Becker Muscular Dystrophy (BMD): A Comprehensive Overview

By SWA

Becker muscular dystrophy (BMD) is a genetic neuromuscular disorder that causes progressive muscle weakness, primarily affecting skeletal and cardiac muscles. It is less severe and progresses more slowly than Duchenne muscular dystrophy (DMD). Both disorders are caused by mutations in the same gene, known as the DMD gene, which encodes the muscle protein dystrophin.

DMD – dystrophin Homo sapiens (human)

  • Also known as: BMD, CMD3B, DXS142, DXS164, DXS206, DXS230, DXS239, DXS268, DXS269, DXS270, DXS272, MRX85

Cause of Becker Muscular Dystrophy

➤ Gene Involved

  • DMD gene, located on the X chromosome (Xp21.2)

  • Largest known human gene (~2.2 million base pairs)

  • Encodes dystrophin, a critical structural protein that anchors the cytoskeleton of muscle cells to the extracellular matrix

➤ Protein Affected: Dystrophin

Dystrophin stabilizes muscle fiber membranes during contraction. Without enough functional dystrophin, muscle fibers are damaged over time and gradually replaced by fat and scar tissue.

➤ Type of Mutation

  • In BMD:

    • In-frame deletions or mutations

    • Produce partially functional dystrophin

  • In DMD:

    • Out-of-frame mutations

    • Lead to nonfunctional or absent dystrophin

ConditionType of MutationDystrophin ProducedSeverity
BMDIn-frameReduced but functionalMild to moderate
DMDOut-of-frameNone or nonfunctionalSevere        

Inheritance Pattern

  • X-linked recessive

  • Males (XY) are typically affected

  • Females (XX) are carriers — usually asymptomatic, though some may experience:

    • Mild muscle cramps or weakness

    • Cardiomyopathy (in rare cases)

Each son of a carrier mother has a 50% chance of being affected, and each daughter has a 50% chance of being a carrier.

Symptoms of BMD

➤ Typical Onset

Symptoms usually appear between ages 5 and 25, but can vary widely.

➤ Muscle-Related Symptoms

  • Progressive weakness in pelvic, thigh, and shoulder muscles

  • Calf muscle enlargement (pseudohypertrophy)

  • Difficulty:

    • Running or walking long distances

    • Climbing stairs

    • Rising from the floor (positive Gowers’ sign)

  • Muscle cramps, fatigue, and frequent falls

➤ Other Complications

SystemPossible Issues
Cardiac        Dilated cardiomyopathy, arrhythmias
Respiratory        Breathing difficulties (late stages)
Skeletal        Scoliosis, joint contractures
General        Fatigue, poor stamina

 

Disease Progression

➤ Typical Stages of Progression

Age RangeSigns & Symptoms
Childhood        Often mild; some may have normal development
Teens–20s        Muscle weakness becomes more evident
30s–40s        Increased mobility challenges; assistive aids
40s+        Risk of cardiomyopathy, potential wheelchair use 

Diagnosis of BMD

➤ 1. Blood Tests

  • Creatine Kinase (CK): Elevated (up to 10–100x normal), indicating muscle damage

➤ 2. Genetic Testing (First-line)

  • Detects mutations in the DMD gene

  • Performed via blood or saliva

  • Methods:

    • MLPA (Multiplex Ligation-dependent Probe Amplification): Detects deletions/duplications

    • NGS (Next-Generation Sequencing): Identifies point mutations and small indels

➤ 3. Muscle Biopsy (If Genetic Test Is Inconclusive)

  • Analyzes dystrophin in muscle fibers

  • Tests:

    • Immunohistochemistry (IHC): Visualizes dystrophin presence

    • Western blot: Measures quantity and size of dystrophin

Result TypeSuggests
No dystrophin            Duchenne muscular dystrophy
Reduced dystrophin            Becker muscular dystrophy
Normal dystrophin            Rules out DMD/BMD

➤ 4. Cardiac Evaluation

  • Echocardiogram and ECG to monitor for cardiomyopathy or rhythm issues

Treatment of Becker MD

There is no cure, but treatment focuses on managing symptoms, improving quality of life, and slowing disease progression.

