As mentioned above, most studies of GDNF/GFRA1 signaling are related to neurodegenerative (Parkinson’s disease and Alzheimer’s disease) and neuropsychiatric diseases (addiction, bipolar disorder, obsessive compulsive disorder, depression, anxiety, autism, schizophrenia, and attention deficit hyperactivity disorder). The gene discussed is GDNF; the disease is Parkinson disease.