Duchenne muscular dystrophy (DMD) is a type of muscular dystrophy that appears during childhood, usually between the ages of three and five. It is caused by the mutation of a gene, DMD, which encodes dystrophin, a protein that helps strengthen muscle fibers and protects them against injuries. It causes dependency and limits the years of life. It affects one in every 3,500 boys in the world, although it can also affect girls.
Causes of Duchenne muscular dystrophy
Mutation in a gene on the X chromosome
Duchenne muscular dystrophy is caused by a defect in the DMD gene, which is located on the muscle cells. Without this protein, muscles do not function correctly, suffering rapid and progressive degeneration until they die. The destroyed muscle cells are replaced by connective (fibrotic) tissue that causes contractures and muscle stiffness.
Among the substances that escape from the interior of the muscle cell into the bloodstream, the release of creatine kinase or creatine phosphokinase (CPK) stands out, which participates in the production of energy that the muscle requires for its proper functioning. CPK increases its value in the blood by 10 to 100 times (the normal value is 0 to 200).
Cases of Duchenne muscular dystrophy are usually hereditary, usually from mothers who are carriers of the disease, but it can also occur by spontaneous mutation in families with no known history of the pathology.
Symptoms of Duchenne muscular dystrophy
Frequent falls from early childhood
Signs and symptoms usually appear in boys between the ages of three and five and progress rapidly. At twelve years old they usually need a wheelchair. The first symptoms are:
– Frequent falls.
– Weakness in the muscles near the trunk and pelvis. Difficulty getting up from a horizontal position or when sitting.
– Problems running and jumping.
– Duck walk.
– Calves with large muscles due to fat accumulation.
– Muscle pain and stiffness.
– Learning difficulty.
– Symptoms that may appear as the disease progresses.
– Difficulty breathing.
– Weakness of the heart muscle.
– Fatigue and inflammation of the feet.
– Respiratory problems due to weakness in the respiratory muscles.
– Swallowing problems that can lead to aspiration pneumonia.
– Scoliosis.
Diagnosis of Duchenne muscular dystrophy
Physical exam and blood tests
The specialist may suspect a case of Duchenne muscular dystrophy when there is weakness in the upper legs and pelvis. One test is that the patient has to rise from a squatting position using his hands and arms, which indicates a lack of muscle strength in the hips and thighs.
A blood test can confirm an elevated presence of creatine kinase in the blood and also aspartate transaminase and alanine transaminase. At this point the patient is usually referred to a neurologist. The rest of the diagnostic confirmation tests are:
– Electromyography.
– Muscle biopsy.
– Genetic examination.
Duchenne muscular dystrophy treatment and medication
Symptom control
There is no specific treatment for DMD, so treatment focuses on treating and controlling symptoms and improving the patient’s quality of life. Treatment and follow-up must be multidisciplinary and include:
– Physiotherapy.
– Speech therapy.
– Hydrotherapy.
– Equine therapy.
– Nutrition program.
– Assessments of muscle strength and range of motion.
– Orthopedic solutions to improve the ability to move, such as crutches and wheelchairs.
– Evaluation of respiratory function.
– Aid devices to reduce breathing difficulties, especially at night.
– Evaluation of cardiac function.
At a pharmacological level, Eteplirsen may be the option for the treatment of some forms of DMD. The standard of care is corticosteroids such as prednisone or deflazacort, which reduce inflammation and help improve muscle strength and function. When dilated cardiomyopathy (large, weak heart) appears, there is medication and, in severe cases, a heart transplant may be considered.
Prevention of Duchenne muscular dystrophy
Without prevention
There are no preventive measures against DMD but maintaining adequate nutrition, with high fiber and protein content, prevents obesity, dehydration and constipation.
Your exercise program may want to include low-impact aerobic exercise such as walking or swimming and range-of-motion exercises to improve joint flexibility.
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