Establishment and validation of a DIP panel for forensic ancestry inference and personal identification

Biallelic Deletion/Insertion polymorphisms (DIPs), known for their significant diversity across various populations, serve as valuable markers for forensic ancestry inference and personal identification. In this study, we utilized DIPs to provide a potentially powerful forensic examination tool specifically tailored for East Asian populations. Our focus on ancestry allows us to delve deeper into the genetic signatures that characterize this diverse group, offering enhanced resolution in forensic analyses.

A total of 56 autosomal DIPs, 3 Y-chromosome DIPs, and the Amelogenin were selected to build the 60-panel. Population genetic parameters, principal component analysis (PCA), STRUCTURE analysis, and phylogenetic tree construction were employed to evaluate the capacity for ancestry inference. The verification guidelines recommended by the Scientific Working Group on DNA Analysis Methods were followed in the developmental validations of the 60-panel.

The PCA, STRUCTURE, and phylogenetic tree constructions were not only consistent with each other but also corroborated by previous research. The combined probability of discrimination and the cumulative probability of paternity exclusion values were 0.999999999999 and 0.9937, respectively. These values indicate that the 60-panel is not only a useful tool for personal identification testing within the East Asian population but also provides valuable biogeographic information. Furthermore, the validation study of the 60-panel, which included assessments of PCR conditions, sensitivity, species specificity, stability, mixture analysis, reproducibility, and case sample studies, as well as analysis of degraded samples, demonstrated that the panel is well-suited for forensic testing. The panel's performance was particularly notable in the analysis of degraded samples, showcasing its potential for use in challenging forensic cases.

The newly developed 60-panel demonstrated robust performance in validation tests, yielding reliable genotypes even from poor-quality samples like degraded DNA. It offers valuable biogeographic insights and sufficient polymorphism for personal identification, which assisted forensic examinations in East Asian populations.