An introduction to the molecular events that underlie the normal function of the nervous system, with a focus on the origins of neuronal diseases including neurodevelopmental disorders (e.g. autism, intellectual disability), neurodegenerative diseases (e.g. Parkinson's, Alzheimer's) and neuro-immune disorders (e.g. Multiple sclerosis). Molecular and genetic approaches for the study of these disorders as well as therapeutic approaches and ethical aspects are discussed.