Re-evaluation of human mitochondrial DNA methylation reveals signals consistent with technical artifacts

The existence and functional relevance of mitochondrial DNA (mtDNA) methylation remain controversial. We assessed 5mC and 5hmC in human brain, blood, and related cancers using both enzymatic and native DNA sequencing. While nuclear DNA exhibited expected methylation patterns, mtDNA consistently showed negligible methylation levels, indistinguishable from technical noise. Elevated methylation in nuclear-embedded mitochondrial sequences demonstrates a clear potential to confound mtDNA methylation measurements. Furthermore, technical discrepancies in mtDNA methylation were observed, underscoring the need for careful evaluation when interpreting data generated using earlier sequencing workflows. Our findings provide evidence against the presence of 5mC or 5hmC in mtDNA under the physiological and pathological conditions studied.

• Type: Whole Genome Sequencing
• Archiver: European Genome-Phenome Archive (EGA)