What is Duchenne Muscular Dystrophy (DMD)?
Duchenne Muscular Dystrophy (DMD) is a muscular dystrophy disorder diagnosed in early childhood. According to the National Human Genome Research Institute, it affects about 1 in 3,500 male infants worldwide. DMD is one of a group of progressive muscular disorders, that cause muscle to weaken over time due to a genetic defect.
Who gets DMD?
The defected gene causing DMD can be inherited in families, but it also occurs in people from families without a known history of the condition. Because of the way it is inherited, DMD mostly affects boys. Girls can be born with DMD too, but it is quite rare. Females, however, can be carriers of the altered gene that causes the diseases to occur in their male children.
What happens to children born with DMD?
Children born with DMD typically first show signs of muscle weakness in their leg and pelvic muscles that initially grow large. As the disease progresses, muscle tissue is eventually replaced with fat and connective tissue. Eventually the muscle fibres in the legs shorten making the muscles unusable. By age 12, most boys with DMD can no longer walk and need to use a wheelchair to get around.
Why does DMD occur?
The cells of children with DMD do not produce dystrophin, a protein that helps keep muscle cells growing and working properly. This happens because of a flaw, or mutation, in the gene that is responsible for creating healthy muscles.
What are the symptoms of DMD?
Signs and symptoms usually appear before the age of 6 and may appear as early as infancy. They can include:
- Developmental delay
- Muscle weakness
- Waddling gait
- Difficulty or inability to perform activities such as climbing stairs, running and/or jumping
- Enlarged calf muscles
- Poor standing posture
- Learning difficulties
Kids are usually diagnosed with the disease between the ages of 1 and 6 years. The diagnosis is made after a thorough evaluation and testing by a healthcare team. Noticeable signs can show up any time and may first be noticed when a child cannot sit or stand independently, or is not walking by 18 months.
In older kids, it may show up as trouble running, hopping, jumping, getting up from lying down and walking up stairs. Some boys with DMD have frequent falls or are slower at walking than their peers. Because bones continue to grow normally, there are sometimes skeletal deformities that occur as muscles continue to get weaker.
Why is DMD a life-threatening disease?
Muscles are essential not just for mobility but also for breathing and heart function. So, as DMD advances, the heart and muscles associated with breathing are affected. This can lead to life-threatening situations. Lungs that require strong muscles for healthy functioning may result in difficulty breathing. The disease can affect the heart directly because the heart is also a muscle. Tragically, few individuals with DMD today live beyond their 30s.
What can be done for DMD?
There are no treatments available that can stop or reverse any form of muscular dystrophy. Treatments are aimed at easing the symptoms and improving quality of life. Medications such as corticosteroids, which may slow the loss of muscle mass, may be started when muscles strength starts to decline. Physical therapy is used to promote mobility. Assisted breathing devices are also often used, especially at night. Surgery is sometimes helpful in cases of scoliosis and muscular pain.
Community, advocacy and support groups are important resources for people with DMD, their families and caregivers. Web links to several organisations with helpful resources can be found below.
- 1. Learning about Duchenne Muscular Dystrophy. National Human Genome Research Institute. Accessed 14/2/2017.