The same differentiation process was used to generate end stage macrophages from isogenic iPSCs engineered to mimic mutations associated with Parkinson’s disease (SNCA A53T), neuronal ceroid lipofuscinosis (GRN2/GRN R493X), and Rett syndrome (MECP2-Knockout). The gene discussed is GRN; the disease is infantile neuronal ceroid lipofuscinosis.