Application of DNA methylation-based markers in identification of mixed body fluid evidences simulating crime scene scenarios

• Main Authors: Rania Gomaa, Lamis Nader, Jumana Jamal
• Format: Article
• Language: English
• Published: SpringerOpen 2021-06-01
• Series: Egyptian Journal of Forensic Sciences
• Subjects: DNA; RNA; Body fluid identification; Epigenetics; DNA methylation; Bisulfite conversion
• Online Access: https://doi.org/10.1186/s41935-021-00226-6

Abstract Background Epigenetic modifications are heritable and follow a non-mendelian inheritance pattern. They do not alter the DNA sequence but affect the gene expression at the transcriptional level. DNA methylation is one of these epigenetic changes and it is characteristic to each tissue and shows specificity with respect to developmental stage and age. Due to its specificity and reliability, it has emerged as a valuable tool in forensic investigation. Biological samples, such as blood, saliva, semen, or hair found at the crime scene can be used to isolate DNA and study the methylation pattern. Recent developments in molecular biology techniques allowed the study of the effects of methylation in specific tissues. DNA methylation specificity is very intense. These specific markers can be used to identify the tissue type such as blood, saliva, or semen at the crime scene and helps in the identification of the culprit. The present study aimed to validate the use of DNA methylation body fluid-specific markers in the identification of peripheral blood, menstrual blood, and semen. Additionally, it aimed to investigate the potential use of such DNA methylation markers for the identification of different body fluids mixtures simulating forensic science scenarios. Different DNA methylation markers were studied in different body fluid samples (peripheral blood, menstrual blood, and semen) individually and as mixtures. DNA extraction and bisulfite conversion were performed and followed by real-time PCR. Results The results of real-time PCR and the statistical analysis showed that the SPERM2 marker was better than SEU2 in the identification of semen DNA in mixed samples. However, in the identification of individual semen samples, the later marker showed better results than the first one, whereas BLM1 and MENS1 markers were successful in identifying the peripheral and menstrual blood samples, respectively. Conclusions This data can be readily used and applied on different forensic samples for tissue identification. Further sequencing studies are strongly recommended.