Question

What is Duchenne muscular dystrophy?

Answer 1

Duchenne muscular dystrophy:

1. Duchenne muscular dystrophy (DMD) is a severe muscular disorder caused by the damage or weakening of the muscles.
2. Usually recognized between three and six years of age,it is characterized by weakness and wasting (atrophy) of the muscles of the pelvic area followed by the involvement of the shoulder muscles.
3. Muscle weakness and atrophy spread to affect the trunk and forearms.
4. The disease is progressive and most affected individuals require a wheelchair by the teenage years.
5. Serious life-threatening complications may ultimately develop, including disease of the heart muscle (cardiomyopathy) and breathing (respiratory) difficulties.

Signs & Symptoms:

1. Affected children develop weakness and wasting (atrophy) of the muscles closest to the trunk (proximal muscles) such as those of the upper legs and pelvic area and upper arms and shoulder area.
2. Delays in reaching developmental milestones such as sitting or standing without assistance; toe walking; an unusual, waddling manner of walking (gait); difficulty climbing stairs or rising from a sitting position (Gower’s sign); and repeated falling.
3. Reduced bone density and an increased risk of developing fractures of certain bones, such as hips and spine.
4. By the late teens, weakness and deterioration of the heart muscle (cardiomyopathy)can result in impairment in the ability of the heart to pump blood, irregular heartbeats (arrhythmia), and heart failure.

Causes:

1. It is inherited as an X-linked disease.
2. X-linked genetic disorders are conditions caused by an abnormal gene on the X chromosome and manifest mostly in males.
3. Females that have a defective gene present on one of their X chromosomes are carriers for that disorder. Carrier females usually do not display symptoms because females have two X chromosomes and only one carries the defective gene. Males have one X chromosome that is inherited from their mother and if a male inherits an X chromosome that contains a defective gene he will develop the disease.