Muscular Dystrophy

Muscular Dystrophy (MD) is a group of inherited disorders that weaken the musculoskeletal system and hinder locomotion. These disorders are characterized by defects in muscle proteins. The result is progressive skeletal muscle weakness and loss of muscle tissue, with symptoms worsening over time.

What is Muscular Dystrophy (MD)?

Muscular Dystrophy, or MD, is a group of more than 30 diseases characterised by progressive degeneration of the skeletal muscles that control movement. The disorders differ in terms of distribution, extent of muscle weakness, age of onset, rate of progression, and pattern of inheritance.

Causes of Muscular Dystrophy

Muscular dystrophies are genetic disorders caused by mutations in genes essential for muscle structure and function. These mutations lead to defective or absent proteins, causing progressive muscle weakness and degeneration.

Duchenne and Becker MD result from mutations in the dystrophin gene.
Myotonic dystrophy involves the DMPK or CNBP genes.
Limb-girdle, congenital, oculopharyngeal, and other types are linked to mutations in various muscle-related genes.

Inheritance patterns vary, as being X-linked recessive, autosomal dominant, or autosomal recessive, depending on the type. Most cases are inherited, but rare spontaneous mutations can occur in individuals with no family history.

Common Symptoms of Muscular Dystrophy

The characteristics associated with this group of diseases include:

Muscles may be affected locally (shoulder, pelvis, limbs) or throughout the body. Severe forms tend to occur in childhood and adolescence.
Delayed development of muscle motor skills
Difficulty using one or multiple groups of muscles
Loss of strength in a muscle/ muscle group (in adults)
Loss in muscle size
Delayed walking and waddling gait
Frequent falls due to poor balance
Ptosis or drooping of the eyelid
Mental retardation

Common symptoms of Muscular Dystrophy

Medical Signs and Tests for Muscular Dystrophy

Considering medical history and family history, a doctor might run a few exams and tests to confirm the diagnosis.

A doctor’s examination might reveal:

Scoliosis (Abnormally curved spine)
Joint contractures (clubfoot/ clawhand, etc.)
Hypotonia (Low Muscle Tone)
Arrhythmia
Pseudohypertrophy of muscle, where a buildup of fat and connective tissue makes the wasted muscle appear larger

Tests conducted to diagnose the presence of Muscular Dystrophy include:

ECG (Electrocardiogram)
EMG (Electromyography)
Blood tests, including CPK (Creatine phosphokinase)level; elevated CPK indicates muscular dystrophy
Genetic Testing

T[a]ypes of Muscular Dystrophy

Type of MD	Symptoms	Age of onset
Duchenne	Muscle weakness Trouble walking, running, jumping, and standing up Breathing difficulties Heart weakness Scoliosis Learning difficulties Mostly affects the boys Most are unable to walk by the age of 12	2 to 5 years
Becker	Similar to Duchenne, but less severe Mostly affects the boys Muscle weakness in the appendages Muscle cramps and frequent falls Walking on the toes Learn to walk late	11-15 years
Facioscapulohumeral	Weakness in facial muscles and the muscles found in the shoulder, chest, and upper arms Slow progression, but suddenly shows a rapid period of deterioration Inability to press their lips or to completely shut their eyes	Adolescence to early adulthood
Myotonic	Muscle spasms Myotonia (muscle stiffness) Affects facial muscles- causes drooping of eyelids Weakness in neck muscles resulting in a swan-like neck (difficulty in lifting the neck) Poor vision due to cataract Endocrine disorders affecting the adrenal and thyroid glands Learning disorders Irregular heartbeat	20 to 30 years
Limb-girdle	Loss of muscle mass The pectoral and pelvic girdles are affected Difficulty in climbing stairs and getting up from a chair Most die due to cardiac and pulmonary complications	Late childhood to middle ages
Oculopharyngeal	Affects muscles of the eyelids, throat, and shoulder Drooping eyelids Dysphagia (problem in swallowing) leads to starvation Problems regarding vision Change in voice	40 to 50 years
Distal	Weakness and loss of muscles of both upper and lower limbs. Loss of fine motor skills Difficulty in walking Slow progression	40 to 60 years
Emery-Dreifuss	Weakness of the shin muscles and the muscles in the shoulder, upper arm. Limited joint movement due to tightened tendons Muscles shortened Respiratory and cardiac problems Sudden death from cardiac issues	Childhood to early teens
Congenital	Poor motor control Scoliosis Joint deformities Dysphagia Problems in vision, speech, and intellect Respiratory problems Shortened lifespan	Since birth

Treatment of Muscular Dystrophy

There is no known cure for muscular dystrophy. The available treatments[b] help in managing the condition by controlling the symptoms and slowing the progression. These include:

Physical therapies like yoga and low-intensity exercises help to prevent contractures.
High dietary intake of protein and antioxidants.
Corticosteroid medications for strengthening the muscles.
Corrective surgeries to improve cataract, dysphagia, and cardiac issues.
Medications like ataluren, phenytoin, mexiletine, and others, to reduce symptoms or slow disease progression.

Moreover, research is ongoing on how to use stem cells to regenerate muscle tissues in MD.

Frequently Asked Questions (FAQs)

Q1. How to prevent Muscular Dystrophy?

Muscular Dystrophy is inherited from the predecessors, caused by a genetic mutation. Thus, if there is a family history of MD, and a person is expected to be affected, there is no way to prevent it. However, genetic counselling and prenatal testing help assess risk.

Q2. Why is it so difficult to find a cure for Muscular Dystrophy?

Muscle is a tissue that forms post-mitotically. Thus, even if gene therapy is used to halt the loss of dystrophin, the muscle that has already been lost would not be replaced. It also poses challenges while planning and conducting clinical trials.

Q3. How is Muscular Dystrophy disease progression monitored?

Progression is tracked through muscle strength tests, functional assessments, cardiac evaluations, respiratory tests, and sometimes molecular biomarkers to adjust treatment strategies over time.