HTT and Huntington disease: HD is a relatively rare neurodegenerative disease, with an average prevalence of 4.88 per 100,000 individuals.199 HTT gene mutations trigger a cascade of molecular events, including transcriptional dysregulation, impaired protein homoeostasis, and disrupted intracellular transport.200 These abnormalities are compounded by age-related decreases in cellular repair mechanisms and increased oxidative stress.