Duchenne muscular dystrophy
What is Duchenne Muscular Dystrophy?
Duchenne muscular dystrophy (DMD) is a genetic disorder, which involves quickly worsening muscle weakness. Other muscular dystrophies get worse much more slowly. Duchenne muscular dystrophy is caused by a defective gene for dystrophin (a protein in the muscles), and often occurs in people without a known family history of the condition. The disease primarily affects boys, but in rare cases it can affect girls.
Signs and symptoms
DMD symptom onset is in early childhood, usually between ages 2 and 3. Muscle weakness is the principal symptom of DMD. It can begin as early as age 2 or 3, first affecting the proximal muscles (those close to the core of the body) and later affecting the distal limb muscles (those close to the extremities). Usually, the lower external muscles are affected before the upper external muscles. The affected child might have difficulty jumping, running, and walking. Other symptoms include enlargement of the calves, a waddling gait, and lumbar lordosis (an inward curve of the spine). Later on, the heart and respiratory muscles are affected as well. Progressive weakness and scoliosis result in impaired pulmonary function, which can eventually cause acute respiratory failure.
Children with Duchenne muscular dystrophy
Due to the way the disorder is inherited, the condition most often affects boys and only rarely girls. The sons of women who are carriers of the disorder each have a 50% chance of having the disorder. The daughters each have a 50% chance of being carriers. In Europe and North America, the prevalence of DMD is approximately 6 per 100,000 individuals.
Diagnosis of Duchenne muscular dystrophy
Until relatively recently, boys with DMD usually did not survive much beyond their teen years. Thanks to advances in cardiac and respiratory care, life expectancy is increasing and many young adults with DMD attend college, have careers, get married, and have children. Survival into the early 30s is becoming more common than before.