The Genetics of Facial Morphology

Abstract

Human facial morphology broadly encompasses several distinct facial structures that alone and together contain enormous variations which contribute to our physical identities as both individuals and members of families and populations. The human face comprises an assemblage of multifactorial complex traits, with clear genetic components and known environmental factors playing key roles in its development and maturation throughout life. Current understanding of the genes and pathways pertaining to normal facial development and morphology comes largely from research on craniofacial malformations in both humans and animal models. Recent advances in methodology for deriving accurate and precise facial traits have allowed for several large genomic studies that have provided new insights into the heritability and genes involved in normal facial variation. Continued research on the genetics of facial morphology will improve quantitative diagnosis, treatment and management of craniofacial syndromes, perhaps enabling us to one day model the human face from deoxyribonucleic acid (DNA). Key Concepts Understanding the genetics of normal human facial morphology and development provides insights relevant to the fields of both medicine and forensics. The known genes and signalling pathways that are involved in craniofacial development have mostly been identified through studies of craniofacial malformations and typically relate to the embryonic development of cranial neural crest cells. Quantifying normal human facial traits that are both accurate and precise is exceedingly important to understanding the genetic architecture of those traits. There exist numerous diverse quantitation methods for studying both the underlying facial skeleton and the overlying soft facial tissues. Overall, the human face is highly heritable. However, large differences in the study design and population attributes pertaining to age, ethnicity and environmental background have led to limited consistency in heritability estimates and genetic conclusions. Five genome‐wide association studies to date have identified largely non‐overlapping genome‐wide significant loci for normal facial morphology, with some of these located in or near genes previously implicated in rare craniofacial syndromes and/or facial development. Animal studies of facial development are a powerful tool both for identifying candidate genes and for functional analyses of candidate genes from human studies.

Facial shape and allometry quantitative trait locus intervals in the Diversity Outbred mouse are enriched for known skeletal and facial development genes

“…Collectively, the studies report around 50 loci for facial morphology [24]. While there is limited overlap in the candidate gene sets among studies [25], and though many of the individual genes have no previously known role in facial development [3], the genes that do replicate across GWAS (PAX 1, PAX3, HOXD cluster genes, DCHS2, SOX9) are known to be important to facial and/or skeletal morphogenesis.…”

Substantial Improvements in Facial Morphology through Surgical-Orthodontic Treatment: A Case Report and Literature Review

“…These anatomic features can present many quantitative and qualitative variations. Facial development patterns and facial features, including changes in the proportions of the length and width of some facial characteristics, are significantly influenced by environmental factors such as culinary habits and their involvement in the functional capacity and the size of masticatory muscles, swallowing patterns, breathing patterns, and oral habits [1].…”