Integrating physical anthropological techniques and emerging methodologies using a quasi-landmark mesh to decode the upper facial region from DNA

Abstract

Genetic identification currently relies on comparing unknown DNA samples against reference profiles in forensic databases or indubitable individuals. However, when no match is available, these cases may remain unsolved. In such circumstances, advances in Forensic DNA Phenotyping (FDP), that seeks to determine externally visible characteristics (EVCs) from DNA, could assist in identification efforts. Among EVCs, facial shape is of particular interest. While genomewide association studies (GWAS) have identified potential SNPs linked to facial traits, these vary between populations and methodology. Addressing this issue, the present study has selected a set of candidate SNPs and assessed their correlation with facial phenotype in a Spanish population, focusing on the upper facial region, which includes the highly informative ocular area. From a collection of 412 individuals, two strategies were performed: one based on traditional anthropometric measurements and indexes with Pearson/Spearman and Chi-squared analyses, and another using a mesh of quasi‐landmarks with canonical correlation analyses. Results revealed significant associations between several SNPs and upper facial metrics, although the SNPs and regions identified differed between the two methods and in part, to previous published results. These findings underline the importance of methodology and validation in population groups in facial description when conducting genetic studies, and most notably, when considering forensic applications.