At the 2019 annual meeting for American Society of Neural Therapy and Repair (ASNTR) a special panel assembled to discuss the future of neurotrophic factor delivery in Parkinson's disease (PD), particularly those factors belonging to the Glial cell line-derived neurotrophic factor family of ligands (GFLs; GDNF and Neurturin). The gene discussed is GDNF; the disease is Parkinson disease.