On the basis of our previous results on the neuroprotective and neurorestorative effects of CDNF protein in PD rat and mouse models (Lindholm et al. 2007; Voutilainen et al. 2011; Airavaara et al. 2012), we studied the effect of CDNF gene delivery using an AAV serotype 2 vector encoding CDNF. This evidence concerns the gene CDNF and Parkinson disease.