GBA1 and Parkinson disease: WB analysis showed a significant increase in the levels of α-synuclein phosphorylated at Ser129 (toxic α-Synuclein) in PD DNCs but not in the gene-corrected cells (Figure 7C), which is consistent with previous reports on the effect of GBA1 mutations (Gegg et al., 2020; Glajch et al., 2021).