Congenital Muscular Dystrophy (CMD)

What is congenital muscular dystrophy?

Congenital muscular dystrophy (CMD) refers to a group of muscular dystrophies that become apparent at or near birth. “Congenital” means “present from birth.”

Muscular dystrophies are chronic genetic (inherited) conditions that cause muscle weakness and other symptoms. Muscle weakness generally becomes more severe over time.

Types of congenital muscular dystrophies

There are several subtypes of congenital muscular dystrophy. Healthcare providers diagnose the subtype according to the affected gene(s). Some of the most common include:

• Laminin-alpha 2-related dystrophies (LAMA2): These represent 10% to 37% of CMD cases. Children with early-onset LAMA2-related muscular dystrophy often don’t develop the ability to walk. They may also have difficulty with speech due to weakness of their facial muscles and an enlarged tongue (macroglossia). Seizures affect about one-third of children with this condition.
• Dystroglycanopathies (DGPs): These represent 12% to 25% of CMD cases. In addition to muscle weakness, DPGs often affect your child’s brain, causing seizures and cognitive disabilities. They can cause eye issues as well. Additional types within this subgroup include Walker-Warburg syndrome, muscle-eye-brain disease and Fukuyama CMD (FCMD). FCMD is the most common form of CMD in Japan.
• Collagen VI-related dystrophies (COL6-RDs): These represent 12% to 19% of CMD cases. Additional types within this subgroup, ranging from mild to severe, include Bethlem muscular dystrophy, intermediate COL6-RD and Ullrich congenital muscular dystrophy (UCMD).
• Selenoprotein N-related myopathies (SEPN1-RM): These represent about 11% of CMD cases. They involve early-onset muscle weakness that affects axial (head and trunk) muscles. This leads to early respiratory insufficiency.

How common is congenital muscular dystrophy?

Congenital muscular dystrophy is rare. Researchers estimate that it affects 6 to 9 children per 1 million worldwide.

What are the symptoms of congenital muscular dystrophy?

The main symptom of congenital muscular dystrophy is muscle weakness. At birth or shortly thereafter, this could look like:

• Poor muscle tone (hypotonia). People sometimes call this “floppy infant syndrome.”
• Minimal spontaneous movements of arms and legs.
• A weak cry.
• Feeding difficulties (due to a weakened suck mechanism).
• Muscle and joint tightness (contractures).

Significant gross motor skill delays in child development are also signs of CMD later after birth.

The severity of muscle weakness and other symptoms in babies with CMD can vary. Depending on the specific type of CMD, your child may have additional symptoms, like:

• Eye issues, like myopia (nearsightedness) and glaucoma.
• Drooping upper eyelid (ptosis).
• Brain abnormalities, like lissencephaly or cerebellar malformations.
• Seizures.
• Intellectual disability.

What are the complications of congenital muscular dystrophy?

The possible complications of congenital muscular dystrophy depend on the type. But in general, they could include:

• Mobility issues: Some children with CMD may not develop the ability to walk and may need a wheelchair. Others may need to use assistive devices, like orthopaedic braces or a walker to help them with mobility.
• Respiratory complications: A relatively common complication of CMD is chronic respiratory failure, which can develop due to weakness of the muscles your child needs to breathe. They’ll likely need mechanical ventilation to treat this, which can lead to atelectasis (lung collapse) and pneumonia.
• Cardiac complications: Cardiomyopathy is a common complication of CMD. It can lead to chronic heart failure.
• Musculoskeletal complications: Your child may develop scoliosis due to immobility. They may also be at an increased risk for osteopenia and bone fractures. Bedsores (pressure ulcers) and joint contractures (tightening of muscles and ligaments around a joint) can develop as well.
• Neurological complications: Your child may be at an increased risk of developing depression and/or anxiety due to living with a chronic condition.

What causes congenital muscular dystrophy?

Mutations (changes) in the genes that are responsible for healthy muscle structure and function cause congenital muscular dystrophy. The mutations mean that the cells that would normally maintain your baby’s muscles can no longer fulfill this role, leading to progressive muscle weakness over time.

There are several genes — and possible genetic mutations — that play a role in muscle function. This is why there are so many different forms of muscular dystrophy, as well as CMD.

The majority of CMDs result from an autosomal recessive inheritance pattern. This means that your child inherited a genetic mutation that causes the condition from both of their biological parents.

Some cases of CMD develop spontaneously, meaning the mutation happened randomly and wasn’t inherited. This is called a de novo mutation.

How is congenital muscular dystrophy diagnosed?

If your baby has symptoms of congenital muscular dystrophy (poor muscle tone being the main sign), their healthcare provider will likely perform a physical exam, neurological exam and muscle exam. Your baby may need to see a pediatric neurologist for more advanced exams.

