Tiny gene change affects brain size, IQ

2012-04-16 07:44
Paris - An international team of scientists said on Sunday the largest brain study of its kind had found a gene linked to intelligence, a small piece in the puzzle as to why some people are smarter than others.

A variant of this gene "can tilt the scales in favour of a higher intelligence", study leader Paul Thompson told AFP, stressing though that genetic blessings were not the only factor in brainpower.

Searching for a genetic explanation for brain disease, the scientists stumbled upon a minute variant in a gene called HMGA2 among people who had larger brains and scored higher on standardised IQ tests.

Thompson dubbed it "an intelligence gene" and said it was likely that many more such genes were yet to be discovered.

The variant occurs on HMGA2 where there is just a single change in the permutation of the four "letters" of the genetic code.

DNA, the blueprint for life, comprises four basic chemicals called A (for adenine), C (cytosine), T (thymine) and G (guanine), strung together in different combinations along a double helix.

In this case, the researchers found that people with a double "C" and no "T" in a specific section of the HMGA2 gene had bigger brains on average.

"It is a strange result, you wouldn't think that something as simple as one small change in the genetic code could explain differences in intelligence worldwide," said Thompson, a neurologist at the University of California at Los Angeles.

Study of brain scans

The discovery came in a study of brain scans and DNA samples from more than 20 000 people from North America, Europe and Australia, of European ancestry.

People who received two Cs from their parents, a quarter of the population, scored on average 1.3 points higher than the next group -half of the population with only one C in this section of the gene.

The last quarter of people, with no Cs, scored another 1.3 points lower.

"The effect is small," said Thompson, but "would be noticeable on a [IQ] test ... [it] may mean you get a couple more questions correct.

"It wouldn't be an enormous change. Even so, it would help our brain resist cognitive decline later in life."

It is generally accepted that genes, a good education and environmental factors combine to determine our intelligence.

"If people wanted to change their genetic destiny they could either increase their exercise or improve their diet and education," said Thompson. "Most other ways we know of improving brain function more than outweigh this gene."

He added there were ethical safeguards and laws in place to guard against the abuse of genetic information.

The research, published in Nature Genetics, was conducted by more than 200 scientists from 100 institutions worldwide, working together on a project called Enigma.

Thompson said other studies have implicated some genes in IQ, but this was the first to link a common gene to brain size.

Small genetic changes

The team found that every T in place of a C represented a 0.6% smaller brain - equal to more than a year's worth of brain loss through the normal ageing process.

Asked to comment on the research, Tom Hartley, a psychologist at Britain's University of York said he was "a little wary of thinking in terms of a gene for intelligence.

"There are undoubtedly a lot of things that have to work properly in order to get a good score on an IQ test, if any of these go wrong the score will be worse".

But he said it was "fascinating" to find that such small genetic changes could affect the size of critical structures such as the hippocampus, the brain's memory centre.

"Given the importance of the hippocampus in disorders such as Alzheimer's disease these could turn out to be very significant findings," said Hartley.

John Williams, head of neuroscience and mental health at the Wellcome Trust, a British charitable foundation which backs biomedical research, said the findings paved the way for further research into "structural changes" which occur in disorders such as dementia, autism and schizophrenia.

- SAPA
Read more on:    science
NEXT ON NEWS24X
SHARE:

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
6 comments
Add your comment
Comment 0 characters remaining
 

Inside News24

 
/Travel
 

LOL treadmill fail!

Watch this hilarious clip! We think this man should rather be running outside this summer!

 
 

I love summer.24

Google’s top searches of 2014
10 of the strangest Christmas traditions around the world
2014's best drone videos
7 drinks you need to make this party season

Jobs in Cape Town [change area]

Property [change area]

Travel - Look, Book, Go!

Kalahari.com - shop online today

Up to 50% off on outdoor gear

Save on chairs, blankets, cooler bags, umbrellas and more. Shop now!

Save on Samsung

Cameras, mobile phones, TVs, Tablets and more. While stocks last. Shop now!

15% off LEGO

Save 15% when you buy 2 or more Lego toys. Offer valid while stocks last. Shop now!

Grand Theft Auto 5

Now available on PS4, Xbox One and PC from R649. Buy now!

Festive gifts!

Check out our awesome range of festive gifts to make everyone’s wishes come true. Shop now!

OLX Free Classifieds [change area]

Samsung Galaxy s4

Mobile, Cell Phones in South Africa, Western Cape, Cape Town. Date October 24

Best bargain in big bay

Real Estate, Houses - Apartments for Sale in South Africa, Western Cape, Cape Town. Date October 25

VW Golf 6, 1.6 Trendline (Excellent condition)

Vehicles, Cars in South Africa, Western Cape, Cape Town. Date October 25

Horoscopes
Aquarius
Aquarius

Any chance to explore the distant shores of things yet to be found will fascinate you. The challenge is dealing with the issues...read more

There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.








Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.