Treatment AreaExamples
Physical therapy    To maintain mobility and prevent contractures
Medications    Corticosteroids (e.g., prednisone, deflazacort)
Cardiac care    ACE inhibitors, beta blockers, routine monitoring
Respiratory support        Non-invasive ventilation (e.g., BiPAP) if needed
Orthopedic support    Braces, stretching, scoliosis management
Psychosocial support    Counseling, education support, quality of life programs
Genetic counseling    For families and at-risk female carriers

What to Avoid

To help preserve muscle function and delay progression, patients should avoid:

Risk FactorWhy to Avoid
Eccentric overuse    Causes more muscle damage (e.g., downhill running, heavy lifting)
Prolonged immobility    Leads to stiffness, contractures, weakness
High-impact sports    Risk of muscle injury
Obesity    Adds extra strain on weakened muscles
Smoking    Worsens respiratory and cardiovascular health
Untreated heart issues    May lead to heart failure or sudden death

Recommended:

  • Low-impact activities: Swimming, biking

  • Regular checkups: Neurology, cardiology, pulmonology

  • Assistive devices: As needed for mobility

     

DMD Gene SNPs (rsIDs) and Mutation Insight

While Becker and Duchenne MD are often caused by large deletions/duplications, the DMD gene also contains many single nucleotide polymorphisms (SNPs) with rsIDs.

➤ Examples of SNPs in DMD gene (Xp21.2)

rsIDLocationType
rs1800273    X:32,420,290    Synonymous
rs1800271    X:32,412,917    Missense
rs5900785    X:31,594,183    Intronic  

TAB3 Non Coding Transcript Variant
TAB3-AS1 rs1905204 Intron Variant

Note: Most pathogenic mutations in BMD/DMD do not have rsIDs because they are not single-nucleotide changes, but rather large-scale deletions, duplications, or frame-shift mutations.

Summary Table

FeatureBecker Muscular Dystrophy (BMD)
Gene        DMD (X chromosome, Xp21.2)
Protein        Partially functional dystrophin
Onset        After age 5 (varies)
Inheritance        X-linked recessive
Symptoms        Muscle weakness, calf hypertrophy, cramps
Complications        Cardiomyopathy, respiratory issues
Progression        Slow; many remain ambulatory into adulthood
Diagnosis        CK test, genetic testing, muscle biopsy
Treatment        Symptom management, cardiac care, therapy
Life Expectancy        Often normal with good cardiac care

Summary Table: Mineral Status in DMD/BMD

MineralIssueImpact
Calcium    Intracellular overload    Muscle damage, cell death
Phosphorus    Low (from steroids)    Weak muscles, bone issues
Magnesium    Often low    Cramps, fatigue, arrhythmias
Potassium    Low or high    Weakness, heart rhythm problems
Sodium    Fluctuates with stress/steroids    Fatigue, dehydration
Zinc/Selenium    Often low    Oxidative stress, poor immune response
Vitamin D    Often low    Bone loss, fractures

The psychological impact of Becker muscular dystrophy (BMD) can be deeply challenging, especially when individuals are pushed beyond their physical or emotional limits. While BMD is a physical condition, it profoundly affects mental health, identity, and social connection. The constant effort to meet expectations—either self-imposed or from others—can lead to emotional exhaustion, depression, and anxiety, particularly as independence declines or the future feels uncertain. Feelings of frustration, anger, and grief often emerge when physical abilities diminish, social roles shift, or limitations are misunderstood. Being pushed too hard can result in mental breakdowns, physical setbacks, and a deep sense of isolation or resentment. A compassionate, individualized approach that respects boundaries is essential to support both the emotional and physical well-being of those living with BMD.

Conclusion

Becker muscular dystrophy is a genetically inherited, progressive disorder with variable severity. Though it cannot be cured, early diagnosis, ongoing care, and proactive management — especially of cardiac and respiratory health — can help individuals live long, fulfilling lives.

Though it cannot be cured, early diagnosis, ongoing care, and proactive management — especially of cardiac and respiratory health — can help individuals live long, fulfilling lives. Just as important as physical treatment is the recognition of the emotional and psychological toll the condition can take. When individuals are pushed beyond their limits — physically, emotionally, or socially — it can lead to burnout, depression, anxiety, and a loss of identity. Support systems must be mindful not only of what the body can handle but also of what the mind and spirit need. Respecting personal limits, encouraging adaptive goals, and promoting mental health care are essential parts of truly comprehensive management.

Reference: 

Ion Channels of the Sarcolemma and Intracellular Organelles in Duchenne Muscular Dystrophy: A Role in the Dysregulation of Ion Homeostasis and a Possible Target for Therapy
https://pmc.ncbi.nlm.nih.gov/articles/PMC9917149/

Duchenne and Becker muscular dystrophy: Cellular mechanisms, image analysis, and computational models: A review https://onlinelibrary.wiley.com/doi/full/10.1002/cm.21826

DMD gene https://medlineplus.gov/genetics/gene/dmd/


© 2000-2025 Sieglinde W. Alexander. All writings by Sieglinde W. Alexander have a fife year copy right. Library of Congress Card Number: LCN 00-192742

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