By Jeremiah Dobruck
9:54 PM PST, January 3, 2013
A UC Irvine researcher has helped uncover a link between a certain genetic variation and longer life.
People who live past 90 are significantly more likely to have a dopamine-receptor gene variation named the DRD4 7R allele, according to a UCI and Brookhaven National Laboratory study, the campus announced Thursday.
By analyzing genetic samples from 310 people older than 90 and thousands of members of a control group younger than 46, UCI professor Robert Moyzis found there was a 66% increase of the allele, or alternative form of the gene, in the seniors.
People with this gene variation are more motivated to pursue social, intellectual and physical activities, Moyzis said, and because the variation encourages more activity, it indirectly produces longer life.
"While the genetic variant may not directly influence longevity, it is associated with personality traits that have been shown to be important for living a longer, healthier life," he said in a prepared statement. "It's been well documented that the more you're involved with social and physical activities, the more likely you'll live longer. It could be as simple as that."
But that's not the whole story of DRD4 7R. While simultaneously correlated with longevity, the variant is also linked to potentially risky or addictive behaviors and hyperactivity disorders like ADD or ADHD, according to the study.
That duplicity isn't uncommon though, Moyzis said: "There's probably few genes or gene variants that are just good or bad. It's probably context-dependent."
An 8-year-old squirming in class because he's bored by the subject may be unwanted behavior, but a highly motivated, multi-tasking entrepreneur is exhibiting similar — but acceptable — behavior, the professor said.
In fact, a desire to roam and explore associated with DRD4 7R may be responsible for humanity's spread across Earth.
UCI psychology and social behavior professor Chuansheng Chen believes this gene variation was evolutionarily selected more than 30,000 years ago during the out-of-Africa human exodus.
"It's pretty easy to speculate that this kind of personality trait to explore new areas must have been a critical thing. Otherwise why would you walk all the way across the planet?" Moyzis said.
In fact, he added, the gene is becoming even more prevalent.
Moyzis, who studies biological chemistry, partnered with Dr. Nora Volkow, a researcher at the Brookhaven National Laboratory, on this project.
She backed up his results when she found the lifespan of mice with the gene variation increased 7% to 9.7% compared to mice without it.
Moyzis said it's clear the allele can contribute to longer life but said further study is needed to see if it has clinical use.
The group of seniors he studied are mostly deceased, but their cell lines have been recorded and immortalized, Moyzis said.
Those lines will be key for further research and determining if there is clinical application to the study's findings.
"Even though these people are deceased, their cells will live forever," Moyzis said.