Duchenne Muscular Dystrophy


Duchenne muscular dystrophy (DMD) characterized by muscle weakness and progressive muscle degeneration caused due to genetic disorder. The absence of dystrophin which keeps the muscle cells intact causes DMD. It affects kids more, especially boys compared to girls. Mutations in the DMD gene causes DMD. DMD is inherited from a recessive X chromosome. However, it also occurs in people who do not have a family history of DMD. DMD affects learning and memory, as well as communication and certain social emotional skills. Muscle weakness worsens with age as it progresses to the arms, legs, and trunk. Heart and respiratory muscles problems begin in the teen years and it will lead to life threatening complications.

What are the Symptoms of DMD?

The symptoms of DMD are as follows:

  1. Muscle weakness as early as 3 years of age. By age 10, braces are required for walking. By age 13, a wheelchair is required. The average age for walking in affected boys is 18 months.
  2. Affects the muscles on the hips, thighs, pelvic area and shoulders.
  3. Also the skeletal muscles in the arms, legs and trunk are get affected
  4. The heart and respiratory muscles are affected in teen ages.
  5. Waddling walk and difficulty climbing stairs or running.
  6. Enlarged calf muscles causing calf pain.
  7. The joints become rigid and tight as muscle loss progresses. Finally, it restricts mobility and flexibility.
  8. Breathing problems occur due to weakness of the diaphragm
  9. Cardiomyopathy
  10. Cognitive impairment
What Causes DMD?

Researchers have identified that a mutation in a particular gene on the X chromosome leading to DMD. This gene is transcribed and translated into a protein called dystrophin. Loss or absence of dystrophin protein in muscle cells causes the muscles to become fragile and get easily damaged. DMD female carriers are with normal dystrophin gene and an abnormal dystrophin gene on both of the two X chromosomes. Even though the women themselves do not have any signs or symptoms of the disease, they transfer it in an X-recessive pattern to the offspring. Boys who are suffering with DMD usually do not survive beyond teen years.

How is DMD Diagnosed?

A pediatrician diagnoses DMD by observing the child for signs and symptoms of DMD such as progressive muscle weakness, family history is studied. Blood tests are performed to study the presence of specific proteins, such as serum creatine phosphokinase, that could have leaked from the damaged muscles. A change in the DMD gene when determined through genetic testing confirms the diagnosis of DMD. Diagnosis using Electromyography can also detect DMD.

How is DMD Treated

There is no cure for DMD, though research is still continuing. Treatment is used to control the symptoms of DMD and related complications. Assistive devices for breathing difficulties is used as and when the disease progresses.

Gentle exercise is prescribed. Physical inactivity worsens muscle disease.

Steroids help in improving the strength and function of the muscles, though the possible side effects include weight gain, high blood pressure, behavior changes, and delayed growth. Chronic use of corticosteroids leads to side effects, and thus, rapid withdrawal of corticosteroids can result in life-threatening complications.

Stem Cell Therapy for DMD

Stem cell therapy is tested and appreciated to treat this genetic disorder. Stem cells aid in regenerating and repairing the damaged muscle cells. Stem cells having the ability to differentiate into any kind of cells are used to deliver functional muscle proteins. These cells help counteract muscular dystrophy.

Transplanted cells have myogenic potential to differentiate into a mature myocyte, thereby having the ability to repair and regenerate muscle fibers. Stem cells secrete various anti-inflammatory cytokines and growth factors that are also myo-protective.