**Core Concept**
Protein misfolding disorders are a group of diseases characterized by the aberrant folding of proteins, leading to their aggregation and deposition in various tissues. This misfolding can result from mutations in the protein sequence, environmental factors, or other molecular mechanisms, ultimately causing cellular dysfunction and disease.

**Why the Correct Answer is Right**
The correct answer is a disorder that does not primarily involve protein misfolding. Protein misfolding disorders, such as **Alzheimer's disease**, **Huntington's disease**, and **Amyotrophic lateral sclerosis (ALS)**, are characterized by the accumulation of misfolded protein aggregates in the brain or other tissues. These aggregates can lead to cellular damage, inflammation, and neuronal loss.

**Why Each Wrong Option is Incorrect**
* **Option A:** **Alzheimer's disease** is a classic example of a protein misfolding disorder, characterized by the accumulation of amyloid-beta plaques and tau protein tangles in the brain.
* **Option B:** **Huntington's disease** is another protein misfolding disorder, caused by an expansion of CAG repeats in the huntingtin gene, leading to the aggregation of mutant huntingtin protein.
* **Option C:** **Amyotrophic lateral sclerosis (ALS)** is a neurodegenerative disorder characterized by the accumulation of misfolded superoxide dismutase 1 (SOD1) protein in motor neurons.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that protein misfolding disorders often share common pathophysiological mechanisms, including protein aggregation, oxidative stress, and mitochondrial dysfunction. Understanding these mechanisms is crucial for developing effective therapeutic strategies.

**Correct Answer:** D.