When looking at family photographs, it’s often quite apparent how facial features are shared across generations, suggesting that they are inherited through a person’s genes. Yet, little is known about how variations in specific regions of the genome influence facial characteristics like a how long someone’s nose is or how wide set eyes are.
Knowing how genes affect facial features could help people learn about what cellular mechanisms influence these characteristics during development, and importantly, provide insight into what goes wrong in craniofacial birth defects that result in abnormal facial features.
Dr. Mary Marazita, professor and vice chair of the Department of Oral Biology, and Dr. Seth Weinberg, associate professor of oral biology, both in the University of Pittsburgh’s School of Dental Medicine, are leading global efforts in this field, working to understand the cause of craniofacial birth defects and the genetic basis of variation in human facial features.
Weinberg heads the Facial Imaging and Morphometrics Lab in the Center for Craniofacial and Dental Genetics at Pitt, of which Marazita serves as the director. The center works with researchers throughout the United States, Europe, Central and South America, Asia, and Africa using sophisticated statistical and molecular genetic methods to study the genetic, behavioral and epidemiological factors that influence gene expression.
Weinberg and Dr. John Shaffer, an assistant professor of human genetics at Pitt’s School of Public Health, recently published the results of one of their ongoing efforts to identify locations on the genome that influence facial features in the journal PLoS Genetics.
In their study, the researchers used two sample data sets, each comprised of unrelated individuals who of European ancestry from the United States who self-reported as being white. The data from approximately 3,000 individuals included genetic information along with a set of 20 craniofacial measurements that are commonly used in clinical settings. The measurements were obtained using stereophotogrammetry, a well-established imaging method that produces a data-rich representation of the surface contours of the body.
The researchers then performed a genome-wide association study to identify which genetic variants could have a statistically significant association with specific facial characteristics.
The study found that measures of eye, nose and facial breath could be associated with genetic variants in certain regions of the genome. In several of these regions, genes known to contribute to facial development or implicated in birth defects where the face is affected were found.
“We found several genetic links to facial features that have not been described before, Weinberg said. “The presence of genes known to be involved in facial development is encouraging as it suggests we are on the right track to finding out what causes craniofacial abnormalities.”
However, the influence of these genetic variants on the function of genes needs to be determined, Weinberg noted. Additionally, because many genes affect facial development and each of them may may only have a small effect, much larger population sizes would be needed to successfully map out all the genes and determine their effects. He and his team also plan to expand their study to include individuals of other ethnic origins.
Weinberg is the featured author in this week’s PLOS Science Wednesday “Ask Me Anything” chat from 1 to 2 pm EST March 8 on redditscience. Starting at that time, Weinberg and his colleagues answer questions about their PLOS Genetics article on facial morphology on redditscience. The AMA is just typing questions, there is no audio/video involved. Participants in the AMA will need a reddit account. Sign up here.