G71.01 Duchenne or Becker muscular dystrophy

Name of the Condition

• Duchenne or Becker muscular dystrophy

Summary

Duchenne or Becker muscular dystrophy is a genetic disorder characterized by progressive muscle weakness and degeneration. These conditions result from defects in the dystrophin protein, leading to impaired muscle function over time. Severity and progression vary, with Duchenne typically presenting in early childhood and progressing more rapidly than Becker.

Causes

Duchenne or Becker muscular dystrophy is caused by mutations in the DMD gene, which disrupts the production or function of dystrophin, a protein essential for muscle fiber stability. These mutations are inherited in an X-linked recessive pattern, meaning the condition primarily affects males, while females are usually carriers.

Risk Factors

• Family history of Duchenne or Becker muscular dystrophy.
• Male gender (due to X-linked inheritance).
• Carrier status in female relatives.

Symptoms

• Progressive muscle weakness, starting in the legs and pelvis.
• Difficulty walking, running, or climbing stairs.
• Muscle wasting (atrophy) and pseudohypertrophy (enlarged calf muscles).
• Delayed motor milestones in children.
• Respiratory or cardiac complications in advanced stages.

Diagnosis

Diagnosis involves clinical evaluation, muscle strength testing, and specialized tests such as electromyography (EMG) to assess muscle electrical activity. Blood tests for elevated creatine kinase (CK) levels and genetic testing to identify DMD gene mutations are commonly used. Muscle biopsy may confirm dystrophin deficiency.

Treatment Options

Treatment focuses on managing symptoms and slowing progression. Options include corticosteroids to preserve muscle function, physical therapy to maintain mobility, respiratory support for breathing difficulties, and cardiac monitoring for heart complications. Emerging therapies like exon-skipping drugs may be considered in specific cases.

Prognosis and Follow-Up

Prognosis varies by subtype: Duchenne often leads to loss of ambulation by adolescence and reduced life expectancy, while Becker has a milder course with longer survival. Regular follow-up with neurologists, cardiologists, and pulmonologists is essential to monitor muscle, heart, and respiratory function.

Complications

• Progressive loss of mobility and independence.
• Respiratory failure due to weakened respiratory muscles.
• Cardiomyopathy and heart failure.
• Scoliosis from muscle imbalance.
• Contractures and joint stiffness.

Lifestyle & Prevention

• Engage in regular physical therapy to maintain muscle strength.
• Use assistive devices (e.g., braces, wheelchairs) as needed.
• Monitor and manage respiratory and cardiac health.
• Genetic counseling for families to understand inheritance risks.

When to Seek Professional Help

Seek immediate medical attention for sudden worsening of muscle weakness, difficulty breathing, chest pain, or signs of heart failure. Regular check-ups are recommended to address complications early.

Tips for Medical Coders

Document the specific subtype (Duchenne or Becker) when clinically confirmed, as this may impact coding specificity. Ensure documentation supports the diagnosis, including genetic testing results or clinical findings consistent with dystrophin-related muscular dystrophy. Code G71.01 is appropriate for confirmed cases of Duchenne or Becker muscular dystrophy.