Short tandem repeats (STRs) have been applied in various aspects of human identification in forensic investigations for nearly 20 years. The sets of highly polymorphic STRs are the gold standard for forensic DNA profiling. However, in some cases (e.g., highly degraded DNA, low amounts of DNA, no reference DNA) the application of STRs DNA profiling is challenging in human forensic investigation. For example, if the unknown STRs profile does not match that of a known suspects profile or any from a criminal DNA database, and if no other evidence is present, the investigation has lost any leads to pursue. Moreover, the investigation becomes more chaotic where countries have no DNA database of criminals. In such case other genomic markers could be used for the lighting the case.
In the last few years, novel DNA markers and applications have been developed thanks to the wide ranging and accelerating advances in genomics. Recently, SNPs (Single Nucleotide Polymorphisms) have been utilized in novel applications such as the analysis of Externally Visible Characteristics (EVCs) (i.e., eye, hair and skin color). Information about the physical characteristics of the suspect can be predicted from the biological evidence using DNA technologies. Eye and hair color physical characteristics, are the most well-known variations of human pigmentation. The HIRISPLEX system has been developed for eye and hair color estimation with 24 SNP regions. Hirisplex panel can contribute to the direction of the investigation and to quickly clarify the case in unsolved cases or in identifying missing persons and disaster victims.
We apply the SNaPshot minisequencing as well as next generation sequencing (NGS) techniques for the typing of the targeted SNP markers. The prediction accuracy is 90% for the blue and brown eye color and 74% for the hair color. We provide these analyzes as a service in our partner laboratory.