HD is a hereditary neurodegenerative condition caused by a cytosine–adenine–guanine (CAG) repeat expansion in the HTT gene on the short arm of chromosome 4, with consequent production and accumulation of mutant huntingtin protein, which causes neuronal dysfunction and death.2 It is clinically characterised by a triad of motor dysfunction with involuntary movements and loss of voluntary control, cognitive deterioration and psychiatric problems.2 Here, HTT is linked to Huntington disease.