Comparing qPCR and DNA methylation-based measurements of telomere length in a high-risk pediatric cohort

Abstract

Various approaches exist to assess population differences in biological aging. Telomere length (TL) is one such measure, and is associated with disease, disability and early mortality. Yet, issues surrounding precision and reproducibility are a concern for TL measurement. An alternative method to estimate TL using DNA methylation (DNAmTL) was recently developed. Although DNAmTL has been characterized in adult and elderly cohorts, its utility in pediatric populations remains unknown. We examined the comparability of leukocyte TL measurements generated using qPCR (absolute TL; aTL) to those estimated using DNAmTL in a high-risk pediatric cohort (N = 269; age: 8-13 years, 83% investigated for maltreatment). aTL and DNAmTL measurements were correlated with one another (r = 0.20, p = 0.001), but exhibited poor measurement agreement and were significantly different in paired-sample t-tests (Cohen's d = 0.77, p < 0.001). Shorter DNAmTL was associated with older age (r = −0.25, p < 0.001), male sex (β = −0.27, p = 0.029), and White race (β = −0.74, p = 0.008). By contrast, aTL was less strongly associated with age (r = −0.13, p = 0.040), was longer in males (β = 0.31, p = 0.012), and was not associated with race (p = 0.820). These findings highlight strengths and limitations of high-throughput measures of TL; although DNAmTL replicated hypothesized associations, aTL measurements were positively skewed and did not replicate associations with external validity measures. These results also extend previous research in adults and suggest that DNAmTL is a sensitive TL measure for use in pediatric populations.

What is the biological significance of DNA methylation-based estimators of telomere length? An assessment using the paternal age at conception effect and measures of external validity

“…While our study finds that qPCR TL outperforms PCDNAmTL and DNAmTL in almost all measures of external validity (those linked to inherited TL and the more precise southern blot method), past studies have found that DNAmTL is more strongly associated with age, sex, and all-cause mortality than measured TL is (Lu et al, 2019;Hastings et al, 2022;Pearce et al, 2021). This suggests puzzling aspects to how to interpret PCDNAmTL and DNAmTL.…”

“…DNAmTL and PCDNAmTL are further abstractions from this using elastic net regression models to mine for combinations of methylation markings which predict mean TL. These new DNAm estimators of TL are intriguing, especially in that they are sometimes more predictive of factors associated with TL than measured TL itself (Lu et al, 2019;Hastings et al, 2022;Pearce et al, 2021). However, our results show that PCDNAmTL and DNAmTL do not reliably detect the well-established paternal age at conception effect and show lower measures of external validity than qPCR measured TL.…”

“…many different epigenetic clocks; Ryan, 2021), DNAmTL is an attractive alternative to the additional wetlaboratory work required to derive other TL measurements. Intriguingly, when compared to measured TL itself, this DNAmTL estimator better correlates with a variety of variables that are thought to be causally linked with TL (Lu et al, 2019;Hastings et al, 2022;Seki et al, 2023;Pearce et al, 2021). For example, DNAmTL more strongly correlates with age, sex, and allcause mortality than measured TL does with these same three variables (Lu et al, 2019;Hastings et al, 2022;Pearce et al, 2021).…”

“…Intriguingly, when compared to measured TL itself, this DNAmTL estimator better correlates with a variety of variables that are thought to be causally linked with TL (Lu et al, 2019;Hastings et al, 2022;Seki et al, 2023;Pearce et al, 2021). For example, DNAmTL more strongly correlates with age, sex, and allcause mortality than measured TL does with these same three variables (Lu et al, 2019;Hastings et al, 2022;Pearce et al, 2021). This raises the prospect that predicted DNAmTL might serve as a better estimator of the biology captured by TL than is actual measured TL.…”

Biological aging markers in blood and brain tissue indicate age acceleration in alcohol use disorder

“…In recent studies, DNAmTL has been shown to have predictive value for a variety of disease phenotypes, such as HIV (Breen et al, 2022) and schizophrenia (Segura et al, 2022). The results from our study contribute to a growing body of evidence showing that DNAmTL and TL show little agreement and seem to differ in their way of assessing this biological feature (Hastings et al, 2022;Jung et al, 2023;Pearce et al, 2021). It has to be noted that we observed heterogeneity between the cohorts in the meta-analysis.…”