In particular for monogenic forms of disease, patient-derived iPSCs have already been shown to recapitulate known disease mechanisms, as shown in spinal muscular atrophy [4], fragile X syndrome [5], progeria syndrome [6], and several genetic forms of Parkinson disease (PD) like LRRK2 [7], PINK1 [8], SNCA [9], and GBA [10]. This evidence concerns the gene GBA1 and Parkinson disease.