If they suspect your child has congenital muscular dystrophy, they may recommend any of the following diagnostic tests:

• Creatine kinase blood test: Damage to muscles causes them to release creatine kinase, so elevated levels may indicate muscular dystrophy.
• Electromyography (EMG): This test measures the electrical activity of your child’s muscles and nerves.
• Genetic tests: Certain genetic tests can identify gene mutations that are linked to muscular dystrophy. Comprehensive gene panels can confirm the specific type of CMD in about 60% of cases.
• Muscle biopsy: Your provider may take a small sample of your baby’s muscle tissue. A specialist will then look at the sample under a microscope for signs of muscular dystrophy.
• Echocardiogram and electrocardiogram (EKG): These tests can check to see if CGM is affecting your child’s heart muscles.
• Brain MRI: If possible, your child’s provider may recommend a brain MRI (imaging test). Many types of CMD are linked to specific abnormalities in different areas of the brain.

This may seem like a lot of tests. And it can be emotionally difficult to watch your baby go through them. But know that your baby’s provider wants to make sure they have an accurate diagnosis so they can provide the best care. Symptoms of CMD in infants can look like the symptoms of other conditions, like certain myopathies (muscle disorders) or other metabolic conditions, like glycogen storage diseases and mitochondrial diseases. So, it’s important to find the correct diagnosis.

How is congenital muscular dystrophy treated?

There’s currently no cure for congenital muscular dystrophy, though researchers are actively looking for one.

The main goal of treatment is to manage symptoms and improve your child’s quality of life. Treatments can vary depending on the type of congenital muscular dystrophy and may include:

• Physical and occupational therapies: The main goal of these therapies is to strengthen and stretch your child’s muscles. They can help them maintain movement function.
• Corticosteroids: Corticosteroids, such as prednisolone and deflazacort, may be beneficial for delaying muscle weakness, improving lung function, delaying scoliosis, slowing the progression of cardiomyopathy and prolonging survival.
• Mobility aids: Devices such as canes, braces, walkers and wheelchairs can improve your child’s mobility and help prevent falls.
• Surgery: Your child may need surgery to relieve tension on contracted muscles and to correct spine curvature (scoliosis).
• Heart care: Early treatment with ACE inhibitors and/or beta-blockers may slow the progression of cardiomyopathy and prevent the onset of heart failure. Pacemakers can also help treat heart rhythm problems and heart failure.
• Speech therapy: This can help children who have difficulty with speech and/or swallowing.
• Respiratory care: Cough-assist devices and respirators can help with breathing. Tracheostomy and assisted ventilation may be necessary in cases of respiratory failure.

Your child may also be able to participate in a clinical trial for CMD. Talk with your child’s healthcare team to see if this is an option.

Healthcare providers that treat congenital muscular dystrophy

Your child will likely have a team of healthcare providers to manage CMD. Experts may include:

• Pediatricians.
• Pediatric neurologists.
• Pediatric physiatrists.
• Geneticists.
• Pediatric orthopaedists.
• Pediatric physical therapists.
• Pediatric occupational therapists.
• Pediatric speech-language pathologists.
• Pediatric cardiologists.
• Pediatric pulmonologists.
• Child psychologists.
• Social workers.

Can congenital muscular dystrophy be prevented?

As congenital muscular dystrophy is a genetic condition, there’s nothing you can do at the present time to prevent it.

If you’re concerned about the risk of passing on muscular dystrophy or other genetic conditions before trying to have a biological child, talk to your healthcare provider about genetic counseling. In some situations, prenatal testing may be able to diagnose the condition in early pregnancy.

What is the prognosis for a baby with congenital muscular dystrophy?

It’s difficult for researchers and healthcare providers to predict the prognosis (outlook) of congenital muscular dystrophies with certainty. Your child’s healthcare team will provide as much insight as possible about what to expect while your child is in their care.

In general, congenital muscular dystrophies tend to be more severe and progress more quickly than muscular dystrophies that begin in late childhood or adulthood.

What is the life expectancy of a baby with congenital muscular dystrophy?

The life expectancy of children with congenital muscular dystrophy depends on how quickly the condition progresses (worsens) and which muscles are affected. The most common causes of death in these conditions are respiratory or cardiac complications due to muscle weakness.

How can I help my child with congenital muscular dystrophy?

If your child has congenital muscular dystrophy, it’s important to advocate for them to ensure they get the best medical care and as much access to therapy as possible. Advocating for care can help them have the best possible quality of life.

You and your family may also want to consider joining a support group to meet others who can relate to your experiences.

When should my child see a healthcare provider if they have congenital muscular dystrophy?

If your child has CMD, they’ll need to see their team of healthcare providers regularly to receive treatment and monitor their symptoms.

What questions should I ask my child’s healthcare provider?

It may be beneficial to ask the following questions if your child has received a CMD diagnosis:

• What type of CMD does my child have?
• What treatment do you recommend?
• What’s the complete list of healthcare specialists my child should see?
• Will you be in contact with the other specialists?
• What can I do at home to help improve my child’s quality of life?
• Is there any new research on CMD?
• Are there any new clinical trials for CMD my child may qualify for?
• Can you recommend a support group?