Myopathy is seen in all except
**Core Concept**
Myopathy refers to a group of muscle disorders characterized by muscle weakness and wasting, typically resulting from impaired muscle protein synthesis or degradation. This can be due to various causes, including genetic mutations, environmental toxins, or autoimmune responses.
**Why the Correct Answer is Right**
The correct answer is based on the understanding that myopathy can result from various underlying mechanisms, such as impaired calcium ion release from the sarcoplasmic reticulum, abnormal protein folding, or autoimmune-mediated muscle damage. For example, in Duchenne muscular dystrophy, a genetic mutation leads to the absence of dystrophin, a crucial protein for muscle function.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because myopathy is indeed seen in conditions where there is impaired muscle protein synthesis, such as in muscular dystrophies.
**Option B:** This option is incorrect because myopathy can result from autoimmune responses, such as in myasthenia gravis, where autoantibodies target acetylcholine receptors.
**Option C:** This option is incorrect because myopathy is also seen in conditions where there is abnormal protein folding, such as in inclusion body myositis.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that myopathy can manifest in various forms and can be caused by a wide range of underlying mechanisms. A thorough diagnostic workup is necessary to identify the underlying cause of myopathy, which guides treatment and management.
**Correct Answer: D.**