The presence of specific body fluids at crime scenes could be linked with particular types of crime, therefore attributing a DNA profile to a specific tissue could increase the evidential significance of a match with a suspect. Current methodologies such as tissue-specific mRNA profiling are useful but drawbacks include low tissue specificity and applicability to degraded samples. In this study, the potential of 11 tissue-specific differentially methylated regions, initially identified following large-scale methylation analysis of whole blood, buccal cells and sperm, was explored in order to identify markers for blood, saliva and semen. Bisulphite pyrosequencing analysis supported previous findings, but tissue-specific differentially methylated regions for blood and buccal cells did not show enough specificity to be proposed as markers for blood and saliva, respectively. For some CpGs, a large inter-individual variation in methylation levels was also observed. Two of the semen markers (cg04382920 and cg11768416) were used for further validation on a large set of stains. These two semen-specific assays showed high sensitivity (as low as 50 pg) and stability. Future experiments will shed light on the usefulness of these markers in forensic casework.

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Department of Genetic Identification

Vidaki, A., Giangasparo, F., & Syndercombe-Court, D. (2016). Discovery of potential DNA methylation markers for forensic tissue identification using bisulphite pyrosequencing. Electrophoresis, 37(21), 2767–2779. doi:10.1002/elps.201600261