TABLE 3.

Frequently mentioned potential “research lab” biomarkers based on epigenetic measurements.

Potential biomarkers	Material	Methods	Prediction	e-score	rc-score	c-score*
DNA methylation and aging clocks:					n.a.	2158
Horvath’s clock	DNA (broad spectrum of tissues)	DNA methylation analysis	Chronological age	–	n.a.	214
Hannum’s clock	DNA (blood)		Chronological age	–	n.a.	190
DNAm GrimAge	DNA (blood)		Biological age	–	n.a.	31
DNAm PhenoAge	DNA (blood)		Biological age	–	n.a.	26
Weidner clock	DNA (blood)		Chronological age	–	n.a.	8
EpiTOC	DNA (blood)		Biological age	—	n.a.	2
miRNA (microRNA)	RNA (blood/plasma PBMCs)	Next generation sequencing microarrays	Morbidity, mortality	—	198	635
Non-coding RNA expression profiles	RNA	RNA sequencing	Chronological age	—	167	602
exRNA (extracellular RNA)	blood/plasma	Next generation sequencing	Morbidity, mortality	—	25	119
Histone modifications:					36	73
H4K20 methylation		DNA methylation analysis mass spectrometry, HPLC, ChIP Immunohisto-chemistry	Cell stress	—	n.a.	n.a.
H4K16 acetylation				—	n.a.	n.a.
H3K4 methylation	protein extract			—	n.a.	n.a.
H3K9 methylation	from tissue DNA			—	n.a.	n.a.
H3K27 methylation				—	n.a.	n.a.
Chromatin remodeling	DNA	Chromatin remodeling assays	Chronological age	—	13	26

* rows are sorted by c-score. n.a.: not assigned due to high variation of terminology in literature.