Aging clock based on nucleosome reorganisation derived from cell-free DNA.

Aging induces systematic changes in the distribution of nucleosomes, which affect gene expression programs. Here we reconstructed nucleosome maps based on cell-free DNA (cfDNA) extracted from blood plasma using four cohorts of people of different ages. We show that nucleosomes tend to be separated by larger genomic distances in older people, and age correlates with the nucleosome repeat length (NRL). Furthermore, we developed the first aging clock based on cfDNA nucleosomics. Machine learning based on cfDNA distance distributions allowed predicting person's age with the median absolute error of 3-3.5 years.