One of the most advanced and promising approaches to the modeling of HD andother neurodegenerative diseases is the use of patient-specific inducedpluripotent stem cells (HD-iPSCs) that endogenously express mutant huntingtin.Protocols for differentiating iPSCs into a phenotype similar to the phenotypeof striatal medium spiny neurons (MSNs) [71-73], the cells mostaffected in HD, have been developed. This evidence concerns the gene HTT and Huntington disease.