Makindo Medical Notes

Muscular dystrophies are a group of inherited disorders characterised by progressive muscle weakness and wasting. They differ in onset, genetic cause, severity, and prognosis. Early diagnosis is vital for supportive management and family counselling.

🧒 Duchenne Muscular Dystrophy (DMD)

• Onset: Early childhood (2–5 years)
• Features: Progressive weakness, difficulty walking, Gowers’ sign, scoliosis, cardiomyopathy.
• Genetics: Mutation in the DMD gene → complete loss of dystrophin (X-linked recessive).
• Management: Physical therapy, corticosteroids (prednisone), cardiac monitoring, gene therapy in development.
• Prognosis: Progressive disability; life expectancy improving with care (30s–40s).

👦 Becker Muscular Dystrophy (BMD)

• Onset: Adolescence or early adulthood.
• Features: Similar to DMD but milder; proximal weakness.
• Genetics: Mutation in DMD gene → partially functional dystrophin.
• Management: Physiotherapy, corticosteroids, cardiac support.
• Prognosis: Slower progression than DMD, near-normal lifespan possible.

👨 Myotonic Dystrophy

• Onset: Early adulthood (20s–30s).
• Features: Myotonia (delayed relaxation), muscle stiffness, cataracts, arrhythmias.
• Genetics: Expansion of repeats in DMPK (type 1) or CNBP (type 2). Autosomal dominant.
• Management: Symptomatic (myotonia treatment, pacemakers if cardiac involvement), physio.
• Prognosis: Variable; type 1 more severe, type 2 milder.

💪 Limb-Girdle Muscular Dystrophy (LGMD)

• Onset: Childhood to early adulthood.
• Features: Weakness of hip and shoulder girdle muscles → difficulty climbing stairs, lifting objects.
• Genetics: Many subtypes (e.g., CAPN3, DYSF), inheritance autosomal recessive or dominant.
• Management: Physio, OT, supportive care.
• Prognosis: Variable; some slowly progressive with good outcomes, others more disabling.

🙂 Facioscapulohumeral Muscular Dystrophy (FSHD)

• Onset: Adolescence or early adulthood.
• Features: Weakness in face, shoulders, upper arms; winged scapula.
• Genetics: Deletion in regulatory region of DUX4 on chromosome 4 (autosomal dominant).
• Management: Physio, OT, supportive aids.
• Prognosis: Slow progression; many remain independent.

👶 Congenital Muscular Dystrophy (CMD)

• Onset: Birth or early infancy.
• Features: Severe weakness from birth, contractures, delayed motor milestones.
• Genetics: Multiple genes (e.g., LAMA2, COL6A1), often autosomal recessive.
• Management: Physio, orthopaedic interventions, multidisciplinary supportive care.
• Prognosis: Very variable – some achieve walking, others have severe disability.

💡 Teaching Pearl

A key difference between Duchenne and Becker is the degree of dystrophin dysfunction: absent in DMD (severe) vs. partially functional in BMD (milder). Always consider cardiac involvement across muscular dystrophies — it’s a major determinant of long-term outcomes.