You might think it’s rather obvious that your facial appearance is decided by your genes. Just look in the family photo album and observe the same nose, eyes or chin on your grandparents, cousins & uncles & aunts. Perhaps you’ve got seen or know someone with a genetic syndrome that often results from a damaging alteration to one or more genes & noticed the usually distinctive facial features.
You may be surprised to learn that until very recently, geneticists had virtually no understanding of which parts of our DNA were linked to the most basic aspects of facial appearance. This gap in our knowledge was particularly galling since facial appearance plays such a crucial role in basic human interactions. The availability of huge data sets combining genetic information with facial images which can be measured has rapidly advanced the pace of discovery.
So, what we really know about the genetics of facial appearance? Can we reliably predict a person face from their DNA? What are the implications for health & disease? We are an anthropologist & a human geneticist whose research focuses on uncovering the biological factors that underlie the similarities & differences in facial appearance among humans.
How Many Genes Are Related To Facial Appearance?
We still don’t have an entire answer to this question but recent work published in Nature Genetics by their collaborative research team identified more than 130 chromosomal regions related to specific aspects of facial shape. Identifying these regions is a critical initiative toward understanding how genetics impacts our faces & the way such knowledge could impact human health in the future.
Scientists accomplished this by scanning the DNA of more than 8000 individuals to look for statistical relationships between about 7 million genetic markers known locations in the genetic code where humans vary and dozens of shape measurements derived from 3D facial images.
When they find a statistical association between a facial feature & one or more genetic markers, this points us to a really very precise region of DNA on a chromosome. The genes located around the region then become our prime candidates for facial features like nose or lip shape, especially if they’ve other relevant information about their function, for instance, they’ll active when the face is forming in the embryo.
While more than 130 chromosomal regions could seem like a sizable amount, they are likely only scratching the surface. They expect that thousands of such regions and thus thousands of genes contribute to facial appearance. Many of the genes at these chromosomal regions have such small effects, they may never have enough statistical power to detect them.
What We Really Know About These Genes?
When they look collectively at the implicated genes at these 130+ DNA regions, some interesting patterns emerged.
Your nose is the part of your face most influenced by your genes. Perhaps not surprisingly, areas just like the cheeks, which are highly influenced by lifestyle factors like diet, showed the few genetic associations.
The ways in which these genes influence facial shape wasn’t at all uniform. Some genes, they found had highly localized effects & impacted very specific parts of the face while others had broad effects involving multiple parts.
They found that a huge proportion of these genes are involved in basic developmental processes that build our bodies, bone formation, for instance. And in many cases, they are the same genes that are implicated in rare syndromes & facial anomalies like birth defect.
They found it interesting that there was a high degree of overlap between the genes involved in facial & limb development which can provide a crucial clue on why many genetic syndromes are characterized by both hand & facial malformations. In another curious twist, they found some evidence that the genes involved in facial shape can also be involved in cancer, an intriguing finding given emerging evidence that individuals treated for pediatric cancer show some distinctive facial features.
Can Someone Construct Accurate Picture Of Face By Taking DNA?
It is unlikely that today or for the foreseeable future, someone could take a sample of DNA & use it to construct a picture of that face. Predicting an individual’s facial appearance like any complex genetic trait is a very difficult task.
To put that statement in context, the 130+ genetic regions they identified explain but 10% of the variation in facial shape. However, they understood all of the genes involved in facial appearance, prediction still be a monstrous challenge. This is often because complex traits like facial shape aren’t determined by simply summation the effects of a bunch of individual genes. Facial features are influenced by many biological & non-biological factors: age, diet, climate, hormones, trauma, disease, sun exposure, biomechanical forces & surgery.
All of these factors interact with our genome in complex ways in which they’ve not even begun to understand. To add to this picture of complexity, genes interact with one another, this is often referred to as “epistasis” and its effects are often complex & unpredictable.
It isn’t surprising then, that researchers attempting to predict individual facial features from DNA are unsuccessful. This is often to not say that such prediction will never be possible but if someone is telling you they will do that today, you ought to be highly skeptical.
How Might Research Connecting Genes & Faces Benefit Humans?
One of the most exciting developments in medicine in the 21st century is that the use of patient’s genetic information to make personalized treatment plans with an ultimate goal of improving health outcomes.
A deeper understanding of how genes influence the timing & rate of facial growth might be not useful tool for planning treatments in fields like orthodontics or reconstructive surgery. For instance, if someday we will use genetics to predict, when a child’s jaw will hit its peak growth potential, orthodontists could also be able to use this information to help to determine the optimal time to intervene for maximal effect.
Likewise, knowledge of how genes work individually & together to determine the size & shape of facial features can provide new molecular targets for drug therapies aimed at correcting facial growth deficiencies.
Lastly, greater knowledge of the genes that build human faces may offer us new insights into the basic causes of congenital facial malformations which may profoundly impact quality of life for those affected and their families.
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