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NIJMEGEN, Netherlands — Are you left or right-handed? The answer may have a lot to do with your genes. Researchers in the Netherlands have discovered that tubulins — unique proteins that build the internal skeletons of cells — also influence which hand is dominant.
A team from the Max Planck Institute for Psycholinguistics examined rare genetic variants from the genomes of more than 350,000 people during their study. Specifically, they wanted to find clues proving that certain aspects of our DNA influence which hand we end up favoring for basic tasks — such as writing or picking up your morning coffee. This led to the discovery that tubulins play a role in determining left-right brain asymmetry.
During the embryonic stage of human development, study authors explain that the left and right sides of the brain get wired differently. These differences lead to people having specific preferences as they grow, such as which side they lean to when they hug, which side of their mouth they tend to chew on, and which hand holds a pen or pencil.
The team adds that the left hand is dominant for just 10 percent of the world population.
A previous study from 2020 found 48 common gene variants connected to left-handedness. Most were in the non-coding regions of the DNA. Researchers say these included sections which may control genes related to tubulins.
In this new study, Clyde Francks, a geneticist and neuroscientist at the Max Planck Institute, notes that tubulins are long, tube-like filaments that control the shapes and movements of cells. These microtubules appear to influence which hand is dominant because they form cilia — hair-like objects in the cell membrane that direct the flow of fluids during human development.
Francks’ team analyzed the genetic data from 313,271 right-handed and 38,043 left-handed individuals during this project. That analysis discovered variants in a tubulin gene, TUBB4B, that was 2.7 times more likely among left-handed individuals.
Despite only affecting a small number of the people in this study, rare genetic variants “can give clues to developmental mechanisms of brain asymmetry in everyone,” Francks says in a statement.
The researchers believe their new findings may pave the way for future work which determines how microtubules give an “asymmetric twist” to early brain development. The study is published in the journal Nature Communications.
