Since brain-derived neurotrophic factor (BDNF) induces neuronal survival and tissue repair, it is a promising therapeutic agent for the treatment of neurodegenerative diseases e.g. Alzheimer’s disease in which cholinergic neurons are depleted [1]; Parkinson’s disease [2] in which dopaminergic neurons of the substantia nigra are lost and amyotrophic lateral sclerosis [3] (ALS) in which cerebral and spinal motor neurons degenerate. The gene discussed is BDNF; the disease is Parkinson disease.