Gene-targeting approaches for movement disorders: recent advances.

To summarize the current state of art of gene therapy for Parkinson's disease. Introduction of the gene for glutamic acid decarboxylase (GAD) into the subthalamic nucleus was successful in a randomized, double-blind clinical trial and recent data from PET imaging identified novel brain networks underlying both sham surgery and therapeutic responses in treated participants. Two other approaches use viral vectors to increase dopamine transmission in the striatum. Both strategies are being studied in active trials and have recently reported promising responses in human participants. New strategies in Parkinson's disease are focused upon targeting the underlying pathogenesis in those with genetic defects thought to be the cause of disease. Finally, noninvasive focused ultrasound is currently being tested for lesioning in Parkinson's disease patients, but this same technology can be used to transiently open the blood-brain barrier, raising the potential for noninvasive delivery of gene therapy vectors to specific brain targets. Parkinson's disease gene therapy has moved from purely animal research three decades ago, to initial human studies two decades ago to many applications moving into late stage trials, currently. Recent successes and promising new technology should only accelerate the advance of gene therapy into active clinical practice.