DDC and Parkinson disease: In a phase I/II clinical trial, tyrosine hydroxylase (TH), aromatic amino acid dopa decarboxylase (AADC), and GTP-cyclohydroxylase-1 (GCH-1) expressed from LV vectors (ProSavin) were subjected to intrastriatal administration in Parkinson’s disease patients, which was safe, well tolerated, and provided significant improvement of motor function [219].