In a recently patented research, UCLA geneticists have shown and demonstrated how they’ve accurately been able to predict a person’s age just by analyzing a saliva sample. The research could possibly find highly welcomed applications in crime scene investigation, as a forensics tool for pinpointing a suspect’s age.

“Our approach supplies one answer to the enduring quest for reliable markers of aging,” said principal investigator Dr. Eric Vilain, a professor of human genetics, 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.”

To achieve this, scientists used 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,” Vilain said. “Methylation patterns shift as we grow older and contribute to aging-related disease.”

In the first round of testing, researchers sampled saliva from 34 pairs of identical male twins, aged between 21 and 55, whose genome was then analyzed. Scientists identified 88 sites on the DNA that strongly correlated methylation to age. In the second round, they replicated their findings after extending to a general population of 31 men and 29 women between the ages of 18 and 70.

Using two of the three genes with the strongest age-related linkage to methylation, scientists constructed a predictive model which helped them tell the age of a study participant within a range of 5 years, an incredible approximation by today’s standard.

“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.

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In some people, methylation does not correlate with chronological age. This is because a person’s age is measured in both chronological age and bio-age, which is the true age of a subject. Using data from this particular reserach, scientists might be able to lay the forefront for future accurate bio-age measurements. Medical applications would be both numerous and highly advantageous.

“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,” Vilain said. “By eliminating costly and unnecessary tests, we could target those patients who really need them.”

The UCLA team is currently exploring whether people with a lower bio-age live longer and suffer less disease. They also are examining if the reverse is true — whether a higher bio-age is linked to a greater rate of disease and early death.
The findings can be read in more detail in the June 22 edition of PLoS One, an online journal of the Public Library of Science.

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