Muscular dystrophy is a broad group of genetic neuromuscular disorders affecting the skeletal muscles, causing them to progressively weaken and deteriorate (break down) over time. Muscles rely on multiple proteins to maintain their structural integrity and function, keeping them strong, protecting them from injury, and ensuring they work properly. This condition arises from defects in specific genes responsible for producing muscle proteins, such as dystrophin. When these genes are mutated, the body is unable to produce sufficient or functional levels of these proteins, leading to fragile muscle fibers that are more prone to damage. Over time, this muscle damage impairs normal growth, movement, and function, significantly affecting a child’s mobility and quality of life. While muscular dystrophy is a genetic disorder, meaning that it is often inherited, spontaneous mutations can also occur. Understanding these underlying causes is key to developing effective treatments and managing the condition.
Types of Muscular Dystrophy
Muscular dystrophy is not a single condition but a group of genetic neuromuscular disorders, each with distinct characteristics, severity, and progression. These conditions share a common feature: progressive weakening of the muscles due to defects in muscle proteins. However, the specific symptoms, age of onset, and areas of the body affected can vary greatly depending on the type of muscular dystrophy.
Understanding the type of muscular dystrophy your child has is critical for developing an effective treatment plan. At Children’s Hospital Los Angeles, we specialize in diagnosing and managing muscular dystrophy, tailoring our approach to meet the unique needs of each child and family. From the earliest signs to long-term management, our multidisciplinary team is committed to helping your child live their best possible life.
Here are the most common types of muscular dystrophy we treat:
- Duchenne Muscular Dystrophy (DMD): The most common form, DMD predominantly affects boys and typically appears between ages 2 and 5. Caused by a complete absence of the dystrophin protein, this condition is the most severe form and leads to rapid and severe muscle weakness, often progressing to involve the heart and respiratory systems.
- Becker Muscular Dystrophy (BMD): Sharing a genetic cause with DMD, Becker muscular dystrophy is a milder form. Symptoms often begin in adolescence or later and progress more slowly because some functional dystrophin is present.
- Congenital Muscular Dystrophy (CMD): A group of muscular dystrophies found at birth or in infancy, CMD encompasses several subtypes with varying symptoms. These may cause muscle weakness, joint deformities, and, in some cases, effects on the heart and brain.
Causes and Risk Factors of Muscular Dystrophy
Muscular dystrophy is caused by genetic mutations that disrupt the production or function of proteins vital for muscle health, such as dystrophin. These mutations lead to progressive muscle weakness and damage. While the underlying cause of muscular dystrophy lies in genetic mutations, several factors can increase the likelihood of developing the condition or passing it on to future generations:
- Family History: A strong family history of muscular dystrophy is one of the most significant risk factors. If a parent carries the mutated gene, there is a higher chance of passing it to their children. In some cases, individuals may be carriers without displaying symptoms, but they can still pass the gene mutation to their offspring.
- Gender: Duchenne and Becker muscular dystrophies, which are caused by mutations in the dystrophin gene located on the X chromosome, predominantly affect boys. This is because males have only one X chromosome, and a mutation on this chromosome results in the condition. Females, who have two X chromosomes, are typically carriers and may have milder or no symptoms, as their second X chromosome compensates for the defective gene.
- Critical Periods: Symptoms of muscular dystrophy often emerge during specific developmental windows, particularly between the ages of 2 and 5 for Duchenne muscular dystrophy. This period is crucial for identifying early signs, such as difficulty with mobility, frequent falls, or delays in reaching physical milestones. Early detection can significantly impact the management and progression of the condition.
In some cases, spontaneous gene mutations can occur, meaning there is no prior family history of muscular dystrophy. These mutations can arise during reproduction or early fetal development and result in the same disruptions to muscle proteins as inherited mutations.
Signs and Symptoms of Muscular Dystrophy
Muscular dystrophy presents with a range of symptoms that vary depending on the specific type and severity of the condition. These signs often emerge in early childhood and progressively worsen over time, impacting mobility, balance, and overall quality of life. Recognizing these symptoms early is crucial for prompt diagnosis and intervention, which can help slow the progression and improve outcomes.
