The role of NGS mitogenomes and DNA phenotyping in the forensic investigation:a casework of newborn abandoned in a dumpster

Inside a large bag collected in a dumpster, a newborn was found, noticed due to the cries heard by passersby. When discovered in May 2013, the female infant, still alive, was wrapped in several towels soiled with widespread bloodstains. Additionally, the placenta and umbilical cord were also recovered near the baby. At first, the placenta samples from the mother's side were analysed to genotype autosomal DNA profile and mtDNA haplotype using the Sanger method for the HVS-I and HVS-II regions to determine the potential ancestral background of the unknown mother. The predicted haplogroup based on mutations in the control region was H27, which was predominantly found in northern Europe. In addition, biogeographic ancestry and DNA phenotyping analyses were performed using the Precision ID Ancestry Panel which targets 165 ancestry informative autosomal Single Nucleotide Polymorphisms (SNPs) and the 41 HIrisPlex-S markers respectively, on the Ion GeneStudio S5 Prime System. The results showed the mother's sample to have a predicted predominant European ancestry with Southwest Asian admixture. To increase the informativity, a massively parallel sequencing (MPS) experiment was performed using the Ion PGM system to analyse the entire mitogenome. The results revealed new mutations in the coding regions, leading to the assignment of a different haplogroup (H2a5), exclusively found in the Franco-Cantabrian area. The HIrisPlex-S web tool predicted dark brown hair with a light shade, green eye colour, and an intermediate skin phenotype. This case is an example of the impact of the development of new forensic markers and technologies considering that DNA-based inference of biogeographic ancestry should include ancestry-informative autosomal, Y-chromosomal and mitochondrial DNA markers to infer an individual’s subcontinental ancestry. Combined DNA analysis of external visible characteristics (EVCs) and biogeographic ancestry can increase the information yield of a criminal investigation.