Muscular dystrophy

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 30, 2016
StartDiseasesMuscular dystrophy

Muscular dystrophy (MD) is a group of diseases that weaken the muscles, and as time goes by the condition gets worse. It is caused by genetic mutations. The most prevalent form of the illness in children is Duchenne muscular dystrophy (DMD). It mostly affects males. Another form of the disease that affects male children is Becker’s muscular dystrophy (BMD).

Contents

Definition & Facts

Muscular dystrophy is most often hereditary. It is a condition where the muscles gradually weaken and deteriorate over time. Genetic mutations inhibit proteins needed to form healthy muscles. According to the Centers for Disease Control and Prevention, DMD affects one in 3,500 live male births. Male children get diagnosed with DMD as early as five years old. The same statistical data indicates that BMD affects one in 18,500 live male births. 

Myotonic muscular dystrophy (which is also referred to as myotonic dystrophy, MMD, and DM) is the most common form of muscular dystrophy that is diagnosed in adults. In addition to causing muscle weakening, a subtype of MMD may cause learning disabilities. There are two types of MMD: MMD1 (DM1) and MMD2 (DM2).

Symptoms & Complaints

The most common symptom of MD is the gradual deterioration of muscles. The signs of muscular dystrophy vary depending on age and the type of MD. Most people affected by the condition have Duchenne muscular dystrophy (DMD). The earliest signs of DMD occur between the ages of two and three. Symptoms of DMD include:

The symptoms of Becker’s muscular dystrophy (BMD) are similar to that of DMD, but they are milder and do not develop as quickly as DMD. The signs of the condition will start to show in teenagers, but they evolve in the mid-twenties or older. Patients with myotonic muscular dystrophy - MMD - tend to develop sleep apnea in which they stop breathing for a few seconds while asleep during the night. Additional symptoms of MMD include:

Symptoms of MMD that first appear in children after infancy and before adolescence may include behavioral problems and cognitive impairments. They may be unable to make decisions or plan future tasks. They also have difficulties organizing visual information and making them meaningful. Moreover, children suffering from MMD tend to be very shy. 

Infants with congenital MMD may have severe cognitive disabilities. The symptoms include speech problems, hearing problems, and vision problems. Babies tend to have weak muscles, and they may be born with club feet

Causes 

Genetic mutations are the cause of MD, though not all of these mutations are inherited. Some of the genetic mutations occur spontaneously in a female’s egg or the developing embryo. About one-third of male children who are affected by DMD do not have a family history of the illness. Regardless of what causes the genetic mutation, it results in the cells that hold muscle together being unable to perform. The consequence is muscle weakness.

People with MD can inherit the disease in different ways based on the particular type of MD. In cases of DMD, the genetic mutation is located on the X chromosome and is passed down through X-linked dominant inheritance which affects males more than females.

Diagnosis & Tests

The doctor will do a physical examination and obtain a medical history of the patient. He or she then performs the following tests:

  • Enzyme tests. The doctor checks the blood for proteins. If the blood has high levels of creatine kinase, a type of enzyme, it indicates that the patient has a muscle disease
  • Electromyography. The doctor inserts a needle in the muscle to measure electrical activity. If the electrical activity changes the pattern, it could mean the patient has MD. 
  • Genetic testing. The doctor will test the patient’s blood to the see if there are any genetic mutations. 
  • Muscle biopsy. The doctor takes a biopsy or tissue sample by using a hollow needle to make an incision. He or she then analyzes the tissue.
  • Heart-monitoring tests such as electrocardiograms (EKG). This particular test checks the electrical activity of the heart in individuals diagnosed with myotonic muscular dystrophy. 
  • Lung-monitoring tests. The test checks how well the lungs function.

Treatment & Therapy

MD does not have a cure, but doctors use medications, physical therapy, and surgical procedures to treat the condition. Recommended medications and therapies include:

Prevention & Prophylaxis

Because muscular dystrophy is a genetic disorder, there is no way to prevent it. If there is a family history of MD, parents may opt to seek genetic counseling before having any children.