**Core Concept**
Huntington's disease is a progressive neurodegenerative disorder characterized by an autosomal dominant inheritance pattern, with a pathognomonic feature of chorea, 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 dysfunction and death.

**Why the Correct Answer is Right**
The correct answer is that Huntington's disease is characterized by a loss of neurons in the caudate nucleus and putamen, leading to a reduction in striatal volume. This is a result of the toxic protein's effect on the brain's basal ganglia circuitry, causing an imbalance in the dopamine and acetylcholine systems. The disease's hallmark feature, chorea, is thought to result from the disruption of normal motor control pathways.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Huntington's disease is not caused by a deficiency of the neurotransmitter dopamine. In fact, the disease is characterized by an overactivity of the dopamine system in the basal ganglia.
* **Option B:** This option is incorrect because Huntington's disease is not primarily associated with frontotemporal dementia. While cognitive decline is a feature of the disease, it is not as prominent as the motor symptoms.
* **Option C:** This option is incorrect because Huntington's disease is not caused by a viral infection. The disease is a genetic disorder caused by a mutation in the Huntingtin gene.

**Clinical Pearl / High-Yield Fact**
A key feature of Huntington's disease is the presence of a "corkscrew" or "tiger-tail" appearance on T2-weighted MRI scans, which reflects the atrophy of the caudate nucleus and putamen.

**Correct Answer: A. This option is incorrect because Huntington's disease is not caused by a deficiency of the neurotransmitter dopamine.**