An analysis of data curated from 5 years of identifying human remains

Abstract

An archive of 5 years of cases involving the identification of human remains was curated, collecting information on: The sample type submitted, the number of STR loci yielding interpretable results, the kinship challenge posed, and the outcome for the case. A total of 129 cases of remains ID were investigated using manual DNA extraction and recovery methods with amplification of STR markers using the Power Plex 21 multiplex STR kit from Promega Corp. In 52 cases, blood spots collected by the ME were provided as sample and in 100% of those cases, probabilities of relatedness to the reference samples was ≥99%. In 77 cases, tissue other than blood was provided as a source of DNA. These other samples were grouped categorically into long bones (femur and tibia; 40 cases), skull bones/teeth (11 cases), other bones (16 cases), and tissue (normally adherent to bone) (10 cases). Reference samples provided for cases included alleged parents or child(ren) of the victim (86 cases), alleged full siblings of the victim (38 cases), or alleged second‐order relatives (five cases). The overall success rate in confirming the identity of the source of the remains in these cases was 89.2%. Our results demonstrate that a laboratory can be often successful identifying human remains using methods easily implemented in any DNA typing laboratory.

A comparison between petrous bone and tooth, femur and tibia DNA analysis from degraded skeletal remains

“…Genetic profiles data (both mean and coefficient of quartile variation) are presented in Table 3, and boxplots of each parameter by sample type are shown in Figure 3. The maximum average value of detected alleles above 50 RFU was observed in tooth (30), followed by petrous bone (29), femur (24), and tibia (23). Filtering by stochastic threshold, petrous bone was the best with an average of 20 alleles, followed by tooth (19) and femur and tibia (12).…”

“…Petrous bone has been pointed out in ancient DNA research as the remain with the largest amount of endogenous DNA quantity, with higher C→T damage rate and smaller mitochondrial DNA/nuclear DNA ratio, and high sample to sample variation [28]. In forensic literature, larger DNA quantities have been obtained from long bones [30], such as tibia [8,31,32], while other studies obtained better yields from petrous bone rather than from femur or teeth [10,29,[33][34][35][36]. Petrous bone generally yields high DNA quantities and low degradation index [35,37].…”

“…Discrepancies between the quantification results by commercial qPCR kits and the obtained genetic profile have already been discussed [41] when it comes to this kind of challenging samples, not only in autosomal STRs analyses but also in mitochondrial DNA approaches [42]. As seen in quantification data discussion, long bones samples in general [30], and femur samples in particular [7,8,43], have been reported as the sample type thar yields the best DNA profiles. Teeth samples achieved good results taking into account the low (compared to petrous bone) DNA yields previously assessed by qPCR, as it has been stated [37].…”