Safety Study of AADC Gene Therapy (VY-AADC01) for Parkinson's Disease

Inclusion Criteria: * Diagnosed with idiopathic Parkinson's disease * Disease duration of at least 5 years or more * Adequate duration of levodopa therapy * Modified Hoehn and Yahr Staging of at least 2.5 in the OFF state * Candidate for surgical intervention because of disabling motor complications. * UPDRS Part III (total motor) score ≥ 25 and a maximum of 60 in the OFF state. * Unequivocal responsiveness to dopaminergic therapy. * Stable Parkinson's symptoms and medication regimen for at least 4 weeks prior to screening examination. * Ability to comprehend and sign the informed consent. * Normal Laboratory values prior to surgery. * Neutralizing AAV2 antibody titer ≤ 1:1200 * Ability to travel to study visits alone or able to designate a caregiver. * Subject agrees to defer any neurological surgery, including deep brain stimulation, until after completing the 12 month study visit (unless recommended by study neurologist). * Subject agrees to not participate in any other therapeutic intervention study for 12 months after surgery. * Subject agrees to not have any vaccinations within 30 days of surgery. Exclusion Criteria: * Atypical or secondary parkinsonism, including but not limited to symptoms believed to be due to trauma, brain tumor, infection, cerebrovascular disease, other neurological disease, or to drugs, chemicals or toxins. * Presence of dementia as defined by a Mattis Dementia Rating Scale-Second Edition (MDRS-2) of less than 130 at screening. * Presence or hi…