Becker Muscular Dystrophy (BMD) Information Accuracy Assessment
The information presented is largely accurate, with important clarifications needed regarding glucocorticoid use and the timing of symptom onset.
Genetic Basis and Pathophysiology
The description of BMD genetics is correct:
- BMD results from in-frame deletions in the dystrophin gene that produce a partially functional dystrophin protein with retained amino and carboxy termini, allowing the protein to localize to the sarcolemma 1, 2
- This contrasts with DMD, where frameshift mutations result in nearly complete absence of dystrophin 1, 2
- X-linked recessive inheritance pattern is accurate 1
Clinical Presentation
The clinical features listed are accurate:
- BMD presents with a milder and more variable phenotype than DMD 1
- Progressive proximal muscle weakness affecting pelvic, thigh, and shoulder girdles is characteristic 1
- Calf pseudohypertrophy occurs in BMD 3
- Normal cognition is typical in BMD patients 1
- Gower sign and toe walking are appropriate clinical findings 1
Diagnostic Approach
The diagnostic workup is correctly described:
- Elevated creatine kinase (CK) and aldolase are expected findings 3, 4
- Genetic testing demonstrating in-frame deletions is the definitive diagnostic method 1
- Muscle biopsy showing reduced but present dystrophin is accurate 2
Management - Critical Correction Needed
The recommendation for prednisone in BMD requires significant clarification:
- Glucocorticoids (prednisone) are NOT typically used in BMD patients 1
- Glucocorticoid therapy is standard for DMD, where randomized trials showed prolonged ambulation by 3 years 1
- BMD patients are not typically treated with glucocorticoids due to their milder phenotype and maintained ambulation 1
ACE inhibitors for cardiomyopathy management is appropriate:
- Standard heart failure therapies including ACE inhibitors should be initiated when cardiac dysfunction is detected 4
- Beta-blockers and diuretics may also be indicated 4
Complications
The statement about dilated cardiomyopathy is accurate:
- Dilated cardiomyopathy is the most common cardiac involvement in BMD 1
- Cardiomyopathy has become a leading cause of death in dystrophinopathies with improved respiratory care 1
- Chamber dilation occurs only in late stages; early disease presents with dysfunction without dilation 1
- Cardiac involvement is variable in age of onset and severity 1
Key Pitfall to Avoid
Do not prescribe glucocorticoids for BMD as you would for DMD - this is the most critical error in the presented information 1. The milder phenotype and different natural history of BMD do not warrant routine glucocorticoid therapy that has proven benefit in DMD.