SYN1 and Parkinson disease: Synaptophilin (SNPH); syntaxins (STX) 1A, 1B, and 3; and synapsins (SYN) 1, 2, and 3 were significantly down-regulated in PD organoids, while non-PD organoids were not- differentially expressed for SYN1 and SYN3 (Figure 4A, Tables S1 and S3).