Comparison of DNA methylation clocks in Black South African men.

Aims: DNA methylation clocks are widely used to estimate biological age, although limited data are available on non-European ethnicities. This manuscript characterizes the behavior of five DNA methylation clocks in 120 older Black South African men. Methods: The age estimation accuracy of the Horvath, Hannum and skin and blood clocks and the relative age-related mortality risk and predicted time to death portrayed by the PhenoAge and GrimAge biomarkers are investigated, respectively. Results: The results confirm the tendency of DNA methylation clocks to underestimate the biological age of older individuals. GrimAge more accurately characterizes biological decline in this African cohort compared with PhenoAge owing to the unique inclusion of smoking-related damage in the GrimAge estimate. Conclusions: Each clock provides a different fraction of information regarding the aging body. It is essential to continue studying under-represented population groups to ensure methylation-derived indicators are robust and useful in all populations.