Mitochondrial D-loop region methylation differentiates Parkinson’s disease from atypical parkinsonism and Parkinson’s disease dementia

Abstract

Background: Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuron loss and α-synuclein aggregation. Epigenetic mechanisms, including mitochondrial DNA (mtDNA) methylation, have been implicated in PD pathogenesis. Methylation of the mitochondrial displacement loop (D-loop) region may play a role in neurodegenerative processes. Research design and methods: This case study assessed D-loop methylation levels in peripheral blood samples from 37 patients with PD, 18 patients with Parkinson’s disease dementia (PD-D), 26 patients with atypical parkinsonism (APS), and 26 healthy controls (HC). Associations with clinical parameters, sex, and L-dopa treatment were analyzed. Results: D-loop methylation levels were significantly reduced in patients with PD-D and APS compared to PD patients and HC. Methylation levels were not associated with disease duration, clinical variables, sex, or L-dopa treatment. Conclusions: Decreased mitochondrial D-loop methylation in PD-D and APS may reflect disease-specific epigenetic mechanisms rather than clinical characteristics or treatment effects.