SNCA and Parkinson disease: Some of these susceptibility variants are listed in Figure 2B. The largest whole genome-association study to date, involving 13,708 PD cases and 95,282 controls, places LRRK2 among the top genes linked to PD susceptibility.12 In consideration of both familial and population studies, apart from α-synuclein (PARK1/4), no other gene shares as strong a relationship to late-onset PD.