**Core Concept**
Huntington's disease is a progressive neurodegenerative disorder characterized by motor dysfunction, cognitive decline, and psychiatric symptoms. It is caused by an expansion of a CAG repeat in the Huntingtin gene, leading to a toxic protein that causes neuronal damage and death.

**Why the Correct Answer is Right**
Huntington's disease is an autosomal dominant disorder, meaning that a single copy of the mutated gene is sufficient to cause the condition. The disease typically presents in mid-life, with symptoms including chorea (involuntary movements), rigidity, and cognitive decline. The pathophysiology involves the formation of protein aggregates that disrupt neuronal function and lead to cell death. The CAG repeat expansion in the Huntingtin gene is a hallmark of the disease and is used for genetic diagnosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true, as Huntington's disease is indeed characterized by progressive motor dysfunction, including chorea, rigidity, and bradykinesia.
**Option B:** This statement is also true, as cognitive decline is a common feature of Huntington's disease, affecting memory, attention, and executive function.
**Option C:** This statement is true, as psychiatric symptoms, including depression, anxiety, and psychosis, are common in Huntington's disease.

**Clinical Pearl / High-Yield Fact**
The CAG repeat expansion in the Huntingtin gene is a key diagnostic feature of Huntington's disease, and genetic testing is available for individuals with a family history of the condition.

**Correct Answer: A. This statement is false regarding Huntington's disease, as it is a polyglutamine disorder, not a prion disorder.**