Huntington's disease is best described as which of the following?

• A. A genetic disorder that causes progressive deterioration of brain cells, caused by a dominant allele before age 30
• B. A metabolic disorder affecting the liver
• C. An autoimmune disease affecting the neuromuscular junction
• D. A contagious infection of the brain

Answer: (A)

Huntington's disease is a genetic neurodegenerative disorder inherited in an autosomal dominant pattern. A mutation in the HTT gene causes a progressive loss of neurons in the basal ganglia and cortex, leading to increasingly abnormal movements, cognitive decline, and psychiatric changes. The key takeaway is that it’s a hereditary, dominant condition that produces progressive brain deterioration. The other descriptions don’t fit: it’s not a metabolic liver disorder, not an autoimmune disease at the neuromuscular junction, and not a contagious brain infection. Onset is typically in adulthood (often in the 30s–40s), though juvenile cases can occur.