Duchenne muscular dystrophy, sometimes shortened to DMD or just Duchenne, is a rare genetic disease. It primarily affects males, but, in rare cases, can also affect females. Duchenne causes the muscles in the body to become weak and damaged over time, and is eventually fatal. The genetic change that causes Duchenne — a mutation in the DMD gene — happens before birth and can be inherited, or new mutations in the gene can occur spontaneously.
The cause of Duchenne
Duchenne is caused by a genetic mutation that prevents the body from producing dystrophin, a protein that muscles need to work properly. Without dystrophin, muscle cells become damaged and weaken. Over time, children with Duchenne will develop problems walking and breathing, and eventually the muscles that help them breathe and the heart will stop working. Duchenne is an irreversible, progressive disease. There is currently no cure for Duchenne.
What happens in Duchenne?
Duchenne is caused by mutations to the dystrophin gene. Most commonly, one or more exons (a portion of the gene) are missing, and the remaining exons don’t fit together properly. Because of this error in the genetic instructions, cells cannot make dystrophin, a protein muscles need to work properly. Without dystrophin, muscle cells are damaged, and, over time, are replaced with scar tissue and fat in a process called fibrosis.Types of mutations include:Large deletions: One or more exons are missing from the dystrophin gene
Large duplications: One or more exons have extra copies in the dystrophin gene
Other changes: Small changes, such as tiny deletions or changes in a single letter in the instructions
72% large deletions
7% large duplications
The most common mutation in people with Duchenne is a deletion of one or more exons. Much like a puzzle, these missing pieces prevent the remaining exons from fitting together properly.This causes errors in the instructions for making dystrophin, and the body is not able to produce a working dystrophin protein.When exons do not fit together Dystrophin protein cannot be created
The first signs and symptoms of Duchenne are often noticed around the age of 2 or 3. Children with Duchenne may be slower to sit, stand or walk. Most are unable to run and jump properly due to weakness in the core muscles of the body.
Common signs and symptoms of Duchenne you may notice:
Not walking until approximately 18 months of age
Walking on toes with legs apart, walking with the belly pointed out, or both
Falling down often
Needing help getting up from the floor or using arms to “walk” the body to a standing position (Gower’s maneuver)
Larger calves than other children of the same age or size
Behavior and learning problems
Duchenne's effect on the brain
Children with Duchenne are more likely to have conditions affecting the brain, such as mental health, learning, or seizure disorders. The key protein for muscle function that is missing in Duchenne, dystrophin, is also believed to have a role in brain development. In children with Duchenne, the lack of dystrophin is believed to affect the ability of certain brain cells, called neurons, to connect properly and share information
This can lead to challenges with important brain functions such as attention, memory, learning, speech, and intellectual ability
A higher risk of ADHD, ASD, and OCD
Children with Duchenne are more likely to have such conditions as attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASD), learning disorders such as dyslexia, and obsessive-compulsive disorder (OCD)
In addition, abnormal electrical activity in the brain makes children with Duchenne more prone to developing epilepsy (seizures)
Duchenne by the numbers
One of the most serious genetic diseases in children worldwide
Occurs in 1 in 3,500 to 5,000 males born worldwide
Duchenne muscular dystrophy usually affects males. However, females are also affected in rare instances. Approximately 8% of female Duchenne muscular dystrophy (DMD) carriers are manifesting carriers and have muscle weakness to some extent.
5 is the Average age of diagnosis
Time from initial symptoms to diagnosis is 2.5 years