Comparison of forensic parameters between length-based and sequence-based STR models / 中国法医学杂志

ABSTRACT

Capillary electrophoresis-based STR genotyping is accepted as the gold standard for human individual identification. Next generation sequencing (NGS) allows for the full resolution of STR base composition, and has the potential to be widely used in the field of forensics. Compared with length polymorphism, STR sequencing could provide more information, and quantitatively calculating the forensic parameters is necessary. In this paper, we established simple models for length-based and sequence-based STRs, and calculated the forensic parameters for both models. The results showed that for a single STR locus, compared with length polymorphism, STR sequence polymorphism could provide higher power of discrimination and power of exclusion, indicating sequence-based STR marker have stronger ability for identifying unrelated individuals and exclude non biological father. By combining 15 non-linkage loci for forensic DNA analysis, the cumulative matching probability values for length-based and sequence-based STR models are at 10-18and 10-26levels, respectively. Only 10 non-linkage sequence-based STR is required to reach a cumulative matching probability of as high as 15 length-based STR loci. It is hoped that these simulated models and calculations can provide a reference for the forensic application of NGS-based STR genotyping.