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Updated: Sep 10, 2025
Methodology for Accurate Detection of Mitochondrial DNA Methylation
Published on: May 20, 2018
Altered mitochondrial DNA methylation in blood in individuals with mild cognitive impairment
Wuzi Tu1, Ying Jin2, Xiaohong Zhang1
1School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Background:
Previous studies reported that altered mitochondrial methylation in Alzheimer's disease (AD), however, whether epigenetic modifications in mitochondrial genomes contribute to preclinical AD remains unclear. This study aimed to investigate mitochondrial methylation changes in individuals with cognitive decline.
Research Design And Methods:
We examined whole mitochondrial genome methylation in 50 individuals with mild cognitive impairment (MCI) and 50 individuals without MCI, using bisulfite amplicon sequencing, assessing methylation at 366 Cytosine-guanine oligodeoxynucleotide (CpG) sites.
Results:
We found the overall methylation level of mitochondrial DNA (mtDNA) in each subject was relatively low, ranging from 0% to 15%. Global methylation was significantly higher in individuals with cognitive decline compared to controls (3.86% vs. 3.46%, p = 0.037), with 34 differentially methylated CpG sites identified. Methylation differences (MD) between cognitive decline individuals and controls were 22.93 ± 5.60% at chrM6465 (Q = 0.013), 12.55 ± 3.02% at chrM9612 (Q = 0.013), 11.45 ± 3.88% at chrM11762 (Q = 0.159) and 11.03 ± 3.88% at chrM11766 (Q = 0.172), respectively, while the level of MD at chrM15812 was -13.11 ± 4.31% (Q = 0.159) after Benjamini-Hochberg FDR adjusted. Furthermore, Methylation at specific sites were significantly correlated with Mini-Mental State Examination scores, distinguishing individuals with cognitive decline from controls.
Conclusions:
Our study provides an mtDNA methylation map and suggests a role for these sites in preclinical AD pathogenesis.
Insights
Mitochondrial DNA (mtDNA) methylation is higher in individuals with cognitive decline, suggesting a role in preclinical Alzheimer's disease (AD). This study maps these epigenetic changes, offering insights into early AD pathogenesis.
Area of Science:
- Epigenetics
- Neuroscience
- Genomics
Background:
- Altered mitochondrial methylation is linked to Alzheimer's disease (AD).
- The role of mitochondrial genome epigenetic modifications in preclinical AD remains unclear.
- This study investigates mitochondrial methylation in individuals experiencing cognitive decline.
Purpose of the Study:
- To examine whole mitochondrial genome methylation patterns in individuals with and without mild cognitive impairment (MCI).
- To identify specific differentially methylated sites in mitochondrial DNA (mtDNA).
- To explore the correlation between mtDNA methylation and cognitive function.
Main Methods:
- Whole mitochondrial genome methylation analysis using bisulfite amplicon sequencing.
- Assessment of methylation at 366 Cytosine-guanine (CpG) sites in 100 participants (50 MCI, 50 controls).
- Statistical analysis including Benjamini-Hochberg FDR adjustment for multiple comparisons.
Main Results:
- Overall mtDNA methylation levels were low (0-15%) but significantly higher in individuals with cognitive decline (3.86% vs. 3.46%, p=0.037).
- 34 differentially methylated CpG sites were identified, with significant methylation differences at chrM6465 and chrM9612.
- Methylation at specific sites correlated with Mini-Mental State Examination scores, distinguishing between cognitive decline and control groups.
Conclusions:
- This study provides a comprehensive map of mtDNA methylation in cognitive decline.
- Specific mtDNA methylation sites are implicated in preclinical Alzheimer's disease pathogenesis.
- mtDNA methylation represents a potential biomarker for early detection of AD.
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