Pediatric Epigenetic Clock
As the field of epigenetic aging has broadened to study the effects of
childhood exposures on aging, pediatric epigenetic clocks have been
developed. The most prominent childhood clock is the
Pediatric-Buccal-Epigenetic
clock69 (PedBE) - a
94-CpG buccal epithelial cell clock developed using exclusively
pediatric samples (n=1,032, age range: 0.17-19.47 years) and elastic net
regression. PedBE’s performance was evaluated in an independent set of
689 buccal samples (age range: 0.01-19.96
years)69 where it had
median AE=0.35 years and r=0.98, demonstrating greater accuracy for that
age group compared to the pan-tissue Horvath
clock69. However, when
applied to an independent set of blood samples (n=134), the PedBE clock
was not as accurate (median AE =3.26 years) as the Horvath pan-tissue
clock (median AE= 0.57
years)69. This
performance discrepancy (blood vs. buccal samples) was expected due to
the tissue and cell-type specificity of DNAm. DNAm patterns are highly
influenced by tissue types as well as by cell type proportions in whole
blood.