< Back to previous page

Publication

The complex facial phenotype: new approaches in family-based studies

Book - Dissertation

The human face is a complex trait displaying a strong genetic component, as evidenced by the nearly identical appearance of monozygotic twins, the clear facial resemblances within families and the distinctive facial features associated with particular genetic conditions. Despite the recent advancements in the field of facial genetics, our current understanding of the genes contributing to the heritable components of the face remains largely incomplete. Adequate methods to characterize human facial morphology appear to be one of the major bottlenecks towards further progress, which traditionally have been limited to simple anthropometric measurements (e.g. distances, angles) that are measured between specific points or landmarks on a set of 2D or 3D facial images. In this thesis, we push forward the current understanding of facial genetics in health and disease through innovative phenotyping strategies, starting from the genetic and resulting phenotypic similarity within families. One focus was the decomposition of the facial phenotype through heritability studies by segmenting the face into novel, global-to-local phenotypes based on the biological mechanisms of inheritance. In a second project, the shared facial morphology between pairs of siblings was explored in a biometric identification task, from which a series of facial traits were defined. Genetic loci contributing to normal-range variation of these traits were identified through genome-wide association scans. Next, the sibling-informed phenotyping approach was applied to another ancestral distant population of African descent and the overlap in genetic loci was investigated. In a final stage, the assessment of facial similarity between siblings was extended towards nuclear families to establish a model of normal inheritance. Deviation from the expected model was then used towards an objective and contextual definition of facial dysmorphism.
Publication year:2021
Accessibility:Open