Which of the following describes Huntington's disease?

• A. Primary problem: Genetic neurodegeneration; Brain areas: Basal ganglia (caudate & putamen)
• B. Primary problem: Demyelination in CNS
• C. Primary problem: Loss of dopamine neurons
• D. Primary problem: Autoimmune attack on myelin

Answer: (A)

Huntington’s disease is a genetic neurodegenerative disorder that primarily targets the basal ganglia, especially the caudate and putamen. The disease stems from a CAG repeat expansion in the HTT gene and is inherited in an autosomal dominant pattern. The key feature is loss of the GABAergic medium spiny neurons in the striatum, which disrupts the balance of the direct and indirect motor pathways. This disruption leads to excessive thalamocortical excitation and the characteristic involuntary, jerky movements (chorea), along with cognitive and psychiatric symptoms as the disease advances. Pathologically, you see atrophy of the caudate and putamen and enlargement of the lateral ventricles due to striatal loss. So this option best fits Huntington’s disease, distinguishing it from demyelinating diseases like multiple sclerosis, dopaminergic neuron loss seen in Parkinson’s disease, or autoimmune attacks on myelin.