Understanding Duchenne
Meet Nicholas, age 12. Amenable to exon 45 skipping

Gaining a deeper understanding of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) or “Duchenne” is a rare genetic disease that affects mostly boys. Duchenne is caused by a mutation in the gene that’s responsible for the body’s production of dystrophin, a protein that enables muscles to function properly. This mutation causes dystrophin production to be reduced or shut down so muscles become damaged and weaken over time.

The numbers behind Duchenne.

~5 years old The average age a child is diagnosed.
1 in 3,500 to 5,000 Occurrence in boys born each year.
2.5 years Average number of years from initial symptoms to diagnosis.

What is dystrophin?

A protein muscles need to work properly. It helps protect the cells in our muscles as we use them. When you don't have enough or any dystrophin, muscles can become damaged and weak. Learn how exon skipping works.

Graphic of a dystrophin gene

Duchenne muscular dystrophy symptoms.

Children with Duchenne experience developmental delays that may mimic symptoms of other disorders, but the telltale symptoms of Duchenne point to underlying muscle weakness. Parents may first notice that their child isn’t walking by 16-18 months of age or is displaying other common symptoms such as:

 

  • An unsteady or waddling gait 
  • Frequent falls 
  • Large calves compared to others their age  
  • Using their arms to walk the torso to a standing position (Gowers' maneuver or Gowers' sign)
  • Walking on their toes 
  • Difficulty running or climbing stairs 
  • Delays in speech 
  • Behavior and learning disorders

While these symptoms alone will not confirm a Duchenne diagnosis, they may warrant a visit to your child’s doctor to discuss next steps, including whether a blood test to check their creatine kinase (CK) level is appropriate. To learn more about Duchenne signs and symptoms, visit Parent Project Muscular Dystrophy.

Meet Levi, age 10. Amenable to exon 45 skipping

Disease progression.

Duchenne is a progressive disease that weakens muscles. Children with Duchenne go through similar phases, but the rate of progression varies. Because Duchenne affects so many muscles, its signs and symptoms become more widespread throughout the body.

Early phase—In the early phase of Duchenne—through infancy and childhood—a child may have difficulty with typical developmental milestones, such as sitting, walking, or talking.

Transitional phase—As they transition into the later stage of childhood, the child’s hip and leg muscles become weaker and they will have trouble climbing stairs, running, and keeping up with other children. They often walk their hands up their legs to rise from the floor to a standing position—a sign of Duchenne that is commonly known as “Gowers' maneuver.”

Loss of ambulation—As a child with Duchenne moves into their teen years and muscle strength continues to decline, they tire more easily and may become reliant on a wheelchair. They typically have use of their arms and hands but muscle weakness often leads to difficulties in carrying things like schoolbooks.

Adult phase—Adults with Duchenne experience further decline in muscle function, including the heart and breathing muscles. Breathing becomes increasingly difficult and there may be a greater likelihood of life-threatening heart and lung conditions.

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Time is of the essence. It's vital that every child gets a genetic test to identify their specific genetic mutation.

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Related FAQs

Why is a Duchenne diagnosis important?

Because Duchenne is a progressive disease, it’s important for your child's doctor to confirm a diagnosis and identify the specific genetic mutation to guide your child's care and treatment. More about the steps to diagnosis.

Read More

 

What is AMONDYS 45 (casimersen)?

AMONDYS 45 is used to treat patients with Duchenne muscular dystrophy (DMD) who have a confirmed mutation of the dystrophin gene that can be treated by skipping exon 45.

This indication is approved under accelerated approval based on an increase in dystrophin production in skeletal muscle observed in patients treated with AMONDYS 45. Continued approval for this indication may be contingent upon verification of a clinical benefit in confirmatory trials.

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IMPORTANT SAFETY INFORMATION

Contraindications: Do not receive AMONDYS 45 if you are allergic to casimersen or any of the ingredients in AMONDYS 45. Serious allergic reactions to casimersen have included anaphylaxis, which may include difficulty breathing, tightness in the chest, and angioedema which may include swelling of the mouth, face, lips, or tongue.

Hypersensitivity Reactions: Serious allergic reactions, including angioedema and anaphylaxis, have occurred in patients who were treated with AMONDYS 45. Patients should seek immediate medical care should they experience signs and symptoms of allergic reactions. Your doctor will institute appropriate medical treatment which may include slowing, interrupting, or discontinuing the AMONDYS 45 infusion. Your doctor will monitor you until the condition resolves.

Kidney Toxicity and Monitoring: Damage to the kidneys was seen in animals who received casimersen. Although damage to the kidneys was not seen in clinical studies with AMONDYS 45, potentially fatal kidney damage has occurred with other drugs that work in a similar way. Your doctor may recommend urine and blood testing before starting treatment followed by urine testing every month and a blood test every 3 months to monitor your kidneys.

Adverse Reactions: Side effects occurring in at least 20% of patients treated with AMONDYS 45 and at least 5% more frequently than in patients who received an inactive intravenous (IV) infusion were (AMONDYS 45, placebo): upper respiratory tract infection (65%, 55%), cough (33%, 26%), fever (33%, 23%), headache (32%, 19%), joint pain (21%, 10%), and pain in mouth and throat (21%, 7%).

Other side effects that occurred in at least 10% of patients treated with AMONDYS 45 and at least 5% more frequently than patients who received an inactive IV infusion were: ear pain, nausea, ear infection, pain after injury, and dizziness and light-headedness.

What do I do if I have side effects?

Ask your healthcare provider for advice about any side effects that concern you.

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).

The information provided here does not include all that is known about AMONDYS 45. To learn more, talk with your healthcare provider.

Before receiving this infusion, please see the full Prescribing Information for AMONDYS 45 (casimersen).