Bone and Dental DNA Damage Due to Extreme High-Temperature Exposure Through STR-CODIS, Y-STR and MtDNA Examinations

Background: Forensic experts play an important role in forensic science. Identification through DNA analysis is an accurate and stable diagnostic tool. However, along with the development of DNA material examination, problems arise since DNA undergoes degradation, commonly known as degraded DNA. High-temperature exposure is one factor in DNA degradation. Bone and dental tissues are among the materials most resistant to this degradation. Bone and teeth are the most solid parts of the human body because they contain hydroxyapatite and extracellular matrices that protect DNA (nuclear DNA and mtDNA). DNA degradation due to high-temperature exposure on bone and dental DNA samples in forensic identification has been extensively unknown. Objective: This study aimed to analyze DNA damage derived from ribs and second molar teeth caused by extremely high temperatures using a short tandem repeat (STR) CODIS marker. Methods: This research analyzes DNA degradation of bone and dental materials due to effect ofhigh-temperature exposures (500⁰C, 750⁰C, 1 000⁰C, and 1 250⁰C for 20, 30, and 40 minutes) based on the loci STR and mini-STR CODIS (CSF1PO, D18S51, D21S11, FGA, D8S1179, D5S820, D7S820, D13S317, D16S539), Y-STRs (DYS19, DYS389, DYS390) and 143-bp and 126-bp mtDNA. Samples consisted of 24 ribs and 24 molars from 7 cadavers. Results: The analysis showed that teeth were more resistant than bones in protecting DNA from high-temperature exposure. This could be seen in the number of presentations positively detected from lociSTR, Y-STRs,and mtDNA. Loci of STR CODIS of bone materials detected by standard primer were D3S1358, D16S539 (1 2500C-20’) and CSF1PO (5000C-40’); those of dental materials were D7S820, D8S1179 (1 2500C- 40’), D3S1358 (1 2500C-20’), D13S317 (1 0000C- 40’), D16S539 (7500C-40’), CSF1PO (7500C-20’). Loci of STR CODIS of bone materials detected by mini primer were D16S539 (7500C-40’), CSF1PO, D12S137 (5000C-40’), and D3S358 (5000C-30’); those of dental materials were CSF1PO (1 2500C- 40’), D16S539 (1 0000C-20’), D13S317 (7500C-40’), D3S1358 (7500C-20’), D5S818, D7S820, D8S1179,D18S51 (5000C-40’). The detected locus of Y-STRs of bone materials was DYS389I (1 2500C-20’); that of dental materials was DYS389I (1 2500C-40’). mtDNA was detected at 143 bp (7500C-40’ for bone materials and 1 2500C-30’ for dental materials) and 126 bp (7500C-40’ for bone materials and 1 0000C-30’ for dental materials). Conclusion: Undetected mini primer on DNA amplification of high-temperature exposed bones and teeth might be due to complete degradation, resulting in DNA fragments losing their primer annealing sites. Differences in amplicon products and GC content of DNA templates content supported the successful detection of those loci at the maximum exposure of the research. The ratio of GC content for CSF1PO was 42.6 %, D8S1179 was 30.9 %, and D7S820 was 28.6 %, and had power discriminant of different. In conclusion, dental materials that remained capable of detection were loci D7S820 and D8S1179 with standard primer, CSF1PO with mini primer, and DYS389I at the maximum temperature exposure (1 2500C for 40 minutes).