According to a study conducted at the Max Planck Institute for Psycholinguistics, in The Netherlands, a genetic variant might be partially responsible for left-handedness.
The researchers found that rare variants of a gene coding for a tubulin protein, which gives shape to the cells, were commonly found 2.7 times more in left-handed people.
The study published in the journal Nature Communications, analyzed the genetic data of 313,271 right-handed people and 38,043 left-handed middle-aged people to understand the difference between the two.
“For example, most people have left-hemisphere dominance for language, and right-hemisphere dominance for tasks that require directing visual attention to a location in space,” said neurobiologist Clyde Francks, senior author of the study. “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 is in control of the dominant hand. The question is: what causes the asymmetry of the brain to develop differently in left-handers?”
The findings revealed that a gene, called TUBB4B, might play an important role in the development of brain symmetry by controlling microtubules which determine the dominant hand.
“We think that most instances of left-handedness occur simply due to random variation during the development of the embryonic brain, without specific genetic or environmental influences. For example, random fluctuations in the concentrations of certain molecules during key stages of brain formation,” Francks commented citing that the researchers are still unsure about the effect of microtubules on left-handedness.
The recent study also sheds light on the link between left-handedness and psychiatry as people suffering from schizophrenia are around twice as likely, and people with autism are around thrice as likely to be left-handed or ambidextrous.
“Some of the genes that function in the developing brain during early life might be involved in both brain asymmetry and psychiatric traits. Our study found suggestive evidence of this, and we have also seen it in previous studies where we looked at more common genetic variants in the population,” Francks explained.
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