Compared to AD, Huntington's disease (HD) is a rare (∼ 5/100,000) neurodegenerative disorder exhibiting cognitive dysfunction and severe motor impairments that arises as a result of dominant mutations within the Huntingtin gene (HTT), causing expansion of a polyglutamine region within the HTT protein (Roze et al, 2010). The gene discussed is HTT; the disease is Alzheimer disease.