By Sun Zifa
In the latest issue of Nature Communications, a genetic study suggests that rare genetic variations that cause protein alterations and genes related to microtubules may be associated with the formation of individuals commonly known as "lefties." This discovery could advance our understanding of the genetic basis behind left and right-handed tendencies.
According to the paper, only about 10% of the population are left-handed, a phenomenon that occurs when the right hemisphere of the brain dominates control over the left hand (opposite for right-handed individuals). The asymmetry in brain dominance for the dominant hand appears early in life, indicating a possible genetic influence. Previous population studies have identified some common genetic variations associated with left-handedness. Some of these variations involve genes encoding microtubule proteins, which are part of the cell's skeleton, supporting its shape. However, it was previously unclear how these genes affect left and right-handed tendencies.
To further investigate the genetic basis of handedness, the lead author of the paper, Clyde Francks from the Max Planck Institute for Psycholinguistics in the Netherlands, collaborated with colleagues and conducted a genome-wide screening using data from over 350,000 individuals in the UK Biobank. They aimed to identify rare genetic variations that are associated with left and right-handedness. The analysis included 38,043 left-handed individuals and 313,271 right-handed individuals.
The researchers found that, at the population level, the heritability of left-handedness due to rare coding variations was low, at less than 1%. They also discovered that a gene encoding a microtubule protein called TUBB4B had a 2.7 times higher likelihood of containing rare coding variations in the left-handed population compared to the right-handed population.
In this study, the authors also explored to what extent genes previously associated with schizophrenia, Parkinson's disease, Alzheimer's disease, and autism are related to handedness. They suggest that two genes previously linked to autism (DSCAM and FOXP1) may also be associated with left-handedness, although causal relationships have yet to be determined.
