Becker Muscular Dystrophy is best described by which dystrophin status?

• A. No dystrophin
• B. Overexpression
• C. Partial dystrophin
• D. Normal dystrophin

Answer: (C)

Becker muscular dystrophy is characterized by dystrophin that is reduced in amount and truncated in size, not completely absent. This happens because the mutations are in-frame deletions in the dystrophin gene, allowing a shorter but still partly functional dystrophin protein to be produced. Having some dystrophin at the muscle membrane helps stabilize the fiber during contraction, so damage is less severe than when dystrophin is entirely missing. That partial, rather than absent, dystrophin level explains why Becker tends to have a later onset and slower progression compared with Duchenne muscular dystrophy, where dystrophin is absent.