Neurotrophins such as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and glial cell line-derived neurotrophic factor (GDNF) are neuronal activity regulators involved in the development and maintenance of the mature nervous system, and as such, they may also contribute to the pathophysiology of schizophrenia [13]. This evidence concerns the gene GDNF and schizophrenia.