SNP for ID 52-plex in casework samples: “Cracking” bones and other difficult samples

Abstract

Casework samples can present difficulties to forensic scientists in criminal and identification investigations. Some challenging samples like bones, teeth and crime scene samples, often contain low DNA quantity which can even be degraded. In these cases, obtained STR profiles are many times incomplete or even null. This is partly due to relative bigger size of commonly used STRs in forensic analysis. In order to bypass this problem, other strategies of analysis have been developed in the past based on mini-STRs and biallelic markers, such as Indels and SNPs. Although each marker type has its advantages and disadvantages, SNPs benefit from the fact of having smaller amplification products and its analysis can be realized analyzing simultaneously a great number of loci using large multiplexes. One of such multiplex is SNPforID 52-plex which analyzes 52 loci, providing good results, as reported by some authors. Taking this in consideration, we compared the amplification success of 53 real casework samples from our casuistic consisting of bones, teeth and other samples using the 52-plex and the Identifier 1 Plus kit. Mean amplification success rate by loci was of 73% and 43% respectively and 16 out of 36 samples in which STR profiles were not obtained or in which these were poor, generated complete or almost complete SNP profiles. We conclude that the 52-plex can be a valuable tool in the analysis of different types of challenging forensic samples when STRs fail to provide necessary genetic information for identification. 2015 Elsevier Ireland Ltd. All rights reserved.