Telomeres are repetitive DNA sequences (TTAGGG) that protect chromosome ends but gradually shorten with each cell division, eventually leading to cell aging or death, making them important biomarkers of aging and disease risk. While telomere length varies across the 23 chromosome pairs, most earlier studies only measured average length, limiting chromosome specific insights. In a new study, researchers used long-read whole genome sequencing data from the NIH All of Us program along with a computational tool called Telogator2 to analyze telomere length at the chromosomal level, enabling more detailed understanding of telomere variation across individual chromosomes.

This is the largest study to date using long read sequencing to analyze telomere length in over 2,500 human samples, according to Pierce. Long read sequencing (10,000–30,000 base pairs) allows precise mapping of telomeres to specific chromosome ends, unlike short read sequencing (150–300 base pairs), which lacks sufficient resolution. Using data from the diverse NIH All of Us program, researchers observed clear, consistent differences in telomere length across chromosome arms, with some ends being longer and others shorter. Since telomere shortening reduces cell division capacity and tissue regeneration, these variations may help explain links between aging, cardiovascular disease, and other age related conditions.

The study highlights that variation in telomere length across chromosome arms is important for understanding aging related health outcomes. Researchers observed that younger individuals generally have longer telomeres, with length decreasing as age increases. The findings suggest telomere length patterns are largely set early in life, with some people consistently having shorter or longer telomeres over time. Additionally, longer telomeres tend to shorten more rapidly with age, indicating a stronger age related decline in initially longer chromosome ends.

The study did not find strong associations between chromosome specific telomere length and diseases such as diabetes or cardiovascular disease, but researchers suggest larger datasets may reveal clearer links in future work. The team is also investigating epigenetic changes, particularly DNA methylation, using long-read sequencing to better understand aging processes. They aim to develop epigenetic aging clocks based on extensive methylation data across the genome. The study, funded by the NIH and involving collaborators from multiple institutions, analyzed telomere length in 2,573 participants from the All of Us program.
source: https://biologicalsciences.uchicago.edu/news/aging-affects-human-genome-differently-across-chromosomes