GBA1 and Parkinson disease: Using PD patient fibroblasts harboring mutant GBA1, we generated human iPSCs and their isogenic controls by CRISPR-Cas916 (Supplementary Fig. 1a) which were subsequently differentiated into midbrain dopaminergic neurons (mutant GBA1 (∆GBA); isogenic control (Corr)) (Supplementary Fig. 2a–c).