Muscular Dystrophy / Duchenne Muscular Dystrophy
Causes, Types, Symptoms, Diagnosis, and Treatment Options

What is Muscular Dystrophy Disorder?

Muscular dystrophy (MD) is a group of rare, genetic disease that causes progressive muscle weakness, muscle loss, and degeneration. MD is a chronic, noncommunicable disorder that affects skeletal and cardiac muscles. It can manifest at any age but is most often diagnosed during childhood. The progression of the condition varies depending on the type and severity of the disease.

What are the causes of Muscular Dystrophy?

• Muscular dystrophy (MD) is caused by gene mutations that affect the proteins that strengthen and protect muscles. 
• MD is usually inherited from one or both parents, but it can also occur spontaneously
• The gene mutations cause changes in muscle fibers, which leads to muscle weakness and progressive disability

What are the Types of Muscular Dystrophy?

• Duchenne muscular dystrophy (DMD): The most common type of muscular dystrophy in children, which is characterized by rapid progression of muscular dystrophy leading to loss of muscle strength due to which most of the children are unable to walk by the age of 12.
  
• Becker muscular dystrophy (BMD): Less common than DMD, and BMD progresses more slowly and usually affects the male children. Symptoms usually appear between the ages of 5 and 15 years
• Myotonic muscular dystrophy: This is characterized by an inability to relax muscles following contractions. Facial and neck muscles are usually the first to be affected.
• Distal muscular dystrophy: Causes weakness and atrophy of the muscles in the hands, feet, lower legs, and forearms. It is usually a late-onset type of muscular weakness and dystrophy found between the ages of 40 and 60. 
• Emery-Dreifuss muscular dystrophy: In this type of dystrophy, muscle weakness and joint contractures are usually observed in age groups between childhood and early teens. 
• Facioscapulohumeral muscular dystrophy (FSHD): Along with muscle weakness and loss of muscle tissue, the majority of FSHD patients also have high-frequency hearing loss and retinovasculopathy. This type of dystrophy is usually seen in late stages of childhood and early adulthood

What are the Symptoms of Muscular Dystrophy?

• Weakness in the muscles of neck, legs, arms, and other areas. 
• Difficulty in walking, running, jumping, or climbing stairs. 
• Children with DMD may fall more than other children 
• Children with DMD walk on their toes with an arched lower back.(waddling gait)
• Learning and behavioral difficulties are seen in majority of the effected boys
• The diaphragm and other muscles that operate the lungs may weaken, making it difficult to breathe. 
• The heart muscle may weaken, leading to fatigue, shortness of breath, and swelling of the feet. 
• Facial weakness, including an inability to whistle or close eyes, enlarged tongue and forearm muscles, joint contractures, and scoliosis. 

What is Duchenne Muscular Dystrophy (DMD)?

Duchenne muscular dystrophy (DMD) is a rare muscle disorder caused by mutation of  the DMD gene on the X chromosome. The cause of Duchenne Muscular Dystrophy (DMD) is found to be because of  a mutation in the DMD gene on the X chromosome and mostly affects the male fetus in utero. This gene regulates the production of a protein called dystrophin that is found in the inner side of the membrane of skeletal and cardiac muscle cells. Dystrophin is found to play an important role in maintaining the membrane of the muscle cells. Hence, a disruption in the protein called dystrophin effects the muscle cells, leading to atrophic and dystrophic changes within the cells. DMD is a type of muscular disease usually seen in children between three and six years of age. 

What are the Symptoms of  Duchenne Muscular Dystrophy (DMD)?

• Weakness and atrophy of the upper legs, pelvic, upper arms, and shoulder muscles.
• Disproportionately bulky muscles in some areas (pseudohypertrophy).
• Developmental delays with difficulty sitting or standing, toe walking, waddling gait, and  frequent falls.
• Gower’s sign is typically noticed in Children with DMD (difficulty rising from a sitting position.)
• Awkward and abnormal movements in toddlers and young children.
• Curvature of the spine (scoliosis or lordosis)
• Reduced bone density leading to increased risk of fractures (hips, spine)
• Mild to moderate non-progressive intellectual impairment.
• Learning disabilities, attention deficits, or autism spectrum disorders is seen in few children
• Cardio-pulmonary complications effecting the heart and respiratory muscles is seen in late teens

What are the Clinical Features of Duchenne Muscular Dystrophy (DMD)?

Some of the few common clinical features noticed during a clinical examination include:

• Proximal muscle weakness
• Delayed developmental milestones
• Toe walking & Waddling gait
• Enlarged Calf Muscles
• Scoliosis or lordosis
• Attention deficit & Autism spectrum disorders

How to Diagnose Duchenne Muscular Dystrophy (DMD)?

