What is the cause of Huntington's disease?

• A. Injury to the brain due to trauma
• B. An inherited condition causing nerve cell breakdown
• C. Environmental toxins affecting brain function
• D. Viral infection leading to cognitive decline

Answer: (B)

Huntington's disease is caused by an inherited condition that results in the degeneration of nerve cells in the brain. Specifically, it is linked to a mutation in the HTT gene, which leads to the production of a faulty form of the huntingtin protein. This mutation triggers a cascade of neurotoxic effects, leading to the progressive breakdown of neurons, particularly in regions of the brain that control movement, cognition, and behavior.

Due to its genetic basis, Huntington's disease follows an autosomal dominant inheritance pattern, meaning that an individual only needs one copy of the mutated gene to develop the disorder. On a cellular level, this degeneration manifests as involuntary movements, psychiatric symptoms, and cognitive decline as the disease progresses.

This genetic etiology is distinct from the other options presented, which focus on factors like physical trauma, environmental toxins, and infections—none of which are associated with the pathology of Huntington's disease. Each of these conditions, while they may affect brain function or lead to cognitive issues, do not share the same hereditary basis or specific neurodegenerative mechanisms as Huntington's disease.