Promising applications for human disease modeling include generation of iPSCs derived from methyl CpG binding protein 2 (MeCP2)-deficient patients with RETT syndrome, an autism spectrum disorder, and from a single Parkinson's disease patient harboring a mutation in the leucine-rich repeat kinase 2 gene (LRRK2) [5, 6]. Here, LRRK2 is linked to Rett syndrome.