Muscular Dystrophy Types & Causes of Each Form

Muscle weakness remains the prime symptom of muscular dystrophy.

Muscle weakness remains the prime symptom of muscular dystrophy. Depending on the type, the onset of disease varies. Other common signs of muscular dystrophy include:

• Scoliosis (sideways curved spine)
• Enlarged calf muscle
• Difficulty in walking or running
• Dysphagia (difficulty swallowing)
• Muscle pain
• Learning disabilities
• Stiff or loose joints
• Breathing problems
• Waddling (abnormal  gait)
• Cardiomyopathy (disease of the heart muscle)
• Arrhythmia
• Heart failure

Muscular dystrophies are a group of genetic diseases causing progressive weakness and loss of muscle mass.  There are more than 30 types of muscular dystrophy that result in muscle weakness. Over time, the muscles get weaker, disturbing the gait (a person’s manner of walking) and the ability to perform daily activities. 

Some forms of muscular dystrophy may be present at birth and develop during childhood, while other forms develop during adulthood.  Muscular dystrophy can be hereditary.

Here are the different types:

1. Duchenne Becker (DMD): The onset of this type is between the ages of two and five years. It occurs due to a mutation in the gene for a muscle protein called dystrophin. DMD is the most common form of muscular dystrophy.
2. Becker (BMD): It is the second most common form of muscular dystrophy and affects the hip, thigh, and shoulder muscles. The symptoms and causes are similar to DMD. BMD symptoms begin later in life and generally are less severe as compared to DMD.
3. Myotonic dystrophy: In this type, the person faces difficulty in relaxing their muscles. It typically begins between 10-30 years of age but can affect people of all ages. It can affect the heart and lungs.
4. Limb-Girdle muscular dystrophy: This type of muscular dystrophy affects the muscle of the shoulders and hips. It affects people of all ages and approximately affects two out of 100,000 people in the U.S.
5. Facioscapulohumeral muscular dystrophy: It is the third most common form of muscular dystrophy. The disease affects muscles in the face, shoulder blades, and upper arms. The onset of this type is before 20 years of age.
6. Congenital muscular dystrophy: This may be present at birth resulting in weak muscles, curved spine, and stiff or loose joints in infants. Children may also face learning disabilities, seizures, and vision problems.
7. Distal muscular dystrophy: This type of muscular dystrophy typically begins in adulthood. It affects the feet, hands, lower legs, and lower arms. It can also affect the heart
8. Oculopharyngeal muscular dystrophy: It is the rare form of muscular dystrophy that affects the muscles in the eyelid and throat. The symptoms such as droopy eyelids (ptosis) and difficulty swallowing usually appear between the 40s and 60s. 
9. Emery-Dreiffuss muscular dystrophy: It mostly affects children. Children may experience weak shoulders, upper arms, and calf muscles, by the age of 10.

Most of the muscular dystrophy occurs due to genetic mutations. One or both parents may pass faulty genes to the child. Idiopathic muscular dystrophy or dystrophy with an unknown cause is rare.

Muscular dystrophy often runs in families. A child may inherit the mutated genes from one or both the parents. Parents with mutated genes and without muscular dystrophy may pass the genes to the child, thus increasing the risk of developing the disease.