Final answer:
The dystrophin gene mutation can lead to Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD), both of which are forms of muscular dystrophy resulting in progressive skeletal muscle weakness.
Step-by-step explanation:
Mutations in the dystrophin gene cause phenotypes associated with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). Both of these are forms of muscular dystrophy, which is a group of genetic disorders characterized by progressive skeletal muscle weakness and death of muscle cells and tissues.
DMD is the most common type of childhood muscular dystrophy and is an X-linked recessive disorder that occurs mostly in males. It leads to a progressive weakening of the skeletal muscles due to a lack of dystrophin, a protein that helps muscle fibers bind to the sarcolemma. This deficiency results in muscle damage and degradation over time. BMD is a milder form of muscular dystrophy compared to DMD and is also caused by mutations in the dystrophin gene. However, patients with BMD typically have a partially functioning dystrophin protein, which leads to later onset and slower progression of muscle weakness.
Therefore, the correct answer to this question is D, Both A and B, indicating that both Duchenne and Becker muscular dystrophies are phenotypes caused by mutations in the dystrophin gene.