Although total levels of HDAC4 protein were unchanged between controls and PD GBA-N370S patients (Figure S5B), the downregulation of four of the HDAC4-regulated genes (TSPAN7, ATP1A3, RTN1, and PRKCB) in PD GBA-N370S patient-derived neurons was experimentally confirmed (Figure S5C). Here, RTN1 is linked to Parkinson disease.