Type |
Epigenetic Clock |
Tissue Type |
Methodology Used |
Methylation Technology |
Strengths |
Limitations |
Single Tissue |
57 |
Single Tissue: Saliva |
Association Analysis |
Illumina 27K array |
First epigenetic clock |
Low accuracy (mean AE:5.2 years) |
|
67
|
Single Tissue: Whole Blood
|
Elastic Net with bootstrapping
|
Illumina 450K Array
|
Accurate in blood.
Extensively used
|
Limited age range of training samples: 19-101 years
|
|
93 |
Single Tissue:
Whole Blood |
Multivariate Linear Regression |
Pyrosequencing |
Consists
of only three CpG sites |
Low accuracy (mean AE:5.4
years) |
|
94 |
Single Tissue:
Breast Tissue |
Elastic Net Regression with cross-validation |
TruSeq
Methyl Capture EPIC library |
Improved accuracy in breast tissue |
TruSeq Methyl Capture not yet widely used |
Multi-Tissue |
71 |
Multi-Tissue: Epidermis, dermis, T-cells, cervical smear, monocytes |
Pearson Correlation |
Illumina 27K array |
First multi-tissue clock |
Relative low accuracy (mean AE:11 years) |
|
75
|
Multi-Tissue: 51 tissue and cell types
|
Elastic Net with ten-fold cross-validation
|
Illumina 27K array & Illumina 450K Array
|
Accurate across tissues; Extensively used
|
Mostly adult samples
Age of neonate samples set at “0”
|
|
68 |
Multi-Tissue
including blood |
Elastic Net with ten-fold cross-validation |
Illumina
450K & Illumina EPIC array |
Accurate (mean AE: 2.5 years) |
Not widely
used yet |
Pediatric Single Tissue |
69 |
Single Tissue:
Buccal Cells |
Elastic Net with cross-validation |
Illumina EPIC Array |
Pediatric-only clock |
Low accuracy in blood |
Gestational
Age
|
74
|
Cord Blood
|
Elastic Net Regression with cross-validation
|
Illumina 27K array & Illumina 450K Array
|
Median error :1.24 weeks
|
Gestational Age Only
|
|
95 |
Cord Blood |
Lasso Regression with cross-validation |
Illumina EPIC array |
Uses EPIC
array |
Gestational Age Only |