DDC and Parkinson disease: On a positive note, gene therapy approaches are being currently explored and showed some effectiveness in clinical trials as an alternative to pharmacological treatment of neurodegenerative diseases, such as PD44, 45, 46, 47; in one open label-study, gene therapy was proven to be tolerable and safe in patients with Parkinson’s Disease followed for 2 years46, and applications in pediatric patients lead to positive outcomes, such is the case of Aromatic Amino Acid Decarboxylase (AADC) deficiency48, 49.