Evaluation of forensic DNA profiling success on teeth that have been submerged in the ocean

Deceased humans that are recovered from marine environments contribute to the burden of unidentified bodies, both globally and in South Africa. Compromised conditions of these bodies make identification difficult. In these instances, DNA analysis becomes an invaluable tool for identification. Nonetheless, there is a notable gap in existing literature regarding the use of DNA from teeth for identifying human remains recovered from marine environments. This study therefore aimed to evaluate forensic DNA profiling success on human teeth samples (n = 90) that were submerged in two different marine locations along Cape Town's coastline. Thirty adult volunteers each donated three wisdom teeth, where each tooth per individual was subjected to a different condition for 20 days: one was submerged in False Bay, one was submerged in Table Bay and the remaining tooth was kept as an unsubmerged, matched control in the laboratory. DNA was extracted and quantified using quantitative polymerase chain reaction before undergoing DNA profiling. No significant difference was observed in the likelihood ratio between DNA recovered from samples submerged in Table Bay (median: 1.031 × 1013; range: 4.221 to 5.633 × 1031) compared to False Bay (median: 3.501 × 1015 range: 1.557 × 103 to 2.578 × 1035). As expected, matched control samples yielded significantly higher DNA concentrations than submerged samples and showed significantly higher Likelihood ratios (median: 3.094 × 1028; range: 11.11 to 1.614 × 1033) than submerged samples (p < 0.001). Three DNA profiles from False Bay samples showed no allele detection and therefore were uninformative. Further, allele drop-ins were observed in three DNA profiles from False Bay samples but none in Table Bay samples. These were hypothesised to be due to the presence of marine microbial DNA and could potentially confound DNA interpretations. Overall, the results suggested that the protocol used was suitable for DNA profiling of teeth samples recovered from Table Bay and further research is required to obtain insight into aquatic conditions affecting samples submerged in False Bay.

Grantor dc:publisher.institution

Department of Pathology

Year dc:date.issued

2025

Author dc:creator

• Mphaka, Francina Dimpho

Advisors dc:contributor.advisor

• Heathfield, Laura
• Martin, Donna-Lee

• False Bay
• Deceased
• Human
• DNA

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/11427/42539

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/42539