'Smart genes' account for 20% of intelligence: study

May 22, 2017
A depiction of the double helical structure of DNA. Its four coding units (A, T, C, G) are color-coded in pink, orange, purple and yellow. Credit: NHGRI

Scientists on Monday announced the discovery of 52 genes linked to human intelligence, 40 of which have been identified as such for the first time.

The findings also turned up a surprising connection between intelligence and autism that could one day help shed light on the condition's origins.

Taken together, the new batch of "smart genes" accounted for 20 percent of the discrepencies in IQ test results among tens of thousands of people examined, the researchers reported in the journal Nature Genetics.

"For the first time, we were able to detect a substantial amount of genetic effects in IQ," said Danielle Posthuma, a researcher at the Center for Neurogenomics and Cognitive Research in Amsterdam, and the main architect of the study.

"Our findings provide insight into the biological underpinnings of intelligence," she told AFP.

Most of the newly discovered gene variants linked to elevated IQ play a role in regulating cell development in the brain, especially neuron differentiation and the formation of neural information gateways called synapses.

An international team of 30 scientists combed through 13 earlier studies in which detailed genetic profiles and intelligence evaluations—based on IQ tests—had been compiled for 78,000 people, all of European descent.

Links with autism

Increasingly powerful computers have made it possible to scan and compare hundreds of thousands of genomes, matching tiny variations in DNA with diseases, body types or, in this case, native smarts.

The human genome has some 25,000 genes composed of more than three billion pairing of building-block molecules.

Many of the genetic variations linked with high IQ also correlated with other attributes: more years spent in school, bigger head size in infancy, tallness, and even success in kicking the tobacco habit.

One of the strongest—and most surprising—links was with autism, noted Posthuma.

"Gene variants associated with high IQ are also associated with higher risk of autism spectrum disorder," she said in an interview.

One gene in particular—SHANK3—"is a very good candidate for explaining that," she added.

Conversely, the absence of certain high-IQ genes was more common in people suffering from schizophrenia or obesity.

A genetic IQ test?

To challenge their own results, the researchers separately checked the 13 databases they drew from—each had used slightly different IQ tests—against the 52 gene variants to see if the combined match-up between intelligence and genetic profile held up. It did.

They also scanned a very large database that had not been part of their study. Once again, the link held up, though—as expected—with a smaller percentage overlap between with IQ.

Scientists would have to scan millions of genomes to find them all, and the raw data and computing power for doing so is still out of reach, Posthuma explained.

"For intelligence, there are thousands of genes," she said. "We have detected the 52 most important ones, but there will be a lot more."

Experts agree that genes probably account for up to half of measured intelligence. But even if scientists could map all the genetic quirks that contribute to being brainy, that might not be enough to predict IQ, much less success in life.

"We are looking at all these genetic effects in isolation," said Posthuma. "Maybe it's a certain pattern of genetic variants"—and not just their sheer number—"that makes you more intelligent."

The other major ingredient for achievement, she added, is exercising one's quotient of grey matter, however big or small it might be.

If someone with a big genetic endowment "chooses not to put any effort into learning, then that will definitely diminish their chances for achievement," Posthuma said.

Explore further: Intelligence is in the genes, but where?

More information: Suzanne Sniekers et al, Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence, Nature Genetics (2017). DOI: 10.1038/ng.3869

Related Stories

Intelligence is in the genes, but where?

October 2, 2012
(Medical Xpress)—You can thank your parents for your smarts—or at least some of them. Psychologists have long known that intelligence, like most other traits, is partly genetic. But a new study led by psychological scientist ...

Well-established views on heritable intelligence brought down: Genes and environment play dynamic role together

October 24, 2013
The well-established view that intelligence is largely genetically fixed and hardly malleable has been discarded. A team of Dutch research methodologists at VU University Amsterdam, the University of Amsterdam and Tilburg ...

Chimpanzee intelligence determined by genes

July 10, 2014
A chimpanzee's intelligence is largely determined by its genes, while environmental factors may be less important than scientists previously thought, according to a Georgia State University research study.

In the genes, but which ones? Earlier studies that linked specific genes to intelligence were largely wrong

February 24, 2012
For decades, scientists have understood that there is a genetic component to intelligence, but a new Harvard study has found both that most of the genes thought to be linked to the trait are probably not in fact related to ...

Intelligence 'networks' discovered in brain for the first time

December 21, 2015
Scientists from Imperial College London have identified for the first time two clusters of genes linked to human intelligence.

Genes are not destiny: Environment and education still matter when it comes to intelligence

August 22, 2016
Recent research has suggested that academic performance, reading ability and IQ have a genetic basis. This reinforces the popular notion that intelligence and related cognitive capacities are somehow "in our genes".

Recommended for you

Peers' genes may help friends stay in school, new study finds

January 18, 2018
While there's scientific evidence to suggest that your genes have something to do with how far you'll go in school, new research by a team from Stanford and elsewhere says the DNA of your classmates also plays a role.

Two new breast cancer genes emerge from Lynch syndrome gene study

January 18, 2018
Researchers at Columbia University Irving Medical Center and NewYork-Presbyterian have identified two new breast cancer genes. Having one of the genes—MSH6 and PMS2—approximately doubles a woman's risk of developing breast ...

Can mice really mirror humans when it comes to cancer?

January 18, 2018
A new Michigan State University study is helping to answer a pressing question among scientists of just how close mice are to people when it comes to researching cancer.

A centuries-old math equation used to solve a modern-day genetics challenge

January 18, 2018
Researchers developed a new mathematical tool to validate and improve methods used by medical professionals to interpret results from clinical genetic tests. The work was published this month in Genetics in Medicine.

Epigenetics study helps focus search for autism risk factors

January 16, 2018
Scientists have long tried to pin down the causes of autism spectrum disorder. Recent studies have expanded the search for genetic links from identifying genes toward epigenetics, the study of factors that control gene expression ...

Group recreates DNA of man who died in 1827 despite having no body to work with

January 16, 2018
An international team of researchers led by a group with deCODE Genetics, a biopharmaceutical company in Iceland, has partly recreated the DNA of a man who died in 1827, despite having no body to take tissue samples from. ...

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.