Huntington disease (HD) is an inherited neurodegenerative disorder caused by a defect on chromosome four where, within the Huntingtin gene, a CAG repeat occurs too many times. Most individuals begin experiencing symptoms in their 40s or 50s, but studies have shown that significant brain atrophy occurs several years prior to an official HD diagnosis. As a result, the field has sought a preventive treatment that could be administered prior to the development of actual symptoms that might delay the onset of illness.