Duchenne’s muscular dystrophy is a disease of-
**Core Concept**
Duchenne's muscular dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness due to a deficiency in dystrophin, a crucial protein for muscle function and integrity. This condition is caused by a mutation in the dystrophin gene, leading to a lack of functional dystrophin protein.
**Why the Correct Answer is Right**
The correct answer involves the pathophysiology of Duchenne's muscular dystrophy. The dystrophin gene provides instructions for making the dystrophin protein, which is essential for muscle function and helps maintain muscle structure. In Duchenne's muscular dystrophy, the dystrophin gene is mutated, resulting in the production of an abnormal or incomplete dystrophin protein. This leads to muscle damage, progressive muscle weakness, and eventual muscle degeneration. The dystrophin protein plays a vital role in maintaining the integrity of muscle cells, and its deficiency leads to muscle cell damage and death.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because Duchenne's muscular dystrophy is not primarily related to the absence of myostatin, a protein that regulates muscle growth.
**Option B:** Incorrect because Becker's muscular dystrophy is a related condition caused by a different mutation in the dystrophin gene, resulting in a partially functional dystrophin protein.
**Option C:** Incorrect because this option does not accurately describe the underlying cause of Duchenne's muscular dystrophy.
**Clinical Pearl / High-Yield Fact**
Becker's muscular dystrophy, a related condition, typically presents later in life and has a milder course than Duchenne's muscular dystrophy. This is because the partially functional dystrophin protein produced in Becker's muscular dystrophy helps maintain some muscle function, leading to a slower progression of the disease.
**Correct Answer:** D. Dystrophin.