A diagnosis of DMD is made based upon a thorough clinical evaluation, a detailed patient history, and a variety of specialized tests, including molecular genetic tests.

Blood tests may reveal elevated levels of the creatine kinase (CK), an enzyme that is found at abnormally high levels when muscle is damaged. The detection of elevated CK levels can confirm that muscle is damaged or inflamed but cannot confirm a diagnosis of DMD.

Specialized blood tests (e.g., creatine kinase) that evaluate the presence and levels of certain proteins in muscle (immunohistochemistry) are  used.

Molecular genetic tests involve the examination of DNA to identify disease-causing variants in the DMD gene.

Biopsy is indicated if the genetic tests are not informative. This involves surgical removal and microscopic examination (biopsy) of affected muscle tissue to find any histopathological changes within the cells and muscle fibers.

Specialized Muscle Biopsy: In some cases, a specialized test can be performed on muscle biopsy samples that can determine the presence and levels of specific proteins within cells. 

Antibody Testing: Various techniques such as immunostaining, immunofluorescence, or Western blot (immunoblot) can be used. These tests involve the use of certain antibodies that react to certain proteins, such as dystrophin.

What is the Treatment for  Duchenne Muscular Dystrophy (DMD)?

There is no curative treatment available for DMD. However, the treatments are aimed at symptomatic relief, which is specific to the individual condition. For DMD, treatment is always symptomatic and supportive. However, with advanced medical diagnostic technology available, is it now possible to know 

• Corticosteroids are used as a standard of care to treat individuals with DMD. 
• These drugs help in slowing down  the progression of muscle weakness in affected individuals and delay the loss of ambulation by 2-3 years. 
• Physical therapy and exercises help  to build muscle strength and prevent contractures. 
• Surgery may be recommended in some patients to treat contractures or scoliosis. 
• Braces may be used to prevent the development of contractures. 
• Mechanical aids like canes, braces, and wheelchairs may become necessary to aid walking
• Children diagnosed with DMD should be monitored regularly for potential heart involvement.
•  Respiratory complications can sometimes become severe, necessitating the need for a ventilator to assist breathing.
• Genetic counseling is very important, especially in families carrying this DMD gene.

So that  the pregnant women in these families carrying the gene can undergo thorough prenatal testing like Amniocentesis & Chorionic villus sampling (CVS) to detect the DMD gene and make an informed decision.

Frequently Asked Questions About Muscular Dystrophy 

Is muscular dystrophy an autoimmune disease?

Muscular dystrophy (MD) is not an autoimmune disease. It is a group of genetic disorders caused by mutations in specific genes responsible for muscle health and function.

How can muscle weakness be treated?

Muscle weakness and loss of muscle caused by Duchenne Muscular Dystrophy (DMD) are irreversible, and currently, only symptomatic and supportive treatments are available. However, raising awareness about the specific genetic mutations responsible for DMD is crucial. Families with a history of DMD are encouraged to undergo prenatal genetic testing to make informed decisions regarding future generations and reduce the risk of transmission.

What is the cost of DMD treatment?

The treatment for managing DMD is only symptomatic and supportive, completely varies depending on the region and severity of the condition, and the treatment plan is suggested after a thorough examination by an expert along with investigations.

What is the main cause of muscular dystrophy?

Muscular dystrophy is primarily caused by genetic mutations in the genes responsible for producing proteins essential for muscle function. For example, Duchenne muscular dystrophy results from mutations in the DMD gene, which leads to a lack of dystrophin, a protein that helps maintain muscle strength and integrity.

What organs are affected by muscular dystrophy?

Muscular dystrophy primarily affects the skeletal muscles, leading to progressive weakness and wasting. Reduced bone density is seen, which in turn leads to frequent fractures. The cardiac and respiratory muscles are also affected, leading to severe life-threatening complications if not diagnosed early.

Can muscular dystrophy be prevented?

The only way to prevent Duchenne Muscular Dystrophy (DMD) is through genetic testing to determine susceptibility to mutations in the DMD gene. Prenatal testing during early pregnancy can help identify the risk of passing the disorder to future generations. While DMD cannot be cured, early diagnosis and timely intervention can play a significant role in managing symptoms and improving the quality of life for affected individuals.

Disclaimer:

“The content of this publication has been developed by a third party content provider who is clinicians and/or medical writers and/or experts. The information contained herein is for educational purpose only and we request you to please consult a Registered Medical Practitioner or Doctor before deciding the appropriate diagnosis and treatment plan.”