LRRK2 and Parkinson disease: To identify methylation of α-synuclein (SNCA) and leucine-rich repeat kinase 2 (LRRK2) in leukocytes in PD, bisulfite specific PCR-based sequencing was used to detect methylation of CpG islands in the promoter (CpG-1) and intron 1 (CpG-2) of SNCA and LRRK2. Although there were no methylation differences in CpG-1 of SNCA or the LRRK2 promoter, the second, fourth, and ninth CpG sites of the 14 CpG sites of CpG-2 were significantly hypomethylated in patients with PD.