The cause of Parkinson’s disease is unknown, however there are a number of genetic and environmental factors being studied as risk factors for the disease. Currently about 5- 10% of PD cases are thought to be monogenic and due to single mutations in genes known to be strongly causative for familial PD such as LRRK2, alpha-synuclein, Parkin, and PINK1. Mutations in other genes are strong risk factors for the development of PD (e.g. mutations in glucocerebrosidase (GBA)). More than 90% of cases are sporadic and are likely due to the interplay of multiple genetic risk factors with environmental exposures. Exposure to certain substances have been shown to increase the risk of PD such as herbicides and pesticides while smoking has been associated with a protective effect.
