Evaluation of an ancestry prediction strategy for historical military remains using a World War II-era sample and pedigrees with family-level admixture

Errors in ancestry prediction for historical military casework result in soldiers unable to be interred to the country they fought and died for. Australian WWII soldiers with varying degrees of European and Asian heritage are expected in the remains recovered in the Asia-Pacific, representing the greatest risk of error for Unrecovered War Casualties-Army (UWC-A). Previous research using the Ghaiyed population-specific panel (GPSP), on a modern British sample, demonstrated less variation in family-level admixture compared to four global ancestry panels. This suggested that the targeting of specific populations of interest may improve accuracy, although an evaluation using a sample of WWII-era European-Australians (W2A) with varying degrees of family-level admixture was required. This paper outlines the development of an ancestry prediction strategy using a W2A sample (non-admixed), and simulation of 4,000 genotypes representing Australian pedigrees with one Japanese ancestor (great-great-grandparent, great-grand-parent, grandparent, and parent). All great-great-grandparent to grandparent profiles were accurately predicted as W2A individuals, and although admixture at the parent level could not be resolved, no profiles were incorrectly assigned Japanese ancestry. The GPSP provided more informative predictions in contrast with the mitochondrial DNA/Y-chromosome lineage approach currently used by UWC-A as the GPSP provides an approximately 75% improvement.