Although Htt plays a critical physiological role in early development as well as in post-developmental activities, like axonal trafficking and anti-apoptotic signaling [207], mutant Htt tends to form intranuclear and cytoplasmic aggregates in neurons, especially those in the striatum, which results in cytotoxicity and HD-associated neurodegenerative symptoms [208,209]. This evidence concerns the gene HTT and Huntington disease.