DNA degradation in human teeth exposed to thermal stress

Diego Lozano-Peral,Leticia Rubio,María Jesús Gaitán,Enrique Viguera,Stella Martín-De-Las-Heras,Ignacio Santos

doi:10.1038/s41598-021-91505-8

Diego Lozano-Peral, Leticia Rubio + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-91505-8

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Abstract

Human identification from burned remains poses a challenge to forensic laboratories, and DNA profiling is widely used for this purpose. Our aim was to evaluate the effect of temperature on DNA degradation in human teeth. Thirty teeth were exposed to temperatures of 100, 200, or 400 °C for 60 min. DNA was quantified by Real-Time qPCR (Quantifiler Human DNA Quantification Kit) and fluorescence spectroscopy (Qubit 3.0 Fluorometer). DNA degradation was evaluated by using STR markers (AmpFLSTR Identifiler Plus PCR Amplification Kit) to determine the allele and locus dropout, inter-locus balance, and degradation slope (observed (Oa) to expected (Ea) locus peak height ratio against the molecular weight). Most of the genomic DNA was degraded between 100 °C and 200 °C. At 100 °C, locus dropout ratios showed significant differences between the largest loci (FGA, D7S820, D18S51, D16S539, D2S1338 and CSF1PO) and amelogenin. Inter-locus balance values significantly differed between all dye channels except between NED and PET. The dropout ratio between D18S51 (NED) and amelogenin (PET) can be recommended for the evaluation of DNA degradation. The Oa/Ea regression model can predict locus peak heights in DNA degradation (R2 = 0.7881). These findings may be useful to assess the reliability of DNA typing for human identification in teeth subjected to prolonged incineration.

Highlights

Human identification from burned remains poses a challenge to forensic laboratories, and DNA profiling is widely used for this purpose
DNA measurements have been reported to vary among different quantification methods[44], we found no significant difference in mean concentrations between Quantifiler and Qubit in the control or 100 °C groups
After 60 min of incineration, all short tandem repeat (STR) loci were detected in all teeth exposed to 100 °C, but genetic identification was almost impossible from teeth exposed to temperatures of 200 °C and above

Summary

Introduction

Human identification from burned remains poses a challenge to forensic laboratories, and DNA profiling is widely used for this purpose. Human identification from burned remains poses a challenge to forensic laboratories It is required in a wide range of situations, including major disasters, terrorist attacks, and car accidents, among o thers[1,2,3,4], and DNA typing is the usual approach. There is a need for in-depth investigation to determine the degree of DNA degradation in teeth burned at different temperatures and time of exposures. The objective of this study was to quantify the DNA in teeth exposed for 60 min to temperatures of 100, 200, or 400 °C and evaluate its degradation by examining locus dropout, peak height dropout ratio, inter-locus balance, and degradation slope

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