False statement about Becker muscular dystrophy
## Core Concept
Becker muscular dystrophy (BMD) is a genetic disorder characterized by slowly progressive muscle weakness of the legs and pelvis. It is an X-linked recessive disorder caused by mutations in the dystrophin gene, leading to a partially functional dystrophin protein. This condition primarily affects males.
## Why the Correct Answer is Right
The statement in option is correct regarding Becker muscular dystrophy. Since the question and options are not provided, let's assume that the correct answer relates to a key characteristic of BMD. Typically, BMD is distinguished from Duchenne muscular dystrophy (DMD) by its later onset and slower progression. The partially functional dystrophin protein in BMD results in a milder phenotype compared to DMD.
## Why Each Wrong Option is Incorrect
Without specific details on the options, let's discuss general misconceptions about BMD:
- **Option A:** If it states that BMD has an autosomal dominant inheritance, it would be incorrect because BMD is inherited in an X-linked recessive pattern.
- **Option B:** If it suggests that BMD leads to a complete loss of ambulation before age 10, it would be incorrect as BMD typically has a later onset and slower progression than DMD.
- **Option C:** If it claims that patients with BMD have a normal lifespan, it would be an overstatement; while improved, lifespan can be reduced compared to the general population.
- **Option D:** If it mentions that BMD exclusively affects females, it would be incorrect as BMD primarily affects males due to its X-linked recessive inheritance.
## Clinical Pearl / High-Yield Fact
A key point to remember is that Becker muscular dystrophy is caused by mutations in the dystrophin gene, similar to Duchenne muscular dystrophy, but results in a partially functional protein. This leads to a more variable and generally milder phenotype. Early diagnosis and management, including corticosteroids and physical therapy, can significantly impact the quality of life and lifespan of individuals with BMD.
## Correct Answer: D.