July 27, 2016

DNA methylation assays as epigenetic biomarkers

Quantitative comparison of DNA methylation assays for biomarker development and clinical applications

A new milestone has been achieved in Medicine. Tracking epigenetic alterations is crucial to understand a disease. However, epigenetic biomarkers are needed to assess such changes. Its precision (sensitivity-specifity) is  paramount for its clinical application. Now a group of international researchers has certified its performance (partially). Have a look at this Nature article:
Genome-wide mapping and analysis of DNA methylation has become feasible for patient cohorts with thousands of samples, and epigenome-wide association studies have been conducted for numerous biomedically relevant phenotypes. To translate relevant epigenome associations into clinically useful biomarkers, it is necessary to select a manageable set of highly informative genomic regions, to target these loci with DNA methylation assays that are sufficiently fast, cheap, robust and widely available to be useful for routine clinical diagnostics, and to confirm their predictive value in large validation cohorts.
Among its conclusions I would like to highlight three of them:
(i) Absolute DNA methylation assays are the method of choice when validating DNA methylation differences in large cohorts, and they are also an excellent technology for developing epigenetic biomarkers.
(ii) Relative DNA methylation assays are not a good replacement for absolute assays. However, experiences of scientists in the contributing laboratories suggest that carefully selected, designed and validated relative assays can cost-effectively detect minimal  races of methylated DNA against an excess of unmethylated DNA.
(iii) Global DNA methylation assays suffer from noisy data and divergent results between technologies. Locus-specific assays (possibly combined with prediction) provide a more robust alternative
That's it. Very soon will see the epigenetic biomarkers in routine clinical use. And afterwards,  epigenetic drugs and treatments. Then, we'll confirm that the promise of precision medicine is a reality. The implications for medicine as a scientific discipline and clinical decision making are huge, and specifically, healthcare organizations will need to adapt to new knowledge and technologies.

PS. Neuroepigenetics: DNA methylation and memory