Muscular dystrophies

Duchenne muscular dystrophy (DMD) is the most common and most rapidly progressive muscular dystrophy, with most patients losing the ability to walk by 12 years of age and requiring ventilatory support by 25 years of age.

Before the use of cardioprotective drugs and respiratory muscle aids, respiratory complications were responsible for 80% of deaths and cardiac complications were responsible for approximately 20%. Survival past 30 years of age is no longer rare, with 10% to 40% of patients with DMD surviving to age 40 in centers that use noninvasive means of respiratory support.

The development of acute respiratory failure, previously considered inevitable, can be preventable for most patients.

Severe scoliosis and the need for corrective surgery can be avoided, and the need for mechanical ventilation delayed, by early and aggressive use of corticosteroids.

With few exceptions, all generalized muscle disease can be managed using the principles for managing DMD.

Muscular dystrophies are progressive, generalized diseases of muscle, most often caused by defective or specifically absent glycoproteins (e.g., dystrophin) in the muscle membrane. All muscular dystrophies are characterized by ongoing degeneration and regeneration of muscle fibers. The most common and rapidly progressive muscular dystrophy is Duchenne muscular dystrophy (DMD). This is X-linked and diagnosed by the finding of absent dystrophin on muscle biopsy. Other X-linked muscular dystrophies include Becker muscular dystrophy (BMD), which is characterized by diminished quantity or quality of dystrophin in muscle biopsy specimens. BMD is a milder form of DMD. Diagnosis can be confirmed using multiplex ligation-dependent probe amplification or full sequencing of the dystrophin gene. This topic will mainly discuss DMD.