Also called “Duchenne muscular dystrophy”, Duchenne muscular dystrophy is a genetic disease that progressively affects all the muscles of the human body.
Duchenne muscular dystrophy or “Duchenne myopathy” is a genetic and hereditary disease which affects the muscles and does not concern almost like boys. Girls are exceptionally affected. It can affect both skeletal muscles and heart muscle (myocardium). Duchenne muscular dystrophy was first described in 1860 by Doctor Duchenne of Boulogne-sur-Mer. The genetic anomaly is found on a gene on the X chromosome. It is the most common form of childhood progressive myopathy. Its impact is 1 case per 3,300 boy birthsor 150 to 200 potential new cases per year in France, according to the High Authority of Health (HAS). The disease is often undetectable before the age of three.
“The first symptoms may be particular approach of the child, of the falls with difficulty getting up, explains Dr Mélanie Fradin, specialist in clinical genetics. Actions such as climbing stairs are problematic then gradually sets in a difficulty walking requiring the use of a wheelchair. Gradually, the muscles of the trunk and upper limbs also weaken.
“This disease is caused by an abnormality (mutation) of the DMD gene whose main function is to produce dystrophin, continues the doctor. Dystrophin is a protein essential for the integrity of muscle fibers. In the event of a mutation, the protein dystrophin produced is not functional. Without it, the muscle cell membrane is weakened and the fibers are gradually destroyed. Only boys are affected in the vast majority of cases because it is a gene located on the X sex chromosome.
“The diagnosis is based on several examinations, which may include a blood test or muscle biopsy For example, explains the specialist. These examinations are organized by specialized doctors, who generally practice in these reference or competence centers for rare diseases, part of the Filnemus health sector.”
“Treatment is often coordinated by a Physical Medicine and Rehabilitation service, assures Dr. Fradin. It includes a socket in multidisciplinary care. The child generally benefits from physiotherapy.” Treatment with corticosteroids is often offered, the aim of which is to slow down the effects of the disease and prevent some of them. We can also improve daily life thanks to multidisciplinary care adapted to each patient. “For now, no treatment can cure Duchenne muscular dystrophybut many very promising therapeutic trials are underway or planned for 2021, in particular aimed at restoring part of the protein to delay the appearance of symptoms. These include gene therapy trials.” The objective of these treatments is to provide a better quality of life for patients, for as long as possible.
The disease first manifests itself in lower muscles. After a few years, the child no longer has any choice but to use a wheelchair. Its muscle tone in the trunk and arms gradually disappears, leading to complications (risk of bronchopulmonary infections and ventilatory decompensation). Of the tracheotomies are often done to help him breathe. An electric wheelchair can allow him to maintain a certain autonomy of movement.
“Current life expectancy is not known because there are variable forms of Duchenne muscular dystrophy and current treatments gradually modify it but It is a disease that reduces life expectancy and reduces quality of life., concludes the doctor. According to the HAS, more than 90% of affected children live to adulthood. Several studies have demonstrated an average life expectancy of 30 years in patients on assisted ventilation. Some are over the age of 40.
Thanks to Dr Mélanie Fradin, Hospital Practitioner in Clinical Genetics at Rennes Hospital, for her validation.
