Duchenne Muscular Dystrophy (DMD) is a rare progressive disorder. Muscles to become weaker over time until it affects the whole body. Approximately one in every 5.000 boys is born with the disease. It is caused by a mutation on the X-chromosome, this is why only a few girls are affected.
First, walking becomes difficult. Then, other motor functions follow until it ultimately affects the ability to breathe as well as the function of the heart, as the heart is a muscle too. The missing protein also has a function in the brain, so learning- and behavior issues can also be part of the disease.
Duchenne and Becker MD are X-linked recessive disorders. Both conditions are caused by mutations in the dystrophin gene, which encodes the protein dystrophin. A certain part of the DNA is missing, doubled, or changed so the code cannot be read properly by the body.
Males have only one X chromosome copy from their mother and one Y chromosome copy from their father. That is why mainly men and boys are affected. A woman with a genetic change in one of her two copies is said to be ‘a carrier’. However, Duchenne and Becker can occur when the gene mutates spontaneously.
In most countries, the average age of diagnosis of DMD is above 4 years of age and the diagnostic delay around 2.5 years. Parents are seeing symptoms much earlier. Some symptoms are already visible when the children are very young. Lack of awareness of DMD in (first line) health care professionals seeing these children is a major factor that is adding to this delay.
With the current standards of care, people with Duchenne can live into their early 30s and beyond. However, still a certain percentage of boys with DMD die in their late teens, mainly due to cardiac complications. The average life expectancy of people living with Becker is somewhere between 40 and 50 years. With clinical care continuing to improve, as well as clinical trials, research and new therapies, the quality and quantity of life in people living with Duchenne and Becker are enhanced each year.
Depending on a lot of factors including the type of mutation, Duchenne and Becker are different for every person. Even a sibling, having the same mutation, can have a different progression. There are different stages in which Duchenne and Becker people are divided. This is based on whether they are able to walk (ambulant) or not (early loss of ambulation, late loss of ambulation).
Read more about the clinical features and early signs and symptoms of Duchenne and Becker MD.
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