GRN and Parkinson disease: The present paper outlines the generation of iPSC and engineered isogenic iPSC lines that mimic mutations associated with Rett- syndrome, Neuronal Ceroid Lipofuscinosis (NCL) and PD by generating isogenic iPSC lines expressing truncated or nonfunctional proteins Αlpha-synuclein (SNCA), Progranulin (PGRN), and methyl-CpG-binding protein 2 (MeCP2).