Scientists accurately predict age with saliva sample

June 22, 2011

Self-conscious about your age? Careful where you spit. UCLA geneticists now can use saliva to reveal how old you are.

The June 22 advance online edition of the Public Library of Science (PLoS) ONE publishes the findings, which offer a myriad of potential applications. A newly patented test based on the research, for example, could offer crime-scene investigators a new forensic tool for pinpointing a suspect's .

"Our approach supplies one answer to the enduring quest for reliable markers of aging," said principal investigator Dr. Eric Vilain, a professor of , pediatrics and urology at the David Geffen School of Medicine at UCLA. "With just a saliva sample, we can accurately predict a person's age without knowing anything else about them."

Vilain and his colleagues looked at a process called methylation – a chemical modification of one of the four building blocks that make up our DNA.

"While genes partly shape how our body ages, environmental influences also can change our DNA as we age," explained Vilain. "Methylation patterns shift as we grow older and contribute to aging-related disease."

Using saliva samples contributed by 34 pairs of identical male twins ages 21 to 55, UCLA researchers scoured the men's genomes and identified 88 sites on the DNA that strongly correlated methylation to age. They replicated their findings in a general population of 31 men and 29 women aged 18 to 70.

Next, the scientists built a predictive model using two of the three genes with the strongest age-related linkage to methylation. When they plugged in the data from the twins' and the other group's saliva samples, they were able to correctly predict a person's age within five years – an unprecedented level of accuracy.

"Methylation's relationship with age is so strong that we can identify how old someone is by examining just two of the 3 billion building blocks that make up our genome," said first author Sven Bocklandt, a former UCLA geneticist now at Bioline.

Vilain and his team envision the test becoming a forensic tool in crime-scene investigations. By analyzing the traces of left in a tooth bite or on a coffee cup, lab experts could narrow the age of a criminal suspect to a five-year range.

In a minority of the population, methylation does not correlate with chronological age. Using this data, scientists may one day be able to calculate a person's "bio-age" -- the measurement of a person's biological age versus their chronological age.

Physicians could evaluate the risk of age-related diseases in routine medical screenings and tailor interventions based on the patient's bio-age rather than their chronological age. Instead of requiring everyone to undergo a colonoscopy at age 50, for example, physicians would recommend preventive tests according to a person's bio-age.

"Doctors could predict your medical risk for a particular disease and customize treatment based on your DNA's true biological age, as opposed to how old you are," noted Vilain. "By eliminating costly and unnecessary tests, we could target those patients who really need them."

The UCLA team is currently exploring whether people with lower bio-age live longer and suffer less disease. They also are examining if the reverse is true -- whether higher bio-age is linked to a greater rate of disease and early death.

Related Stories

Recommended for you

Association found between abnormal cerebral connectivity and variability in the PPARG gene in developing preterm infants

December 12, 2017
(Medical Xpress)—A team of researchers with King's College London and the National Institute for Health Research Biomedical Research Centre, both in the U.K., has found what they describe as a strong association between ...

Large genetic study links tendency to undervalue future rewards with ADHD, obesity

December 11, 2017
Researchers at University of California San Diego School of Medicine have found a genetic signature for delay discounting—the tendency to undervalue future rewards—that overlaps with attention-deficit/hyperactivity disorder ...

Gene variants identified that may influence sexual orientation in men and boys

December 8, 2017
(Medical Xpress)—A large team of researchers from several institutions in the U.S. and one each from Australia and the U.K. has found two gene variants that appear to be more prevalent in gay men than straight men, adding ...

Disease caused by reduction of most abundant cellular protein identified

December 8, 2017
An international team of scientists and doctors has identified a new disease that results in low levels of a common protein found inside our cells.

Study finds genetic mutation causes 'vicious cycle' in most common form of amyotrophic lateral sclerosis

December 8, 2017
University of Michigan-led research brings scientists one step closer to understanding the development of neurodegenerative disorders such as ALS.

Mutations in neurons accumulate as we age: The process may explain normal cognitive decline and neurodegeneration

December 7, 2017
Scientists have wondered whether somatic (non-inherited) mutations play a role in aging and brain degeneration, but until recently there was no good technology to test this idea. A study published online today in Science, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.