Targeted capture and sequencing of 1245 SNPs for forensic applications

Next generation sequencing (NGS) technologies have enabled the possibility of analyzing a large number of SNPs simultaneously from multiple samples in a single experiment, for complementing the shortcomings of STR based methods. To efficiently genotype the desired SNPs, it is critical to optimize the library construction procedures. In this study, we formulated a strategy combining the molecular inversion probe (MIP) based target region capture method and NGS for genotyping 1245 SNPs. All the SNPs we selected exhibited high heterozygosity (minor allele frequency (MAF) > 0.3) according to 1000 genomes data. We applied the method to genotype a population of 210 unrelated individuals from the Hubei province of China and assessed the allele frequencies, Hardy-Weinberg equilibrium and linkage disequilibrium. The MAFs of more than 95% of the SNPs were ≥0.2, and no significant deviation or strong linkage was observed for 98% of the SNPs. The data indicated that, even within a relatively confined region, our SNP panel is suitable for individual identifications. Furthermore, we performed paternity test for 7 trio families using low quality DNA samples. The conclusions are in total agreement with these of STR-based analyses, with higher confidence indexes. Finally, we evaluated the performance of the MIP-NGS method with mock degraded DNA samples. We were able to genotype most of the SNPs even when the genomic DNA was sonicated to ˜100 bp range. In summary, we established a highly accurate and cost-effective method of SNP genotyping, which is potentially capable of solving complex issues encountered in forensic practices.