A rare genetic variant is thought to play a role in understanding why people are left-hand dominant.| Trending Viral hub

What do Lady Gaga, Barack Obama, Bill Gates, Paul McCartney and Justin Bieber have in common with Ronald Reagan, Jimi Hendrix, Judy Garland, Fidel Castro and David Bowie? They are all left-handed, a trait shared by about 10% of people.

But why are some people left-handed and most right-handed? That is an area of active research, and a new study sheds light on a genetic component of left-handedness in some people. The researchers identified rare variants of a gene involved in controlling cell shape and found that they were 2.7 times more common in left-handed people.

While these genetic variants The study shows that this gene, called TUBB4B, may play a role in the development of brain asymmetry that underlies the determination of a dominant hand.


In most people, the two halves or hemispheres of the brain have slightly different anatomies and are dominant for different functions.

A gene involved in cell shape may explain left-handedness

There is a rare genetic variant involved in cell shape that is thought to be linked to left-handedness. (REUTERS/Carlos Jasso/File Photo)

“For example, most people are left-hemisphere dominant for language and right-hemisphere dominant for tasks that require directing visual attention to a location in space,” said neurobiologist Clyde Francks of the Max Planck Institute for Psycholinguistics in the Netherlands, lead author. of the study published Tuesday in the journal Nature Communications.

“In most people, the left hemisphere also controls the dominant right hand. The relevant nerve fibers cross from left to right in the lower part of the brain. In left-handers, the right hemisphere controls the dominant hand. The question is : What causes brain asymmetry to develop differently in left-handers?”

TUBB4B controls a protein that integrates into filaments called microtubules that provide the internal structure of cells. The identification of rare mutations in this gene that are more common in left-handers suggests that microtubules are involved in shaping the brain’s normal asymmetries, Francks said.

The two cerebral hemispheres begin to develop differently in the human embryo, although the mechanism remains unclear.

“Rare genetic variants in only a handful of people can identify genes that give clues to the developmental mechanisms of brain asymmetry in everyone. TUBB4B could be a good example of this,” Francks added.

The findings were based on genetic data covering more than 350,000 middle-aged and older adults in Britain in a data set called UK Biobank. About 11% were left-handed.


For most people, determining which hand is dominant can depend on chance.

“We believe that most cases of left-handedness occur simply due to random variation during embryonic brain development, without specific genetic or environmental influences. For example, random fluctuations in the concentrations of certain molecules during key stages of brain formation. brain,” Francks said. saying.

Over the centuries, many cultures looked down on left-handedness and tried to force left-handed people to become right-handed. In English, the word “correct” also means “correct” or “proper.” The word “sinister” derives from a Latin word meaning “on the left side.” And a “lefty compliment” means an insult disguised as praise.

The prevalence of left-handedness varies in different parts of the world, with lower rates in Africa, Asia and the Middle East compared to Europe and North America, Francks said.

“This probably reflects the suppression of left-handedness in some cultures, making left handed children to be right-handed, something that also happened in Europe and North America,” Francks added.


The new findings could have relevance in the field of psychiatry. While the overwhelming majority of left-handers have neither of these conditions, people with schizophrenia are about twice as likely to be left-handed or ambidextrous and people with autism are about three times as likely, Francks said.

“Some of the genes that function in the developing brain during early life could be involved in both brain asymmetry and psychiatric traits. Our study found suggestive evidence for this, and we have also seen it in previous studies in “We see more common genetic variants in the population,” Francks added.

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