Muscular dystrophies are a group of more than 30 inherited diseases that progressively damage muscles. Duchenne muscular dystrophy is the most common and most severe form. It causes weakness in your body’s muscles and mainly affects males.
Although there’s no cure for Duchenne muscular dystrophy, treatments can slow down muscle damage and prevent complications.
How Duchenne muscular dystrophy damages muscles
Muscles are made up of thousands of fibers. When your brain sends out a signal, your muscles contract to help you move. A protein called dystrophin protects muscle fibers from damage as they contract and relax.
The DMD gene holds the instructions for making dystrophin. But when you have Duchenne muscular dystrophy, a mutation (change) to the DMD gene prevents your body from making dystrophin.
Without dystrophin, your muscle fibers become damaged as they contract. Fat and scar tissue replace muscle fibers, and your muscles gradually weaken.
Duchenne muscular dystrophy progresses more quickly than other types of muscular dystrophy.
Males who are born with this condition may not show any symptoms in the first few years of life. However, they are often slower than other kids their age to reach motor-skill milestones such as sitting, standing, and walking.
Muscle weakness usually starts between 3 and 6 years of age. It’s most severe in the legs but can also affect the arms and shoulders. Children with Duchenne muscular dystrophy may walk on their toes, waddle when they walk, have trouble running, and fall a lot because of weak muscles in their legs.
Over time, they may develop contractures (muscle tightening that leaves their joints short and stiff) and scoliosis (a curved spine). Many children with Duchenne muscular dystrophy need to use braces by age 10 and use a wheelchair by age 12.
As the disease progresses, it also weakens muscles in the heart and lungs. Shortness of breath and tiredness are symptoms of cardiomyopathy (a weak heart muscle). Heart problems start during the teen years and can affect people with Duchenne muscular dystrophy by their early 20s.
Treatments for Duchenne muscular dystrophy help manage the symptoms and improve quality of life, but they don’t cure the disease.
Corticosteroids such as prednisone can slow down muscle damage and cardiomyopathy. These medications can help people keep walking for 2 to 3 years longer. High blood pressure medications such as angiotensin-converting enzyme (ACE) inhibitors, diuretics, and beta-blockers can also help manage cardiomyopathy.
Physical therapy treatments such as stretching and braces can help prevent contractures. Some people need surgery to treat contractures or scoliosis.
The Food and Drug Administration (FDA) has approved some newer medications for Duchenne muscular dystrophy. These medications are for people who have DMD mutations that allow their body to skip a specific exon (part of the gene) when it reads the instructions to make the dystrophin protein. These medications are given as infusions (injections into a vein over time).
Eteplirsen 51 (Exondys 51) is FDA-approved for children 4 and 5 years old who have a DMD mutation that can skip exon 51. About 13% of people with Duchenne muscular dystrophy have this gene mutation. The protein that Exondys 51 produces is shorter than usual, but it can relieve some symptoms of the disease.
Golodirsen (Vyondys 53) and viltolarsen (Viltepso) are approved for people with a DMD mutation that can skip exon 53. About 8% of people with Duchenne muscular dystrophy have this gene variant.
Casimersen (Amondys 45) is approved for people with a DMD mutation that can skip exon 45. This includes about 8% of people with Duchenne muscular dystrophy.
Possible side effects of these new treatments include:
- cough and cold
- fever
- headache
- nausea and vomiting
Delandistrogene moxeparvovec-rokl (Elevidys) is a new gene therapy for Duchenne muscular dystrophy. It’s FDA-approved for children 4 to 5 years old who have a mutation in the DMD gene. Elevidys comes as an infusion. An inactivated virus delivers a gene that helps the child’s body produce a shorter version of the dystrophin protein.
Researchers are studying other new treatments for Duchenne muscular dystrophy in clinical trials. People who enroll in one of these studies may have the chance to try a new medication before it’s available to everyone else.
If you have a family history of Duchenne muscular dystrophy, talk with your doctor about genetic testing. Although there is no cure, new treatment options are helping people with this disease explore new options. Working with a genetic specialist is the first step in understanding your risk for Duchenne muscular dystrophy and making informed health decisions.