Common signs to watch for:
- Progressive Muscle Weakness: One of the most common symptoms, muscle weakness, usually begins in the legs and pelvis, making activities like standing, walking, or climbing stairs increasingly difficult.
- Mobility Challenges: Frequent falls, difficulty rising from a sitting or lying position, and trouble running or jumping are often among the first noticeable signs.
- Enlarged Calf Muscles (Pseudohypertrophy): As damaged muscle tissue is replaced with fat and connective tissue, the calves may appear unusually large, even as overall muscle strength diminishes.
- Abnormal Gait: Children may exhibit toe-walking, a waddling gait, or both, as they compensate for weakened muscles.
- Delayed Motor Milestones: In some cases, children with muscular dystrophy may experience delayed walking, running, or other motor skills compared to their peers.
Complications of Muscular Dystrophy
As muscular dystrophy progresses, its effects can extend beyond the muscles, impacting multiple body systems and leading to significant health challenges. Early recognition and proactive management of these complications are essential to improving a child’s quality of life and long-term outcomes.
Key Complications
- Respiratory Challenges: Weakness in the respiratory muscles can make it difficult for children to breathe deeply, cough effectively, or clear their airways. Over time, this can increase the risk of respiratory infections and lead to chronic breathing difficulties or respiratory failure, requiring interventions, such as support from a ventilator.
- Cardiac Concerns: Muscular dystrophy can affect the heart muscle, leading to conditions, such as cardiomyopathy, where the heart becomes weakened or enlarged. This can result in reduced heart function, irregular heart rhythms, and, in severe cases, heart failure. Routine cardiac monitoring and early interventions, including medications or devices, are critical for managing these risks.
- Skeletal Changes: Progressive muscle weakness can lead to difficulty maintaining balance and skeletal deformities, including scoliosis (curved spine). These changes may cause discomfort, restrict lung capacity, and impair mobility, often leading to the child needing orthopedic interventions or braces.
- Contractures and Joint Stiffness: Muscle shortening and joint stiffness, known as contractures, can reduce flexibility and limit movement. Regular physical therapy and stretching exercises can help manage this complication.
- Nutritional and Swallowing Difficulties: In advanced stages, weakened muscles may affect chewing and swallowing, increasing the risk of malnutrition or aspiration (foods or liquids being inhaled into the lungs instead of the stomach). Nutritional support and swallow therapy may be necessary to address these challenges.
- Fatigue and Reduced Endurance: As muscles weaken, children with muscular dystrophy may experience significant fatigue, impacting their ability to participate in daily activities or maintain independence.
Diagnoses and Tests for Muscular Dystrophy
Diagnosing muscular dystrophy requires a comprehensive and precise approach to identify the specific type of the disorder and assess its progression. At CHLA, we employ advanced diagnostic tools and techniques to provide clarity and guide treatment decisions. Early and accurate diagnosis is vital in managing the disease and improving outcomes for children.
Key Diagnostic Methods
- Medical History: Understanding your child’s medical and family history is a crucial first step. This helps identify potential genetic patterns and determines the likelihood of inherited forms of muscular dystrophy. A thorough history review also provides insight into related conditions or symptoms within the family that may inform the diagnostic process.
- Physical Exam: A thorough physical examination evaluates muscle strength, coordination, and reflexes, providing an immediate understanding of the condition’s impact on your child’s mobility and overall function.
- Blood Tests: A blood test to measure creatine kinase (CK) levels is often one of the initial diagnostic steps. Elevated CK levels indicate muscle damage and help confirm the need for further testing. These tests also provide a baseline for monitoring disease progression and response to treatment.
- Genetic Tests: Genetic testing is essential for pinpointing mutations in specific genes, such as the dystrophin gene in Duchenne and Becker muscular dystrophies. This advanced test not only confirms the diagnosis but also identifies the exact genetic mutation, enabling tailored treatment plans and genetic counseling for families.
