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The study identifies the areas of DNA that are also connected with the architecture of the brain. “About 90% of people are right-handed and have been for at least 10,000 years. Using large data sets from the British Biobank has allowed us to shed light on the processes that lead to the use of the left hand”.

Left-handed for “fault” of the genes. A new study identified for the first time the regions of the genome associated with the use of the left hand, linking their effects to the architecture of the brain. The study, published in Brain and conducted by researchers at the University of Oxford funded by the Medical Research Council, sheds new light on the genetics of left-handed people – including genes such as Leonardo or Einstein – also linking these DNA characteristics with the connections between the areas of the brain related, in particular, to language.

It was already known that DNA has a role in determining the dominant hand – studies on twins have estimated that 25% of the variation between right and left-handed people can be attributed to genes – but the ‘pieces’ of the DNA responsible were not known. The new study identified some of the genetic variants associated with the predominance of the left hand, analyzing the genomes of about 400,000 people in the British Biobank, including 38,332 left-handed people.

Of the four genetic regions identified, three were associated with specific proteins involved in brain development and structure. In particular, these proteins were related to microtubules, which are part of the cytoskeleton that drives the construction and functioning of cells in the body.

Furthermore, using detailed brain imaging of about 10,000 subjects, the researchers found that these genetic effects were associated with differences in the structure of the brain that joins the language-related regions. “About 90% of people are right-handed and have been for at least 10,000 years – comments Akira Wiberg of the University of Oxford – The use of large data sets by the British Biobank has allowed us to shed light on the processes that lead to the use of the left hand “.

“We have discovered – he continues – that in left-handed participants, the linguistic areas of the left and right sides of the brain communicate with each other in a more coordinated way. This suggests that left-handed people could have an advantage when it comes to performing verbal tasks, but we must remember that these differences were seen only at the level of averages on a very large number of people and that not all left-handed people will be similar “.

The researchers also highlighted correlations between the genetic regions involved in being left-handed and a slightly lower probability of having Parkinson’s disease, but also a slightly higher probability of schizophrenia. The study of genetic links could help improve understanding of the development of these serious diseases, the researchers explain. “Throughout history, the left-handed has been considered unlucky or even dangerous – concludes Dominic Furniss, senior author of the study – this is also reflected in the nuances related to the words right and left in many languages.

We have shown that being left-handed is a consequence of the developmental biology of the brain, partly guided by the complex interaction of many genes. It is part of the rich tapestry of what makes us human “.

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