If the DMD gene is out of tune, it can affect the whole performance.1
But with gene therapy, it may one day achieve better harmony.1
/assets/images/media_13937c68c2d3625663c36c0fa53147fc8104db960.png
Reimagine Duchenne is an invitation to learn more
about the potential of gene therapy. Gene therapy is
being studied to add some of the functional protein
children with Duchenne muscular dystrophy need.1
assets/images/media_12baca7094c49e49713f067e05bd98f41cc9aa0c4.png
Understanding the types of DMD gene mutations
The DMD gene is the body's longest gene.6 A mutation to any part of this gene can lead to Duchenne.1,4 A deletion mutation is most common in Duchenne.1 There are two types of deletion mutations, in-frame and out-of-frame. If a deletion is in-frame, the DMD gene is maintained and not disrupted, which means it is present but is shorter than normal.1,4 An out-of-frame deletion is when part of the DMD gene is missing. An out-of-frame deletion can lead to Duchenne.1,4 Duplication mutations, where part of the gene is repeated, can also cause Duchenne.3 Deletion mutations and duplication mutations account for 70-80% of Duchenne cases.3 Other cases are caused by a point mutation, which impacts a very small portion of a part of the DMD gene.3
See below for visual examples of the different types of mutations in the DMD gene:
Who does Duchenne affect?
The different stages of Duchenne
and how it’s diagnosed
Recognizing the signs, symptoms, and progression of Duchenne
The progression of Duchenne may vary from child to child. Early on, the impact of muscle weakness may be limited to movement and walking. Over time, muscle damage builds, and continued loss of muscle then impacts more of the body, including the heart and the muscles that affect how the lungs function.9,10
One early sign that is common to Duchenne is Gowers' sign.1 This is when the child rises from the floor by starting on their hands and knees and then "walking" their hands up their legs. Read on for some other potential signs of Duchenne over time.1
Early stage
0+ years old*10
Pre-symptomatic/ diagnosis10
- Show delays in milestones like crawling, walking, or talking10
- Large calves11
- Have raised creatine kinase (CK) or creatine kinase-MM (CK-MM) levels and/or liver enzymes found on blood test10
- Falling often11
- Gowers’ sign1
Middle stage
8+ years old*10,11
Ambulatory
(able to walk independently)10,11
- Leg muscle aches10
- Having trouble walking12
- Losing ability to climb stairs and stand up from the floor10
- Achilles tendon tightening known as a contracture11
Late stage
12+ years old*10,11
Non-ambulatory
(no longer walking independently)10,11
- Increasing loss of upper limb function10
- Not able to maintain posture10
- Develop scoliosis, a curve in the spine11
- Function in the lungs is declining and may need breathing assistance11
- Function in the heart is declining11
*Ages and stages may vary depending on each child.
Duchenne testing – at diagnosis and over time
Diagnosis is based on key signs, medical history, and several tests.
Blood tests
- Creatine kinase-MM test – A test that looks for high levels of CK-MM in the blood, which can signal muscle damage. By itself, a high CK-MM level is not enough to know for sure if a child has Duchenne, as there can be other causes for this.1,9
- Genetic test – A test used to confirm the presence and type of DMD gene mutation. Genetic testing can be done at any point in the diagnosis journey.9,10
Muscle biopsy
If signs, history, and blood tests (including genetic testing) are not enough to make a diagnosis, a muscle biopsy may be needed. For this procedure, the doctor will remove a very small amount of the muscle to test if it has dystrophin. The doctor will then use the results to confirm the diagnosis.9
Finding a team of specialists is a key step when caring for a child with Duchenne.10
A neuromuscular specialist helps understand nerve and muscle diseases. This specialist usually makes the diagnosis of Duchenne and leads the care team. The care team provides all-around care for children living with Duchenne and may recommend other specialists.9
Duchenne can also affect the heart and how the lungs function. That’s why both a pulmonologist and a cardiologist may be part of the care team. Other care team members may include a primary care doctor, a physical therapist, an occupational therapist, and others.10
The care team will track Duchenne over time with a series of functional tests
The care team for a child living with Duchenne will track how their symptoms change over time. To do this, a neuromuscular specialist or a physical therapist may use special tests to assess the impact of Duchenne and the child's ability to move.10,13 These tests may include the North Star Ambulatory Assessment (NSAA), the 6-minute walk test (6MWT), the 10-meter walk test (10MWT), and the timed rise from floor test (TRF).13,14,15 These tests are commonly used by physicians to measure functional motor abilities.9
It is important for the care team to keep track of a child's progress so they can monitor any changes to see if they need additional support.
For illustration purposes only.
Example NSAA Test: Jump
NSAA tracks changes in 17 key movements12
The NSAA includes 17 tests to measure functional skills.12 These include sitting, standing, walking, jumping, and getting up from a chair. A member of the care team will grade each test with a score from 0-2. These scores are based on whether the child can perform the movement and how well they can do it.12 A child with Duchenne may show improvements in their score due to either the natural course of disease or due to treatment.16,17
For illustration purposes only.
Example Test: 6-minute walk test
Walking tests help track endurance and assess loss of gait18,19
A care team member will use the 6-minute walk test (6MWT) to assess the distance a child with Duchenne can walk within 6 minutes.13 After the test is performed, the doctor can track the progression of muscle function as well as the child's endurance.18
The 10-meter walk test (10MWT) may be used to evaluate the time it takes for a child with Duchenne to walk 10 meters.15 This test can help the doctor measure the child's manner of walking, known as their "gait," over time.19
For illustration purposes only.
Example Test: Timed rise from floor test
The timed rise from floor test (TRF) helps track the progression of Duchenne14
The timed rise from floor test measures the time it takes a child lying face-up to stand.14 It is often performed at the same time as the NSAA test.14 The child will only be timed if they are able to complete this test. The TRF test helps the care team track the child's movement and disease progression over time.14
Science and medicine are evolving the care of Duchenne
The care team approach has improved the length and quality of life for children living with Duchenne.9
Learn how an out-of-tune DMD gene can affect the whole performance