- Muscle Biopsy: A muscle biopsy involves extracting a small sample of muscle tissue for microscopic analysis. This test provides detailed insights into the condition of the muscle fibers, helping to differentiate between various types of muscular dystrophy and other neuromuscular disorders.
Our multidisciplinary approach ensures that every aspect of your child’s condition is evaluated with precision and care. The diagnostic process at CHLA not only identifies the type and severity of muscular dystrophy but also lays the foundation for creating a personalized and effective care plan. Learn more about our Neuromuscular Disorders Center.
Treatment for Muscular Dystrophy
Although there is no cure for muscular dystrophy, advancements in treatment options allow children with the condition to lead healthier and more fulfilling lives. At CHLA, we focus on improving quality of life, slowing disease progression, and addressing specific symptoms through personalized care plans.
Key Treatment Options
- Medications: Corticosteroids, such as prednisone and deflazacort, are commonly prescribed to delay muscle damage and preserve strength for as long as possible. For children with Duchenne muscular dystrophy (DMD), medications like ACE inhibitors and beta-blockers are used to manage cardiomyopathy, a condition that weakens the heart muscle. These medications can slow the progression of heart complications and enhance overall cardiac health.
- Physical Therapy: Physical therapy plays a critical role in maintaining muscle strength, flexibility, and mobility. Regular stretching and strengthening exercises help prevent contractures (joint stiffness) and improve range of motion. Occupational therapy may also be incorporated to help children adapt to daily activities and maintain independence as their condition progresses.
- Mobility Aids: As muscular weakness progresses, mobility aids, such as braces, walkers, and wheelchairs, become essential for maintaining safety and independence. These tools are tailored to each child’s specific needs, allowing them to remain active and engaged in their daily routines while reducing the risk of falls and injuries.
- Gene Therapy Advances: CHLA is at the forefront of cutting-edge research, offering innovative treatments like gene therapy for Duchenne muscular dystrophy. For example, Elevidys® gene therapy aims to replace the defective dystrophin gene in children with Duchenne muscular dystrophy, potentially reducing symptoms and improving muscle function.
- Supportive Therapies: Comprehensive care includes respiratory therapy to improve breathing, nutritional counseling to maintain a healthy weight and prevent aspiration, and psychological support for children and their families. These supportive therapies ensure that every aspect of the child’s well-being is addressed.
Gene Therapy for Duchenne Muscular Dystrophy
Elevidys is an innovative, one-time gene transfer therapy developed specifically for boys with Duchenne muscular dystrophy. By attempting to address the root cause of DMD, Elevidys introduces a functional micro-dystrophin gene to help slow the progression of the disease. Approved by the FDA in 2023, with label expansion in 2024, this treatment is available at CHLA for boys aged 4 and older who are ambulatory. CHLA is among the highest-volume institutions in the United States treating children with Elevidys. Discover more about how CHLA is leading the way in cell and gene therapy.
Muscular Dystrophy Care at Children's Hospital Los Angeles
Families choose CHLA for muscular dystrophy care because we’re committed to providing the most advanced, compassionate, and family-centered treatment available. As one of the first centers in the nation to offer Elevidys gene therapy commercially for Duchenne muscular dystrophy, CHLA treats one of the largest numbers of children in the U.S. using Elevidys. Our Neuromuscular Disorders Clinic offers a multidisciplinary approach, bringing together experts who specialize in neuromuscular disorders to support your child and family at every step. Learn more about the muscular dystrophy treatment options we offer at our Neuromuscular Disorders Clinic.
FAQs
What are usually the first signs of muscular dystrophy?
Early signs include decreased muscle strength, frequent falls, and difficulty running or climbing stairs. Loss of muscle mass, mild symptoms, and leg pain may also be present, signaling early muscle weakness.
What is the age of onset for muscular dystrophy?
The age of onset varies by type. Duchenne symptoms often appear between ages 2 and 4, while Becker usually starts in adolescence. Limb-girdle muscular dystrophy may develop later, in the teen years or adulthood.
What can trigger muscular dystrophy?
Muscular dystrophy is a genetic disease, primarily caused by inherited mutations. A family history significantly increases risk, though spontaneous mutations can occur without prior family involvement.