Study of Methylation Levels of Parkin Gene Promoter in Parkinson's Disease Patients

Mutations in the parkin gene have been significantly linked to autosomal recessive juvenile parkinsonism (ARJP). In addition to its association with ARJP, loss of heterozygosity of parkin has been found in several types of malignant tumors, including ovarian, breast, and hepatocellular tumors. Abnormal methylation of parkin promoter was observed in patients with acute lymphoblastic leukemia and chronic myelogenous leukemia in lymphoid blast crisis. We hypothesized that hypermethylation of the parkin promoter might reduce the expression of parkin, which would contribute to the pathogenesis of parkinson's disease (PD) in idiopathic patients and parkin heterozygotes. In this study, we analyzed samples from 17 PD patients with heterozygous parkin mutations, 17 PD patients without parkin mutations, and 10 normal controls. We determined the levels of methylation of the parkin gene promoter in each group using bisulfite genomic sequencing of a region containing 33 CpG sites in the CpG island of the parkin promoter. The methylation levels indicated hypomethylation, and there were no significant differences in the incidence of CpG site methylation among three groups (P > 0.05). These results suggest that the methylation mechanism is unlikely to play a role in the pathogenesis and development of PD.