Duchenne Muscular Dystrophy

What is Duchenne muscular dystrophy?

Duchenne muscular dystrophy is a genetic (inherited) condition that causes the muscles to weaken and waste away over time. It is the most common and one of the most severe forms of muscular dystrophy, a group of disorders in which muscle fibers gradually break down. The condition is caused by a fault in the gene that tells the body how to make dystrophin, a protein that helps keep muscle cells strong and intact. Without enough working dystrophin, muscle fibers are damaged each time they contract and are slowly replaced by fat and scar tissue.

Duchenne muscular dystrophy affects mostly boys. This is because the faulty gene sits on the X chromosome, and boys have only one X chromosome. Girls can carry the gene change and occasionally have mild symptoms, but they are rarely severely affected. Signs usually appear in early childhood, often between about two and five years of age, and the weakness progresses through childhood and adolescence. It is a lifelong condition that eventually affects the heart and breathing muscles as well as the muscles used for movement. Care is usually coordinated by a neurology team working alongside heart, lung, orthopedic and rehabilitation specialists. At Acibadem, this condition is managed by the Neurology department together with related units.

Duchenne muscular dystrophy symptoms

Duchenne muscular dystrophy symptoms usually begin in the large muscles of the hips, thighs and shoulders and then spread to other parts of the body. Early on, parents may simply notice that their child is a little slower or clumsier than other children of the same age. Common features include:

• Delayed walking, often not walking independently until after 15 to 18 months
• Frequent falls and difficulty running, jumping or climbing stairs
• A waddling walk, or walking on the toes
• Difficulty getting up from the floor, often using the hands to “climb” up the legs (called the Gowers sign)
• Enlarged calf muscles that feel firm (this is because damaged muscle is replaced by other tissue)
• Tiredness and reluctance to walk long distances
• Learning, speech or behavioral difficulties in some children
• Curvature of the spine (scoliosis) as the condition progresses
• Heart and breathing problems in the teenage years and beyond

The symptoms change as the condition moves through different stages. In the early ambulatory stage, children can still walk but tire easily and struggle with stairs. In the late ambulatory stage, usually in the later primary-school years, walking becomes harder and many children begin to need a wheelchair for longer distances. Most boys with Duchenne muscular dystrophy lose the ability to walk in early adolescence. In the non-ambulatory stages, arm and hand strength declines, the spine may curve, and the muscles that control breathing and the heart muscle itself are increasingly affected. Cardiomyopathy, a weakening of the heart muscle, and breathing difficulties, particularly at night, become important concerns.

Not every child follows the same timeline. Some children keep walking longer than others, and treatment, especially with corticosteroids, may slow the pace of decline in many cases. A milder related condition called Becker muscular dystrophy involves the same gene but produces some partially working dystrophin, so symptoms start later and progress more slowly.

Causes and risk factors

Duchenne muscular dystrophy causes are genetic. The condition results from a change, known as a mutation, in the DMD gene on the X chromosome. This gene is one of the largest in the human body and provides the instructions for making dystrophin. In Duchenne muscular dystrophy, the mutation means that little or no functional dystrophin is produced. Dystrophin normally acts like a shock absorber, anchoring the inside of the muscle cell to its outer membrane. Without it, the membrane becomes leaky and fragile, and muscle fibers are progressively destroyed.

Several types of gene changes can cause the condition, including deletions (missing sections of the gene), duplications (extra copies of sections) and small changes in the genetic code. The specific type of mutation matters, because some newer treatments are designed for particular mutations.

The main risk factors relate to inheritance:

• Being male: boys have one X chromosome, so a single faulty copy of the gene causes the condition.
• Family history: the condition is inherited in an X-linked pattern, meaning a mother who carries the gene change can pass it to her children. Each son of a carrier mother has a one in two chance of being affected, and each daughter has a one in two chance of being a carrier.
• New mutations: in roughly one third of cases, there is no family history because the gene change happens for the first time in the affected child or in the mother’s egg cell.

Female carriers usually have no significant muscle symptoms, but some develop mild weakness or heart muscle problems later in life, so carriers are often advised to have periodic heart checks. Duchenne muscular dystrophy is not caused by anything a parent did or did not do during pregnancy, and it is not contagious.

Diagnosis

Duchenne muscular dystrophy diagnosis usually begins when a parent, pediatrician or teacher notices motor delays or unusual walking. The doctor will ask about developmental milestones and family history and will examine the child’s strength, reflexes, walking pattern and muscle size.

The first test is often a simple blood test for creatine kinase (CK), an enzyme that leaks out of damaged muscle. In Duchenne muscular dystrophy, CK levels are typically very high, often many times above normal, even before symptoms are obvious. A very high CK level in a young boy with weakness strongly suggests a muscular dystrophy and prompts further testing. Liver enzymes measured in routine blood tests may also be raised, because these enzymes are also released from muscle.

