Muscular Dystrophy

Overview

Muscular Dystrophy (MD) refers to a group of inherited genetic disorders that cause progressive weakness and loss of muscle mass. Over time, the muscles degenerate and weaken due to abnormalities in muscle proteins, especially one called dystrophin, which is essential for muscle function.
There are over 30 different types of muscular dystrophy, each varying by age of onset, rate of progression, muscles affected, and severity.

Types of Muscular Dystrophy

Each type varies in severity, onset, and muscles affected :

Duchenne Muscular Dystrophy (DMD) - most common in children, especially boys.
Becker Muscular Dystrophy (BMD) - similar to DMD but slower progression.
Myotonic Dystrophy - affects adults; causes prolonged muscle contractions.
Facioscapulohumeral MD (FSHD) - affects face, shoulders, upper arms.
Limb-Girdle MD - affects hips and shoulders.
Emery-Dreifuss MD - affects upper arms, lower legs, and heart.
Congenital MD - present at birth.

Goals of Therapy

Therapy for MD focuses on :

Preserving muscle strength and function.
Preventing or delaying complications.
Improving mobility and independence.
Enhancing overall quality of life

Causes of Muscular Dystrophy

Muscular dystrophies are genetic disorders, usually caused by mutations in genes responsible for muscle structure and function.

Most forms are inherited from one or both parents.
Some cases result from spontaneous genetic mutations (de novo) with no family history.
The most commonly affected gene in MD is the DMD gene, which encodes the dystrophin protein.

Inheritance Patterns :

X-linked recessive : (e.g., Duchenne & Becker MD) – mainly affects males.
Autosomal dominant : (e.g., Myotonic MD, FSHD) – affects both sexes.
Autosomal recessive : (e.g., Limb-Girdle MD).

Symptoms of Muscular Dystrophy

Symptoms vary widely based on type, but may include :

Progressive muscle weakness.
Muscle wasting (loss of muscle mass).
Difficulty walking or frequent falls.
Gait abnormalities (e.g., waddling).
Trouble standing up or climbing stairs.
Contractures (shortening of muscles or tendons).
Spinal curvature (scoliosis).
Respiratory problems.
Cardiomyopathy (heart muscle weakness).
Swallowing or speech issues.
Facial muscle weakness (in some types).

Diagnosis of Muscular Dystrophy

Diagnosis typically involves a combination of :

Medical History & Physical Examination

Family history of MD.
Signs of muscle weakness, posture, reflexes

Genetic Testing

Identifies specific gene mutations (e.g., DMD gene).
Confirms the type of MD

Muscle Biopsy

Microscopic examination of muscle tissue.
Detects muscle fiber abnormalities and lack of dystrophin.

Blood Tests

Elevated creatine kinase (CK) – a marker of muscle damage.

Electromyography (EMG) & Nerve Conduction Studies

Measures muscle response to nerve stimulation.

Heart & Lung Tests

ECG, echocardiogram.
Pulmonary function tests.

Prognosis

Prognosis depends on type of MD, severity, and treatment access.
Some forms (like Duchenne MD) significantly reduce life expectancy (20s–30s).
Others (like Myotonic MD or FSHD) may allow near-normal life spans with management.
Early diagnosis and comprehensive care greatly improve outcomes.