Exploring the usefulness of microhaplotypes in forensic identification using massive parallel sequencing technology

BACKGROUND: Microhaplotypes or microhaps (MH) were recently introduced in the landscape of forensic genetic and appear to be useful for identification purposes, genotyping of degraded DNA, reconstruction of family relationships, ancestry prediction and DNA mixtures deconvolution. In order to make inference about a set of microhaps useful in forensic casework with low amount of degraded DNA and useful in kinship analysis, several microhaps were tested by massive parallel sequencing (MPS) assay. METHODS: We have investigated the effectiveness of 29 microhaps in a set of real forensic samples together with artificially degraded DNAs. Moreover, we explore the informativeness of 87 microhaplotypes in relationship analysis through a simulation of different kinship testing scenarios typically encountered in forensic identification. RESULTS: The MPS coverage analysis showed a good performance of the designed panel. Full profiles could be obtained with 0.1 ng of input DNA even with highly degraded samples. The increment of the number of PCR cycles does not result in an improvement in genotyping results in samples with low amounts of DNA, as the increase of drop-in and drop-out events were observed at 25 number of PCR cycles. No correlation between amplicons size and occurrence of drop-outs and drop-ins was observed. Kinship simulations showed that full siblings and half siblings relationships would be readily distinguished respect unrelated condition using the 87 microhaps panel. CONCLUSIONS: Results shown that microhaps could be a powerful tool for individual identification, relationship resolution and that they are sensitive and reliable in degraded DNA typing.