Genes linked to being right- or left-handed identified
- September 12, 2013
- University of Oxford
- A genetic study has identified a biological process that influences whether we are right-handed or left-handed. Scientists found correlations between handedness and a network of genes involved in establishing left-right asymmetry in developing embryos.
A genetic study has identified a biological process that influences whether we are right handed or left handed.
Scientists at the Universities of Oxford, St Andrews, Bristol and the Max Plank Institute in Nijmegen, the Netherlands, found correlations between handedness and a network of genes involved in establishing left-right asymmetry in developing embryos.
‘The genes are involved in the biological process through which an early embryo moves on from being a round ball of cells and becomes a growing organism with an established left and right side,’ explained first author William Brandler, a PhD student in the MRC Functional Genomics Unit at Oxford University.
The researchers suggest that the genes may also help establish left-right differences in the brain, which in turn influences handedness.
They report their findings in the open-access journal PLOS Genetics.
Humans are the only species to show such a strong bias in handedness, with around 90% of people being right-handed. The cause of this bias remains largely a mystery.
The researchers, led by Dr Silvia Paracchini at the University of St Andrews, were interested in understanding which genes might have an influence on handedness, in order to gain an insight into the causes and evolution of handedness.
The team carried out a genome-wide association study to identify any common gene variants that might correlate with which hand people prefer using.
The most strongly associated, statistically significant variant with handedness is located in the gene PCSK6, which is involved in the early establishment of left and right in the growing embryo.
The researchers then made full use of knowledge from previous studies of what PCSK6 and similar genes do in mice to reveal more about the biological processes involved.
Disrupting PCSK6 in mice causes ‘left-right asymmetry’ defects, such as abnormal positioning of organs in the body. They might have a heart and stomach on the right and their liver on the left, for example.
The researchers found that variants in other genes known to cause left-right defects when disrupted in mice were more likely to be associated with relative hand skill than you would expect by chance.
While the team has identified a role for genes involved in establishing left from right in embryo development, William Brandler cautioned that these results do not completely explain the variation in handedness seen among humans. He said: ‘As with all aspects of human behaviour, nature and nurture go hand-in-hand. The development of handedness derives from a mixture of genes, environment, and cultural pressure to conform to right-handedness.’
Materials provided by University of Oxford . Note: Content may be edited for style and length.
- William M. Brandler, Andrew P. Morris, David M. Evans, Thomas S. Scerri, John P. Kemp, Nicholas J. Timpson, Beate St Pourcain, George Davey Smith, Susan M. Ring, John Stein, Anthony P. Monaco, Joel B. Talcott, Simon E. Fisher, Caleb Webber, Silvia Paracchini. Common Variants in Left/Right Asymmetry Genes and Pathways Are Associated with Relative Hand Skill. PLoS Genetics, 2013; 9 (9): e1003751 DOI: 10.1371/journal.pgen.1003751
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Are you left-handed or right-handed? Oleksandra Mykhailutsa/Shutterstock
By Robin Andrews
20 Feb 2017, 16:49
Most of us are right-handed , but a fair few happen to be left-handed. Why is this? Is it just something we learn to have a preference for over time, or is it something to do with our neurological wiring from birth? Are left-handed people really more evil than the rest of us, or is that just crazy talk?
According to a brand new study in the journal eLife , however, it is definitively nothing to do with our brains or our neurological development. In a rather satisfying plot twist, it seems that your left- or right-handedness is actually ingrained in your biological workings from before you were born, but in the form of a particular hubbub of gene activity in the spine , not the brain.
“Our data suggest a spinal, not a cortical, beginning of hemispheric asymmetries,” the team announced in their paper.
A team of researchers from Germany, the Netherlands and South Africa – led by biophysicists at Ruhr University Bochum – have been carefully monitoring the gene expression taking place within the developing spinal cords of growing babies inside the womb, between the eighth and twelfth weeks of pregnancy.
It’s long been assumed that gene activity in the brain, depending on which hemisphere shows the most activity, defines whether or not someone is right- or left-handed. However, based on activity in these proto-spinal cords, it seems that there’s some asymmetry going on there that’s never before been detected.
This newly discovered activity is taking place long before the part of the brain responsible for movement – the motor cortex – is actually “wired up” to the spine. It appears to be centered on parts of the spine responsible for transmitting electrical impulses to the hands, arms, legs, and feet, and this asymmetry defines whether a person writes with their right or left hand.
The fate of your hands is decided around the eighth week of development in the womb. u3d/Shutterstock
Moreover, the team actually found out what was causing this symmetry. As it so happens, it’s not influenced by regular, inherited genetic mutations or traits, but by environmental factors – influences that are affecting the baby as it grows in the womb.
Although it’s not yet clear what these environmental/external factors could be, it is possible that they alter how enzymes operate around the developing baby, which in turn changes how their genes are able to express themselves. This, consequently, influences the asymmetry of gene activity present within the spine.
So there you have it! Still no word on whether left-handed people are more evil, though.
[H/T: Huffington Post ]
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