Moreover, with the use of DD-ecDHFR/TMP, Quintino and collaborators were able to control the level of glial cells-derived neurotrophic factor (GDNF), a protein that exerts neurotrophic and neuroprotective effects on dopamine neurons, in a rodent model of Parkinson's disease (Quintino et al., 2013) confirming the great therapeutic potential of GDNF against Parkinson's disease. This evidence concerns the gene GDNF and Parkinson disease.