Telomere Core Services & Resources

Telomere Core Assays

The Telomere Research Core

The Blackburn Telomere Research Core was created in 2009 to meet the needs of researchers to examine the role of telomere maintenance in human aging, diseases, and risk factors. To date, the Core has provided telomere assays through recharge to over 100 research teams from 50 institutions (US and 7 other countries) that resulted in over 150 publications.

Selected publications featuring our assays, available upon request

Services

Consultation for study design, sample collection, processing and transportation
PBMC sample preparation
Protocols for sample collection, processing and transportation upon request
Telomere length measurement in human samples: venous blood, dry blood spots, saliva
Telomere length measurement in non-human primate (mouse, macaque, lemur, rat, cat)
Telomerase activity measurement from human PBMCs
Telomerase activity measurement in mouse (various tissues)
Mitochondrial DNA copy number assay (cellular and cell-free)
Genomic SNP analyses
Development and validation of new telomere function assays and other molecular assays

Protocols

Links to PDFs:

Blood Draw Protocol for TL

DNA Aliquoting and Shipping for qPCR TL

Dried Blood Spot Collection

Oragene Saliva Collection

PBMC Purification for TA and TL

Resources

New Telomere Investigator Handbook

The Telomere Research Network

The Stress Measurement Network

The Aging, Metabolism and Stress Center

Method Validation

Telomere length assay precision is critical for determining whether a study is statistically powered to detect associations with TL (Nettle et al, 2019; Lindrose et al. 2020).

In the recent years, intra-class correlation coefficient (ICC), as opposed to coefficient of variation (CV), is considered a valid metric for TL assay precision estimation (Verhulst et al., 2015; Eisenberg, 2016; Verhulst et al., 2016). According to the NIH funded Telomere Research Network’s guideline (https://trn.tulane.edu), ICC of repeat DNA extractions from the same source specimen captures the whole process of TL assay and should be use assess the TL assay precision for each lab. We provide examples of ICCs for whole blood, peripheral blood mononuclear cells (PBMCs), dried blood spots and saliva samples here to illustrate high precision of our lab’s TL assay.

Detailed instructions of how to calculate the ICC using R and an example data set can be found at the Telomere Research Network’s website (https://trn.tulane.edu/wp-content/uploads/sites/445/2020/10/How-to-calculate-repeatability.pdf)

Telomere Core ICC measurements

Study	Specimen	DNA Extration Kit	No. Samples	ICC	CI
1	Human PBMC	QIAamp DNA Blood Mini	36	0.955	[0.914, 0.977]
2	Human Dried Blood Spot	QIAamp DNA Investigator	74	0.786	[0.683, 0.860]
3	Human Whole Blood	QIAamp DNA Blood Mini	48	0.944	[0.903, 0.968]
4	Human Whole Blood	QIAamp DNA Blood Mini	101	0.851	[0.787, 0.896]
5	Human Whole Blood	QIAamp DNA Blood Mini	30	0.726	[0.428, 0.872]
6	Human Saliva	Agencourt DNAdvance	45	0.95	[0.911, 0.972]
7	Human Saliva	PrepIT.L2P	47	0.809	[0.678, 0.889]
8	Human Saliva	QIAamp DNA Blood Mini	47	0.937	[0.891, 0.965]

Eisenberg, D. T. (2016). Telomere length measurement validity: the coefficient of variation is invalid and cannot be used to compare quantitative polymerase chain reaction and Southern blot telomere length measurement techniques. International Journal of Epidemiology, 45(4), 1295-1298. doi:10.1093/ije/dyw191

Nettle, D., Seeker, L., Nussey, D., Froy, H., & Bateson, M. (2019). Consequences of measurement error in qPCR telomere data: A simulation study. PLoS ONE, 14(5), e0216118. doi:10.1371/journal.pone.0216118

Lindrose, A.R., McLester-Davis. L.W.Y., Tristano, R.I., Kataria, L., Gadalla, S.M., Eisenberg, D.T.A., Verhulst, S., & Drury, S. Method comparison studies of telomere length measurement using qPCR approaches: a critical appraisal of the literature. bioRxiv preprint doi: https://doi.org/10.1101/2020.09.04.282632.

Verhulst, S., Susser, E., Factor-Litvak, P. R., Simons, M., Benetos, A., Steenstrup, T., . . . Aviv, A. (2016). Response to: Reliability and validity of telomere length measurements. International Journal of Epidemiology, 45(4), 1298-1301. doi:10.1093/ije/dyw194 Verhulst, S., Susser, E., Factor-Litvak, P. R., Simons, M. J., Benetos, A., Steenstrup, T., Aviv, A. (2015). Commentary: The reliability of telomere length measurements. International Journal of Epidemiology, 44(5), 1683-1686. doi:10.1093/ije/dyv166

A Note on Current Telomere Length Terminology

TL, observed TL: The observed telomere length (often simply referred to as TL ); is the measured phenotypically observed telomere length as measured by various methods. Of note, the observed TL is the cumulative result of both genetic and non-genetic contributions.

Telomere length genetic inheritance: This includes non-telomere regions (genes and their control regions) determined by genetic variance as well as direct transmission of the telomere ends from the parental gametes to the zygote. Therefore telomere length inheritance is therefore only partially determined by gene variants ^{1, 2}.

gTL: Genome-wide complex trait analysis (GCTA) estimated that additive genetic variance, that is, the totality of single nucleotide polymorphisms (SNPs), contributed 28% of total phenotypic variance of TL³. Several dozen individual single nucleotide polymorphisms have been found to be associated with measured TL in large genome-wide association studies ^{4, 5.}It is believed that many SNPs with smaller effects are yet to be discovered. In this sense, genetically determined telomere length (gTL) of an individual cannot be accurately determined currently. Nevertheless, the sum score of top TL SNPs has been proved to be a powerful tool in Mendelian Randomization studies that illustrated the causal effect of telomere length in several diseases including both degenerative diseases and cancers ^{4, 6.}

DNAmTL: Recently, a DNA methylation estimator of TL (DNAmTL) based on 140 CpGs was reported to be more strongly associated with age than measured TL and a better predictor of certain diseases and conditions ⁷. The modest correlations between DNAmTL and TL measured by qPCR and Flow-FISH⁸ suggest that DNAmTL and TL may reflect different aspects of telomere biology and requires further investigation.