SEP 08, 2019 2:02 PM PDT

Left-handedness Linked to Genetic Regions, Brain Architecture

WRITTEN BY: Carmen Leitch

It’s known that genes influence handedness; studies of twins that share the same genes indicate that 25 percent of handedness variation is explained by genetic factors. But now scientists have looked in a much larger sample and for the first time, scientists have found a region of the genome that is linked to left-handedness. They have shown that these genetic regions are associated with brain architecture, and the connections that link parts of the brain that are involved in language. The findings, which utilized data from around 400,000 people in the UK Biobank, have been reported in the journal Brain.

Image credit: Pxhere

"Around 90 percent of people are right-handed, and this has been the case for at least 10,000 years. Many researchers have studied the biological basis of handedness, but using large datasets from UK Biobank has allowed us to shed considerably more light on the processes leading to left-handedness," said Dr. Akira Wiberg, a Medical Research Council fellow at the University of Oxford.

"We discovered that, in left-handed participants, the language areas of the left and right sides of the brain communicate with each other in a more coordinated way. This raises the intriguing possibility for future research that left-handers might have an advantage when it comes to performing verbal tasks, but it must be remembered that these differences were only seen as averages over very large numbers of people and not all left-handers will be similar."

This work included genetic data from 38,332 left-handers. The researchers found four regions that were linked to handedness, and three of them contain proteins that impact the development and structure of the brain. They specifically relate to microtubules, which are part of the scaffolding that forms a cell’s structure - the cellular cytoskeleton.

By assessing brain images from around 10,000 study participants, the scientists showed that the genetic impacts are connected to structural changes in the white matter tracts of the brain. These contain parts of the brain cytoskeleton, which connects regions involved in language.

"Many animals show left-right asymmetry in their development, such as snail shells coiling to the left or right, and this is driven by genes for cell scaffolding, what we call the cytoskeleton," said joint senior study author Professor Gwenaëlle Douaud of the Wellcome Centre for Integrative Neuroimaging at the University of Oxford.

"For the first time in humans, we have been able to establish that these handedness-associated cytoskeletal differences are actually visible in the brain. We know from other animals, such as snails and frogs, that these effects are caused by very early genetically-guided events, so this raises the tantalizing possibility that the hallmarks of the future development of handedness start appearing in the brain in the womb."

This work also found that left-handedness was linked to a very slight reduction in the risk of Parkinson’s disease, and a very slight increase in the risk of schizophrenia. The researchers cautioned that these observations would only correspond to very few actual people that have the disease - they do not show a causal link. They may help show how the conditions develop, or may be one of many different factors that work together.

"Throughout history, left-handedness has been considered unlucky, or even malicious. Indeed, this is reflected in the words for left and right in many languages. For example, in English "right" also means correct or proper; in French "gauche" means both left and clumsy," noted joint senior study author Professor Dominic Furniss of the Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Science at the University of Oxford.

"Here we have demonstrated that left-handedness is a consequence of the developmental biology of the brain, in part driven by the complex interplay of many genes. It is part of the rich tapestry of what makes us human."


Sources: Science Daily via UK Research and Innovation, Brain

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
AUG 03, 2020
Genetics & Genomics
Understanding How Disease Risk Begins in Development
AUG 03, 2020
Understanding How Disease Risk Begins in Development
Many common complex diseases are thought to be caused by an interplay of genetic and environmental factors.
SEP 02, 2020
Microbiology
A Common Bacterium Can Evolve in the Stomach
SEP 02, 2020
A Common Bacterium Can Evolve in the Stomach
Helicobacter pylori can be found in as much as fifty percent of the world's population.
SEP 04, 2020
Genetics & Genomics
Expanding Our View of How Gene Variants Affect Blood Cells
SEP 04, 2020
Expanding Our View of How Gene Variants Affect Blood Cells
Small changes in the sequences of some genes affect the characteristics of blood cells, and may contribute to an individ ...
SEP 18, 2020
Coronavirus
How Coronavirus Spread in the US and Europe
SEP 18, 2020
How Coronavirus Spread in the US and Europe
Researchers are beginning to examine how the world's response to the pandemic virus SARS-CoV-2 went wrong, and right ...
SEP 21, 2020
Genetics & Genomics
Replicating the Genome With a Twist
SEP 21, 2020
Replicating the Genome With a Twist
Cold Spring Harbor Laboratory scientists have used cryo-EM to learn more about how the human genome is replicated.
OCT 05, 2020
Genetics & Genomics
A Rare Form of Dementia is Discovered
OCT 05, 2020
A Rare Form of Dementia is Discovered
There are different types of dementia, a term for a loss of cognitive function, including Alzheimer's disease and Le ...
Loading Comments...