DNA methylation in diagnostics: State of the art and perspectives

DNA methylation is the most known and studied among the epigenetic modifications; these are chemical modifications occurring on DNA or histone proteins, able at modifying the transcriptional efficiency of genes. DNA methylation consists in the binding of a methyl group (-CH3) on the carbon n. 5 of a cytosine moiety. Recently, it has been demonstrated that methylated cytosines can be further modified to hydroy-methyl-cytosines, but it is still unclear whether this transformation is just a demethylation intermediate or it can retain the functional role of an independent epigenetic modification. At first, DNA methylation has been studied for its physiological role in the regulation of one expression during the different stages of the cell life, particularly during differential and embryogenesis. Then, during the last thirty year, it has been shown that the epigenetic modifications, particularly DNA methylation, are involved in the onset and progression processes of some pathologies. The role of DNA methylation in cancer processes is known since a long time, whereas only recently it becomes evident that this epigenetic modification is a component of some degenerative and aging-associated pathologies, particularly in neurodegenerative and inflammatory processes. Due to the incredible technical advances developed in the last years, it is now possible to study in detail the methylation pattern of a gene sequence with single cytosine resolution, rapidly and with high accuracy and precision. Besides allowing the rapid evolution of our knowledge of the physio-pathological states in which DNA methylation has a functional role, this favourable condition also allows us to consider the possible use of DNA methylation as diagnostic biomarker in different pathologies.