In addition to the increased pro-inflammatory mediators in the brain in neurodegenerative diseases, neurotrophic factors, such as brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF) and insulin-like growth factor (IGF)-1, are impaired in these diseases [3,4,5,6,7,8,9,10,11]. The gene discussed is GDNF; the disease is neurodegenerative disease.