Gazing into the future: Parkinson's disease gene therapeutics to modify natural history

PD gene therapy clinical trials have primarily focused on increasing the production of dopamine (DA) through supplemental amino acid decarboxylase (AADC) expression, neurotrophic support for surviving dopaminergic neurons (DAN) or altering brain circuitry to compensate for DA neuron loss. The future of PD gene therapy will depend upon resolving a number of important issues that are discussed in this special issue. Of particular importance is the identification of novel targets that are amenable to early intervention prior to the substantial loss of DAN. However, for the most part the etiopathogenesis of PD is unknown making early intervention a challenge and the development of early biomarker diagnostics imperative.