Mitochondrial DNA methylation as a next-generation biomarker and diagnostic tool

Recent expansion of our knowledge on epigenetic changes strongly suggests that not only nuclear DNA (nDNA), but also mitochondrial DNA (mtDNA) may be subjected to epigenetic modifications related to disease develop- ment, environmental exposure, drug treatment and aging. Thus, mtDNA methylation is attracting increasing attention as a potential biomarker for the detection and diagnosis of diseases and the understanding of cellular behavior in particular conditions. In this paper we review the current advances in mtDNA methylation studies with particular attention to the evidences ofmtDNAmethylation changes in diseases and physiological conditions so far investigated. Technological advances for the analysis of epigenetic variations are promising tools to provide insights intomethylation ofmtDNA with similar resolution levels as those reached for nDNA. However,many aspects related tomtDNAmethylation are still unclear. More studies are needed to understand whether and how changes in mtDNA methylation patterns, global and gene specific, are associated to diseases or risk factors.