The diagnosis is confirmed with genetic testing. A blood sample is analyzed to look for deletions, duplications or smaller changes in the DMD gene. Modern genetic tests identify the causative mutation in the great majority of affected children. Knowing the exact mutation helps doctors advise on prognosis, identify which family members may be carriers and decide whether mutation-specific therapies might be an option.

Other tests your doctor may use include:

• Muscle biopsy: a small sample of muscle is removed and examined for the presence and amount of dystrophin. This is now needed less often because genetic testing is so accurate, but it may be used when genetic results are unclear.
• Electromyography (EMG): a test that measures the electrical activity of muscles, which can help distinguish muscle disease from nerve disease.
• Heart tests: an electrocardiogram (ECG), which records the heart’s electrical rhythm, and an echocardiogram or cardiac MRI, which show how well the heart muscle is pumping. These are usually done at diagnosis and repeated regularly.
• Lung function tests: breathing tests that measure how strong the breathing muscles are; these become more important as children get older.
• Genetic counseling and carrier testing: offered to mothers and other female relatives to clarify the risk to future pregnancies.

Because early treatment may help preserve function, doctors generally aim to confirm the diagnosis as soon as possible once it is suspected. Some regions are studying newborn screening for the condition, but it is not yet routine everywhere.

Duchenne muscular dystrophy treatment options

There is currently no cure for Duchenne muscular dystrophy. However, treatment has improved considerably, and coordinated care from a multidisciplinary team can slow the progression of weakness, prevent or delay complications and support quality of life. Duchenne muscular dystrophy treatment is tailored to the stage of the condition and to the individual child and family.

Medication. Corticosteroids, such as prednisone or deflazacort, are the mainstay of drug treatment. In many cases they help children walk for longer, preserve arm and breathing muscle strength and reduce the risk of scoliosis. They are usually started while the child is still walking. Long-term steroid use has side effects, including weight gain, slowed growth, weakened bones, mood changes and cataracts, so doctors monitor children closely and may adjust the dose. Newer medications called exon-skipping drugs have been approved in some countries for children with specific mutations; they aim to help the body make a shortened but partly working form of dystrophin. Gene therapy, which delivers a smaller version of the dystrophin gene into muscle cells, has also become available in some settings for certain age groups. These therapies are not suitable for everyone, their long-term benefits are still being studied, and eligibility depends on the exact mutation and other factors. Your doctor can explain whether any of these options apply.

Heart care. Because the heart muscle is affected, cardiologists usually begin heart-protective medicines, such as ACE inhibitors or beta blockers, either when early changes appear on heart scans or, in some care protocols, before symptoms develop. Regular heart imaging continues throughout life.

Breathing support. As the breathing muscles weaken, people may need help clearing secretions and, later, breathing support. This often begins with a non-invasive ventilator (a mask connected to a machine) used at night and may progress to daytime use. Vaccination against influenza and pneumonia is generally recommended.

Rehabilitation and therapy. Physical therapy focuses on gentle stretching to prevent contractures, which are permanent tightening of muscles and tendons, especially at the ankles, knees and hips. Night splints, standing frames and appropriate low-impact activity such as swimming are commonly advised, while very strenuous exercise is usually avoided because it may accelerate muscle damage. Occupational therapy helps with daily tasks, school participation and equipment such as wheelchairs, hoists and adapted vehicles. Speech and language therapy and educational support may be needed for children with learning or communication difficulties.

Surgery and orthopedic care. Some children benefit from surgery to release tight tendons and improve positioning. Spinal fusion surgery may be recommended for significant scoliosis to maintain comfortable sitting and protect breathing. Bone health is monitored because steroids and reduced weight bearing increase the risk of fractures; vitamin D, calcium and sometimes bone-strengthening medicines are used.

Nutrition and general health. Dietitians help manage weight, which can rise with steroids and reduced activity or fall later when chewing and swallowing become harder. Constipation, reflux and swallowing difficulties are addressed as they arise. Psychological support for the child and family is an important part of care at every stage.

Observation alone is not appropriate for Duchenne muscular dystrophy, because the condition is progressive and complications can be anticipated. Instead, care follows a schedule of regular reviews so that treatments are introduced at the right time.

Living with Duchenne muscular dystrophy and outlook

Duchenne muscular dystrophy is a life-limiting condition, and it is important to be honest about this. Historically, many young men did not survive beyond their late teens, mainly because of heart and breathing complications. With modern coordinated care, including steroids, heart medication, ventilation support and spinal surgery, many people now live into their thirties and sometimes beyond. Outcomes vary widely between individuals, and no doctor can predict exactly how the condition will progress in a particular person.

