Assessment of Metastatic Colorectal Cancer (CRC) Tissues for Interpreting Genetic Data in Forensic Science by Applying 16 STR Loci among Saudi Patients

Background: In forensic science, there are cases when the only available provider of biological data is samples of malignant tissues. It can be useful in identification and/or paternity tests. Still, such samples have ambiguities because of microsatellite instability (MSI) and loss of heterozygosity (LOH) effects, being often related to neoplasia. Methods: This research evaluates 16 autosomal short tandem repeat (STR) loci (traditional in forensic investigations) to get genetic data. MSI and LOH were estimated in DNA patterns derived from 73 Saudi respondents (30 healthy individuals and 43 persons with diagnosed colorectal cancer (CRC). Upon deriving DNA from blood, CRC specimens were obtained in both groups, along with the adjoining normal non-cancerous tissues (N-CRC). All specimens and 16 loci (15 STR loci and Amelogenin) were evaluated. Moreover, both colorectal samples were histologically analyzed utilizing HandE staining. Results: Findings revealed non-essential variability in genetic information because of MSI and/or LOH. In CRC, mutations rates were 0.42% (MSI) and 1.62% (LOH). In N-CRC, mutation rates were 0.00% (MSI) and 0.59% (LOH). Further, LOH-related deviations were recorded in 5 loci out of 16. MSI-related deviations were recorded in 4 out of 16 loci, being present in CRC samples only. Genetic deviations within the marker loci might inform about false homozygosity/heterozygosity. Similarly, false gender might come from improper interpretation of DNA profiles. Finally, histopathological trials showed considerable histopathological alterations contrasted to N-CRC. Conclusion: This study is unique in demonstrating the application of 16 autosomal STRs from CRC samples and their comparison with the adjoining N-CRCs in Saudi participants, contributing to the field of forensic science. The experiment revealed no considerable distinctions, while showing that cancer tissues might display MSI and LOH effects that might challenge data interpretation, if STRs are to be applied in the forensic investigation.