In a genome-wide association study involving 19,644 individuals of European ancestry, an international team of researchers identified 472 genomic regions, or loci, that influence brain shape, of which 76 are also linked to face shape; these loci don’t influence cognitive ability, further debunking beliefs that intelligence can be assessed by facial features.
Naqvi et al. recently developed a data-driven approach to phenotyping complex, multidimensional traits; this multivariate approach, when applied to facial surface images, revealed numerous genomic loci with no previously known role in human face shape variation; in the new study, the team implemented this approach to discover associations between common genetic variants and brain shape, using MRI data from middle-aged participants in the UK Biobank. Image credit: Gerd Altmann.
“To study genetic underpinnings of brain shape, we applied a methodology that we had already used in the past to identify genes that determine the shape of our face,” said Professor Peter Claes, a researcher in the Laboratory for Imaging Genetics at KU Leuven.
“In these previous studies, we analyzed 3D images of faces and linked several data points on these faces to genetic information to find correlations.”
“This way, we were able to identify various genes that shape our face.”
In the current study, the scientists used information stored in the UK Biobank to study the brain structure — obtained through magnetic resonance imaging (MRI) — of 19,644 healthy people.
“To be able to analyze the MRI scans, we had to measure the brains shown on the scans,” Professor Claes said.
“Our specific focus was on variations in the folded external surface of the brain — the typical ‘walnut shape’.”
“We then went on to link the data from the image analyses to the available genetic information.”
The authors found 472 loci in the genome that affect brain shape. Of these, 76 were previously shown to influence facial structure.
“This way, we identified 472 genomic regions that have an impact on the shape of our brain. 351 of these locations have never been reported before,” he said.
“To our surprise, we found that as many as 76 genomic locations predictive of the brain shape had previously already been found to be linked to the face shape. This makes the genetic link between face and brain shape a convincing one.”
They also found evidence that genetic signals that influence both brain and face shape are enriched in the regions of the genome that regulate gene activity during embryogenesis, either in facial progenitor cells or in the developing brain.
“This makes sense as the development of the brain and the face is coordinated,” said Professor Joanna Wysocka, a researcher at the Stanford University School of Medicine.
“But we did not expect that this developmental cross-talk would be so genetically complex and would have such a broad impact on human variation.”
In the study, the team also briefly addressed conditions such as Alzheimer’s disease, schizophrenia, and bipolar disorder.
“As a starting point, we used the results that were previously published by other teams about the genetic basis of such neuropsychiatric disorders,” Professor Claes said.
“The possible link with the genes that determine the shape of our face had never been examined before.”
“If you compare existing findings with our new ones, you see a relatively large overlap between the genetic variants that contribute to specific neuropsychiatric disorders and those that play a role in the shape of our brain, but not for those that contribute to our face.”
“In other words: our risk of developing a neuropsychiatric disorder is not written on our face either.”
“We were astonished to find 76 genetic regions that affect both face and brain shape in the human population,” Professor Wysocka added.
“That’s an amazing degree of overlap, and it shows how closely these two structures affect each other during development. However, nothing in our data suggests that it’s possible to predict behavior, cognitive function or neuropsychiatric disorders like schizophrenia or ADHD simply by looking at a person’s face.”
The results appear in the journal Nature Genetics.
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S. Naqvi et al. Shared heritability of human face and brain shape. Nat Genet, published online April 5, 2021; doi: 10.1038/s41588-021-00827-w
Source link: https://www.sci.news/genetics/brain-face-shape-genetic-link-09525.html
