[The usefulness of SNP markers for analyses of highly degraded biological materials]

The most common cause of problems associated with analyzing DNA extracted from forensic samples is their high level of degradation. Such difficulties are caused by the fact that STR markers have too large amplicon sizes to be amplified in degraded DNA samples. Thus, it is necessary to employ more efficient markers for analyzing evidential samples. SNPs are ideal tools for such purposes, for the SNP genotyping method does not require large amplicon size, and thus increases the possibility of amplifying degraded DNA samples. Although single SNP is not polymorphic enough, we can obtain sufficient results by examining several SNPs. The aim of this study was to examine the usefulness of the SNP-pentaplex (rs2294067, rs2282160, rs2070764, rs2277216, rs1063739) for forensic applications by analysing several forensic cases, which were impossible to solve in a range of STR markers because of highly degraded DNA. DNA fragments were amplified in one multiplex PCR reaction, which contained 5 primer pairs. SNPs were subsequently identified in a minisequencing reaction and gel electrophoresis in an ABI Prism 377 Sequencer. The research confirmed the usefulness of SNP-pentaplex for forensic applications. Despite employing mainly degraded and low copy number DNA, full genetic profiles were obtained in almost every sample. Although the discrimination power of SNP-pentaplex is not sufficient for obtaining adequate evidential value, it seems to be an ideal screening method for forensic applications.