Development of a new 32-plex InDels panel for forensic purpose

Insertion/deletion polymorphisms (InDels) have attracted more and more attention of forensic researchers because of their low mutation rate and small amplicons. In the face of challenging forensic cases and degraded DNA, InDels break through the limitations of traditional STRs and provided a new direction for forensic identification. In this study, a multiplex panel consisting of 32 InDels and amelogenin was established and the InDels were selected with minimum allele frequencies (MAF) >= 0.4 in Chinese Han population based on the 1000 Genomes Project and published articles. The 32-plex InDels assay was evaluated using the southern Chinese Han population from Hubei province. All markers were proved to be highly polymorphic with an average observed heterozygosity (H-obs) of 0.4885. The combined power of discrimination (CPD) and the combined probability of paternity exclusion (CPE) were 0.999999999999966 and 0.9982, respectively. Further validation studies indicated that the 32-plex InDels assay was highly sensitive to DNA template amounts as low as 31.25 pg and was effective for degraded DNA. The obtained allele frequencies from this study were compared with published data of other populations.