Methylome Modifications Offer New Measure Of Our 'Biological' Age

Researchers at the University of California have been able to describe markers and a model that quantify how aging occurs at the level of genes and molecules. Identifying these markers have been challenging for researchers before because they have looked at the telomeres-the repeating nucleotide sequences that cap the ends of chromosomes and which shorten with age. However, they have found that other factors like stress can affect them. Kang Zang, MD,PhD, professor of ophthalmology and human genetics at the Shiley Eye Center and director of the Institute for Genomic Medicine, focussed on DNA methylation, a process in which a methyl group is added or removed from the cytosine molecule in DNA to promote or suppress gene activity and expression. Zang and her colleagues found that an individual's "methylome" - the entire set of human methylation markers and changes across a whole genome - predictably varies over time, providing a way to determine a person's actual biological age from just a blood sample. She stated that the methylome provides a measure of biological age - how quickly or slowly a person is experiencing the passage of time. That information has potentially huge medical import. "For example, you could serially profile patients to compare therapies, to see if a treatment is making people healthier and 'younger.' You could screen compounds to see if they retard the aging process at the tissue or cellular level." 

Trey Ideker, PhD, a professor of medicine and chief of the Division of Medical Genetics in the UC San Diego School of Medicine and professor of bioengineering in the Jacobs School of Engineering stated that cancer cells age differently than their surrounding normal cells. The findings, according to the study authors, have broad practical implications. Most immediately, they could be used in forensics to determine a person's age based only upon a blood or tissue sample.  He also stated that assessing an individual's methylome state could improve preventive medicine by identifying lifestyle changes that might slow molecular aging. He noted, however, that much more research remains to be done.