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Role of Genetics

The genetic mutation behind Duchenne.

Understanding the cause of Duchenne begins with understanding the role of proteins and genes in how our bodies function.


Proteins are necessary for many important functions in the body, such as digesting our food, growing our bones, or—in the case of the protein called dystrophin—helping our muscles work properly.

Genes are made up of segments, called “exons,” that tell our cells which proteins to make. The dystrophin gene is made up of 79 exons that, when linked together, form the instructions for making dystrophin.

EXONDYS 51 illustration depicting dystrophin gene and exons as part of understanding exon skipping technology

What is a genetic mutation?

A mutation is a change in a person's DNA. Mutations range in size from a small (a single rung on a ladder) to a large segment of DNA. Every mutation causes a different effect on our bodies. A mutation on the dystrophin gene means dystrophin is not produced—resulting in Duchenne.

EXONDYS 51 illustration depicting dystrophin gene and exons as part of understanding exon skipping technology

3 common types of mutations.

Large deletions: one or more exons are missing 72% of people with Duchenne

 

Large duplications: one or more exonds are duplicated 7% of people with Duchenne (Not treatable with EXONDYS 51)

 

Other changes: small deletions or interruptions in the instructions 20% of people with Duchenne (Not treatable with EXONDYS 51)

 

Large deletions: one or more exons are missing 72% of people with Duchenne
13%

 

About 13% of people diagnosed with Duchenne have the genetic mutation that is amenable to EXONDYS 51. Learn what this means.

Large duplications: one or more exonds are duplicated 7% of people with Duchenne (Not treatable with EXONDYS 51)
Other changes: small deletions or interruptions in the instructions 20% of people with Duchenne (Not treatable with EXONDYS 51)

EXONDYS 51 is used to treat Duchenne in patients who have a confirmed mutation in the dystrophin gene that can be treated by skipping exon 51. EXONDYS 51 was approved under accelerated approval. Accelerated approval allows for drugs to be approved based on a marker that is considered reasonably likely to predict a clinical benefit that has not been proven. EXONDYS 51 treatment increased the marker, dystrophin, in skeletal muscle in some patients. Verification of a clinical benefit may be needed for EXONDYS 51 to continue to be approved.

The importance of genetic testing.

While there is presently no cure for Duchenne, advances in research offer hope. Genetic testing can now pinpoint the specific exons that are missing from the dystrophin gene. That’s why it’s so important for every child living with Duchenne to have a current genetic test—and for parents to understand the results.

Your child has a confirmed diagnosis of Duchenne. Have they had a genetic test?

No.

No.

No

Now is the time to talk to your child's doctor about testing.
Learn about genetic testing.

Yes,

a recent test, but I‘m not sure about the results.

Yes,

a recent test, but I‘m not sure about the results.

Yes

Ask your child’s doctor to review the test to see if the genetic mutation is identified. Learn how to read the test results yourself.

Yes,

but it was several years ago.

Yes,

but it was several years ago.

Yes

Test methods have improved in recent years. Talk to your doctor about a retest to identify the mutation.

4 reasons to get a genetic test.
4 reasons to get a genetic test.

How is a genetic test performed? Getting a genetic test is usually as simple as providing a blood or saliva sample.

1.

To confirm a Duchenne diagnosis

2.

To identify the genetic mutation and explore possible therapy options

3.

To facilitate potential clinical trial participation

4.

To assist with family planning

Wondering what to expect?

Get insights into the Duchenne diagnostic process.

3 hexagons in a line denoting steps in the Duchenne diagnostic process: noticing symptoms, initial diagnosis and confirmed diagnosis
See the Steps

Ready to talk to your child’s doctor?

Create a personalized Doctor Discussion Guide.

Doctor discussion guide
Create Your Guide

Related FAQs

How will I know if my child can be treated with EXONDYS 51?

A doctor will need to interpret the test results to consider appropriate treatment options. Learn more about deletions.

Is the treatment effective?

Weekly infusions of EXONDYS 51 helped the body make a shorter form of the dystrophin protein in some boys. View the results from clinical studies.

 

EXONDYS 51 is used to treat Duchenne in patients who have a confirmed mutation in the dystrophin gene that can be treated by skipping exon 51. EXONDYS 51 was approved under accelerated approval. Accelerated approval allows for drugs to be approved based on a marker that is considered reasonably likely to predict a clinical benefit that has not been proven. EXONDYS 51 treatment increased the marker, dystrophin, in skeletal muscle in some patients. Verification of a clinical benefit may be needed for EXONDYS 51 to continue to be approved.

See All FAQs

WHAT IS EXONDYS 51® (eteplirsen)?

EXONDYS 51 is used to treat Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation in the dystrophin gene that can be treated by skipping exon 51.

EXONDYS 51 was approved under accelerated approval. Accelerated approval allows for drugs to be approved based on a marker that is considered reasonably likely to predict a clinical benefit that has not been proven. EXONDYS 51 treatment increased the marker, dystrophin, in skeletal muscle in some patients. Verification of a clinical benefit may be needed for EXONDYS 51 to continue to be approved.

IMPORTANT RISK INFORMATION

Allergic reactions, including rash, hives, fever, flushing, cough, difficulty breathing, wheezing, and low blood pressure have occurred in patients who were treated with EXONDYS 51. Seek immediate medical care if signs and symptoms of allergic reactions occur.

Side effects that happened at least 25% more often in 8 patients treated with EXONDYS 51 by intravenous infusion than in 4 patients treated with an inactive intravenous infusion were problems with balance (38%, 0%), vomiting (38%, 0%), and skin irritation (25%, 0%). The most common side effects were problems with balance and vomiting.

In patients who received EXONDYS 51 for up to 4 years in clinical studies, the following side effects were reported in at least 10% of patients and occurred more often than at the same dose of EXONDYS 51: vomiting, bruising, scratches, joint pain, rash, IV site pain, and infections of the upper airways.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088. You may also report side effects to Sarepta Therapeutics at 1-888-SAREPTA (1-888-727-3782).

READ MORE

WHAT IS EXONDYS 51® (eteplirsen)?

EXONDYS 51 is used to treat Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation in the dystrophin gene that can be treated by skipping exon 51.

EXONDYS 51 was approved under accelerated approval. Accelerated approval allows for drugs to be approved based on a marker that is considered reasonably likely to predict a clinical benefit that has not been proven. EXONDYS 51 treatment increased the marker, dystrophin, in skeletal muscle in some patients. Verification of a clinical benefit may be needed for EXONDYS 51 to continue to be approved.

IMPORTANT RISK INFORMATION

Allergic reactions, including rash, hives, fever, flushing, cough, difficulty breathing, wheezing, and low blood pressure have occurred in patients who were treated with EXONDYS 51. Seek immediate medical care if signs and symptoms of allergic reactions occur.

Side effects that happened at least 25% more often in 8 patients treated with EXONDYS 51 by intravenous infusion than in 4 patients treated with an inactive intravenous infusion were problems with balance (38%, 0%), vomiting (38%, 0%), and skin irritation (25%, 0%). The most common side effects were problems with balance and vomiting.

In patients who received EXONDYS 51 for up to 4 years in clinical studies, the following side effects were reported in at least 10% of patients and occurred more often than at the same dose of EXONDYS 51: vomiting, bruising, scratches, joint pain, rash, IV site pain, and infections of the upper airways.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088. You may also report side effects to Sarepta Therapeutics at 1-888-SAREPTA (1-888-727-3782).

Please see the full Prescribing Information for EXONDYS 51 (eteplirsen).