A gene associated with cell shape provides insights into the phenomenon of left-handedness

Lady Gaga, Barack Obama, Bill Gates, Paul McCartney, and Justin Bieber all share something in common with Jimi Hendrix, Judy Garland, and David Bowie – they are left-handed, a trait found in about 10% of the population. However, the reasons behind left-handedness in some individuals remain a topic of ongoing research, and a recent study has shed light on a genetic factor contributing to left-handedness.

Researchers have identified rare variants of a gene known as TUBB4B, which is involved in regulating cell shape. These variants were found to be 2.7 times more prevalent in left-handed individuals. Although these genetic variations account for only a small fraction of left-handedness, approximately 0.1%, the study suggests that the TUBB4B gene may play a role in the development of brain asymmetry, which is fundamental to determining hand dominance.

In most people, the two hemispheres of the brain exhibit slight anatomical differences and are dominant for different functions. For example, the left hemisphere typically controls language, while the right hemisphere is responsible for tasks involving spatial attention. In right-handed individuals, the left hemisphere usually governs the dominant right hand. However, in left-handers, the right hemisphere takes control of the dominant hand, leading to questions about what drives this brain asymmetry variation.

TUBB4B regulates a protein integrated into microtubules, which provide structural support within cells. The discovery of rare mutations in this gene more common in left-handed individuals suggests that microtubules may contribute to establishing the brain’s asymmetry during development. The findings, based on genetic data from over 350,000 adults in the UK Biobank, highlight the potential role of genetic factors in determining hand dominance.

While left-handedness is often considered a result of random variation during brain development, historical and cultural factors have also influenced its prevalence. Over time, many societies have stigmatized left-handedness, attempting to coerce left-handed individuals into adopting right-handedness. This cultural bias is reflected in language, with terms like “sinister” originating from Latin words for “left side.”

Moreover, the prevalence of left-handedness varies globally, with lower rates in certain regions due to cultural norms that suppress left-handedness. Interestingly, left-handedness has been associated with certain psychiatric conditions like schizophrenia and autism, suggesting a potential link between brain asymmetry and psychiatric traits.

Overall, the study underscores the complex interplay between genetics, brain development, and cultural influences in shaping hand dominance and highlights the relevance of understanding these factors in both neuroscience and psychiatry.