Understand Test Results
Meet Nicholas, age 12. Amenable to exon 45 skipping

Understanding genetic testing for Duchenne.

The latest genetic testing methods can identify specific mutations in the dystrophin gene. Identifying your child’s mutation will allow your doctor to determine amenability to AMONDYS 45. Patients with Duchenne who receive AMONDYS 45 must have a genetic test that shows a mutation in the dystrophin gene that can be treated by skipping exon 45.

Getting familiar with genetic test reports.

After your child provides a blood or saliva sample, your doctor will send your child’s genetic sample to a lab to run the genetic test report. Each lab’s report looks a little different. Here are some of the key pieces of information you should be looking for as you read the genetic test report with your child's doctor:

 

  1. A Duchenne diagnosis.

    The genetic test report will identify if there are any mutations in the dystrophin, or DMD, gene that would confirm a Duchenne diagnosis.

    What to look for: A confirmation that there is a mutation on the dystrophin, or DMD, gene. You might see terms like “Positive result,” “Mutation detected,” “Pathogenic variant detected,” or similar terms.
     

  2. The type of mutation.

    The test will provide information on the type of mutation in the dystrophin gene. There are three types of mutations:

    • Large deletions: One or more exons are missing. This is the most common type and includes the ones targeted by AMONDYS 45.
    • Large duplications: One or more exons have extra copies.
    • Other changes: Small changes in the gene that do not include an entire exon.

    What to look for: An indication that the type of mutation is a “deletion.”
     

  3. The missing exons.

    Your child’s doctor or genetic counselor will determine amenability to exon 45 skipping based on which exons are missing. If the genetic test report mentions deletions, it will also identify the “genomic region” or simply add a range of missing exons (e.g., 44).

    What to look for: A number or number range stating which exons make up the deletion.

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Not all genetic tests are created equal. While testing technology has advanced steadily over the last few years, older methods are still in use that may not yield the most accurate results. Ask your child’s doctor to ensure that the lab used for genetic testing employs the latest methods.

Meet Colin, age 11. Amenable to exon 45 skipping

Discuss test results with your child's doctor or genetic counselor.


Whether your child has had a recent test, or you want to reexamine an older one, make sure to review the results with your child's doctor or genetic counselor as soon as possible to determine amenability to AMONDYS 45. In your conversation, you may want to ask:

 

  • Did the test confirm Duchenne muscular dystrophy?
  • What’s the type of genetic mutation?
  • Does my child’s deletion show amenability to exon 45 skipping?
  • Is AMONDYS 45 the right treatment option for us?
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Explore our Doctor Discussion Guide.

It can be a challenge to remember all the information you want to when talking to your doctor. Utilize our helpful guide for information on what to ask during an appointment.
 

Download Our Guide

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Related FAQs

What does “amenable” mean?

Amenability describes the potential for your child to be treated with exon-skipping therapy. AMONDYS 45 is only for those whose Duchenne muscular dystrophy is the result of a genetic mutation amenable to exon 45 skipping. Find out more about genetic testing for Duchenne.

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. Learn more about the role of genetics in Duchenne.

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).