Day-to-day life involves adapting as needs change. Children usually attend mainstream school with support, and adaptations at home such as ramps, accessible bathrooms and hoists become necessary over time. Many young adults with the condition pursue further education, work and independent living with personal assistance. Planning ahead for transitions, such as moving from children’s to adult services, helps avoid gaps in care.

Emotional wellbeing matters for the whole family. Parents often experience grief at diagnosis and again at each stage of progression, and siblings may also need support. Peer support groups and patient organizations can be valuable sources of practical advice. Genetic counseling helps families understand recurrence risks and options for future pregnancies.

Research is active, and clinical trials of new therapies are ongoing. While these offer hope, it is wise to be cautious about claims of cures, and to discuss any experimental treatment with the medical team before making decisions.

Frequently asked questions

What are the first signs of Duchenne muscular dystrophy symptoms in toddlers?

The earliest signs are often subtle. Parents may notice late walking, frequent falls, difficulty climbing stairs, trouble getting up from the floor, a waddling gait or unusually large calves. Some children also have speech delay. These signs can have many causes, so a child with these features should be assessed by a doctor, who may check a creatine kinase blood level as a first step.

What are the main Duchenne muscular dystrophy causes, and can girls get it?

The condition is caused by mutations in the DMD gene on the X chromosome, leading to a lack of the protein dystrophin. Because boys have only one X chromosome, they are affected far more often. Girls who carry the gene change usually have no or mild symptoms, though a small number develop weakness or heart problems, which is why carriers are often offered heart monitoring.

How is Duchenne muscular dystrophy diagnosis confirmed?

Diagnosis usually starts with a blood test showing a very high creatine kinase level. It is then confirmed by genetic testing that identifies a mutation in the DMD gene. A muscle biopsy is sometimes used if genetic results are inconclusive. Heart and lung tests are performed at diagnosis to establish a baseline for ongoing monitoring.

Is there a cure, and what does Duchenne muscular dystrophy treatment involve?

There is no cure at present. Treatment combines corticosteroids to slow muscle weakening, heart-protective medicines, physical therapy to prevent contractures, breathing support when needed, orthopedic care for the spine and joints, and nutritional and psychological support. Newer gene-based therapies are available in some countries for specific mutations, but their long-term effects are still being studied.

Can adults be diagnosed with Duchenne muscular dystrophy?

Duchenne muscular dystrophy almost always causes obvious symptoms in early childhood, so a first diagnosis in adulthood is unusual. Adults who develop slowly progressive weakness related to the same gene are more likely to have Becker muscular dystrophy, a milder form in which some dystrophin is still produced. Genetic testing can distinguish between the two.

Does exercise help or harm in Duchenne muscular dystrophy?

Gentle, regular activity such as swimming, cycling on a stationary bike or supervised stretching is generally encouraged to maintain flexibility and general health. High-resistance strength training and exercise to the point of exhaustion are usually discouraged because fragile muscle fibers may be damaged further. A physical therapist familiar with the condition can advise on a safe program.

What is the life expectancy for someone with Duchenne muscular dystrophy?

Life expectancy has increased with modern care, and many people now live into adulthood, often into their thirties and sometimes longer. Outcomes depend on how well heart and breathing complications are managed and vary from person to person. The medical team can discuss what the outlook may mean for an individual, but precise predictions are not possible.

When to see a doctor

Parents should arrange a medical assessment if a child is not walking by about 18 months, falls frequently, struggles to climb stairs or rise from the floor, walks on the toes or with a waddle, or has unusually large, firm calf muscles. Any boy with a family history of Duchenne or Becker muscular dystrophy and new weakness should be evaluated promptly, and a pediatrician or neurologist can arrange the appropriate tests.

For people already diagnosed, the following warning signs need urgent medical attention:

• Shortness of breath at rest, rapid or labored breathing, or a bluish tinge to the lips
• New or worsening morning headaches, daytime sleepiness or frequent waking at night, which may indicate breathing problems during sleep
• Chest pain, a racing or irregular heartbeat, fainting or new swelling of the legs or abdomen
• Persistent cough, fever or a chest infection that is not improving, since weak breathing muscles make pneumonia more dangerous
• A fall or injury with severe pain, swelling or inability to move a limb, as fractures are more likely
• Sudden inability to swallow, choking on food or fluids, or repeated vomiting
• Severe abdominal pain or bloating, or no bowel movement for several days
• Sudden confusion, unusual drowsiness or a marked change in behavior, especially in a child taking corticosteroids who is unwell or has missed doses

People taking long-term corticosteroids should never stop them suddenly, and the medical team should be told about any illness, surgery or injury so that steroid doses can be adjusted safely. Any anesthesia or surgery should be planned with a team aware of the diagnosis, because certain anesthetic drugs carry additional risks in people with Duchenne muscular dystrophy.