The potential of human leukocyte antigen alleles to assist with multiple-contributor DNA mixtures: Proof of concept study

One of the most challenging issues still present in forensic DNA analysis is identifying individuals in samples containing DNA from multiple contributors. The introduction of further novel identification markers may be a useful tool in the deconvolution of such DNA mixtures. In this study, we investigated the potential of alleles from the human leukocyte antigen system (HLA) to aid in identifying individuals in complex, multiple-donor DNA samples. The most advantageous characteristic of the HLA complex is its polymorphism in the human genome. A 22-loci multiplex with HLA markers was designed and then applied to two-, three- and four-person DNA mixtures. The results of the conducted experiments demonstrated that the identification of individuals in multiple contributor samples with the help of HLA markers is possible, however, it is clear that the reliability of the method is heavily dependent on the number of unique alleles for each individual in the analysed mixture. In order to compare this novel approach against the already established method, the same group of reference and multiple-contributor samples was analysed with a commonly used set of STR markers. This proof-of-concept research shows the importance of examining alternative solutions to the current deconvolution challenge in forensic DNA profiling.