make the correct protein using amino acids.

Duchenne Muscular Dystrophy Exon Skipping

gene

exon

DNA

Genetic mutations in Duchenne

The mRNA shown below comes from the dystrophin gene, and contains 79 exons that are linked together to form the instructions for making dystrophin protein. Researchers have discovered that mutations, or errors, in the dystrophin gene alter the instructions for making dystrophin.


produces an
important protein
needed in muscles

dystrophin
protein

Types of mutations include:

  • Large deletions: One or more exons are missing from the dystrophin gene
  • Large duplications: One or more exons have extra copies in the dystrophin gene
  • Other changes: Small changes, such as tiny deletions or changes in a single letter in the instructions
Types of Mutations Found in Duchenne Muscular Dystrophy

72%
large deletions

7%
large duplications

20%
other

The most common mutation in people with Duchenne is a deletion of one or more exons. Much like a puzzle, these missing pieces prevent the remaining exons from fitting together properly.

Exon deletion (missing exon)

What is Exon Deletion in Duchenne Muscular Dystrophy

This causes errors in the instructions for making dystrophin, and the body is not able to produce a working dystrophin protein.


Effect of Exon Skipping in Duchenne Muscular Dystrophy

When exons do not fit together

Dystrophin protein
cannot be created

Why mutations matter

Scientists have recorded more than 1,800 mutations in the DMD gene in people with the Duchenne and Becker forms of muscular dystrophy. Knowing and understanding your child’s mutation is a key step in considering how to manage and treat the disease.

To find out what specific mutation your child has, you will need a genetic test. With this information, you and your child’s doctor can determine how to manage Duchenne, including whether your child is a candidate for clinical trials, and/or whether there are any potential treatment options.

Learn more about genetic testing

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