Published online by Cambridge University Press: 05 March 2022
Parkinson’s disease (PD) has long been considered as a prototype of a sporadic disorder with little or no involvement of genetic factors. Three to four decades ago, the typical perception of genetics in PD was that “it appears unlikely that heredity is an important determinant in the development of the disorder” . The discovery of SNCA mutations in 1997  started a new era of genetic studies in PD. We now know of at least 90 independent genome-wide association study (GWAS) risk variants in 78 loci that are associated with sporadic PD . Several other genes that are involved in familial, sporadic PD, or atypical forms of familial parkinsonism, have also been identified (Table 18.1).