Tweaking of genetic material is what makes a person's face different from another's, Lawrence Berkeley National Laboratory researchers found.
Have you ever wondered why your face is unique to only you? Yes! There may be a few people who look similar to you but unless you have an identical twin, there's probably one in a million chances that you'll find someone looking exactly like you.
In a study conducted on mice, researchers from Lawrence Berkeley National Laboratory found thousands of small regions of DNA that influence the way facial features develop. The discovery also revealed that a little tweaking of genetic material can alter a person's face shape.
"Our results suggest it is likely there are thousands of enhancers in the human genome that are somehow involved in craniofacial development," said Axel Visel, a geneticist with Berkeley Lab's Genomics Division who led this study. "We don't know yet what all of these enhancers do, but we do know that they are out there and they are important for craniofacial development."
Though previous studies have identified genetic defects responsible for craniofacial pathologies such as clefts of the lip or palate, this is the first study to look deeply into the genetic drivers of normal craniofacial variation. In a previous study conducted by Visel and his colleagues, it was found that gene enhancers can regulate their targets from across distances of hundreds of thousands of base pairs. Visel and his team were curious to learn whether gene enhancers can also have the same long-distance impact on craniofacial development and, hence, conducted a study on transgenic mice.
They found that more than 4,000 candidate enhancer sequences were active in fine-tuning the expression of genes involved in craniofacial development. The researchers created genome-wide maps of these enhancers by pin-pointing their location in the mouse genome. They then characterized in detail the activity of some 200 of these gene enhancers and deleted three of them.
"Knowing about the existence of these enhancers, which are inherited from parents to their children just like genes, knowing their exact location in the human genome, and knowing their general activity pattern in craniofacial development should facilitate a better understanding of the connection between genetics and human craniofacial morphology," Visel said. "Our results also offer an opportunity for human geneticists to look for mutations specifically in enhancers that may play a role in birth defects, which in turn may help to develop better diagnostic and therapeutic approaches."
Researchers hope that their findings will help them get a better understanding of how facial birth defects arise. It may reveal why and how things can go wrong as embryos develop in the womb, leading to these facial defects.
"We're trying to find out how these instructions for building the human face are embedded in human DNA," Visel told BBC News. "Somewhere in there, there must be that blueprint that defines what our face looks like."
Visel clarifies that though they are just at the beginning of understanding what shapes a person's face, he can already foresee that it's a very complex process.
