PD‐1101 is an open‐label, phase I, dose‐escalation trial of AADC gene therapy in patients with moderately advanced PD utilizing intraoperative magnetic resonance imaging–guided putaminal administration of VY‐AADC01, an AAV2 vector for the delivery of the gene encoding the AADC enzyme. The gene discussed is DDC; the disease is Parkinson disease.