Parkinson disease and related disorders

Abstract Advances in genetic technology have revealed new information about the genetics of Parkinson disease (PD) and related disorders. While numerous genes have been associated with PD, a limited number have been proven to be causal. Mutations in three autosomal dominant genes (SNCA, LRRK2, and VPS35) and seven recessive genes (Parkin, PINK1, DJ1, FBXO7, DNAJC6, ATP13A2, and PLA2G6) are definitively pathogenic. Despite all these findings, the great majority of PD cases are not due to monogenic etiology. Many genetic risk factors have been linked to PD, of which GBA is recognized as the most important. This chapter reviews the current information about the genetics of PD and related disorders, including emerging evidence on genotype–phenotype correlations and biological mechanisms of disease. This information will assist in prognosis and identify pathways for treatment. Yet, because of the complexity of genetic information, genetic counseling is strongly recommended before and after testing.