Application of an established canine genotyping method to a sequence-based approach

The advancement and accessibility of high throughput sequencing platforms have transformed forensic biology, with sequence-based genotyping of various genetic markers being widely validated for use. A key requirement for the successful implementation of such an approach for genotyping short tandem repeat (STR) loci is backward compatibility with existing databases derived from conventional capillary electrophoresis (CE). Other advantages of a sequence-based approach include novel allele discovery and increased allelic diversity. While sequence-based STR genotyping of human material is now relatively common in forensic biology, this approach for genotyping other animal species for forensic applications has been slower to emerge.

Here we present proof-of-concept and concordance data for the sequencing of a canine STR panel for forensic applications. Sequence-based genotyping using the Mini-DogFiler panel is presented herein, including a bioinformatics pipeline for genotype calling. Allele discovery is presented as well as backward compatibility of sequence-based data with CE-derived genotypes of the same samples using the DogFiler and/or the Mini-DogFiler panel(s). The recorded CE genotypes, which included domestic dog and wolf samples, were compared to those generated using the sequence-based approach. General database statistics were evaluated across samples and included a comparison of the number of unique genotypes and alleles observed when using CE genotyping as compared to sequencing. The results demonstrate this method as being concordant and backward compatible to traditionally generated CE data. With additional developmental validation work, this approach offers a unique and timely addition to the suite of tools available for use to support animal and wildlife forensic science.