The The prevalence of left-handedness is around 10% worldwide., although there are analyzes whose figures vary between 9.3 and 18.1%. This tendency to do so Preferably use your left hand or the foot on the same side is characterized by greater right hemisphere dominance.
Previous population studies found several common associated genetic variants. Some of these involve genes that code Microtubules which are part of the cytoskeleton, the framework that gives cells their shape. However, it is still unclear how these genes interfere with laterality, the spontaneous preference for using organs on the right or left side.
With the aim of thoroughly investigating the genetic basis of left-handedness, researchers at the Max Planck Institute for Psycholinguistics in the Netherlands analyzed genomic data from more than 350,000 people (38,043 left-handed and 313,271 right-handed) from the UK Biobank looking for rare genetic variants – with a frequency of less than 1% in the population – related.
The work was published today in Nature communicationsuggests that Left-handed people are 2.7 times more likely to have rare coding variants in the TUBB4B genealthough the heritability of left-handedness due to such rare coding mutations was low, less than 1%.
“We found that rare genetic variants in TUBB4B are associated with left-handedness. Although they only occur in fewer than 1 in 1,000 left-handed people, the finding is important because it links this gene to the development of cerebral asymmetry,” he explains to SINC. Clyde FranksLead author.
“The two hemispheres of the brain begin to develop differently in the human embryo, but the mechanism is unknown. Finding genes related to brain or behavioral asymmetries such as laterality could provide some clues,” he adds.
Left-right axis of the brain
Francks points out that rare exome variants contribute very little to the rate of left-handedness: “We have already suspected from other work that brain asymmetry varies mainly by chance in the early embryo.” Although for our purpose, low heritability was not a problem.”
“Although rare carriers of TUBB4B variants appear to be significantly more likely to be left-handed, we believe that most cases arise simply due to random variations during embryonic brain development, without specific genetic or environmental influences,” he emphasizes.
Although rare carriers of TUBB4B variants have an increased risk of being left-handed, most cases occur simply due to random variations during embryonic brain development.
The authors also examined the extent to which genes previously linked to schizophrenia, Parkinson’s, Alzheimer’s and autism were linked to laterality. They suggest that two genes previously linked to autism DSCAM and FOXP1may also be associated with left-handedness, but a causal relationship has not been proven.
In fact, the new results are not yet ready to be applied beyond basic research. “They contribute to a broader effort in psychiatry to understand the mechanisms of brain variation and how they can influence predisposition to brain diseases,” says Francks.
Reference:
Dick Schijven et al.: “Exome-wide analysis implicates rare protein-altering variants in human handedness.” Nature communication