Identification of body fluid using tissue-specific DNA methylation markers

Abstract

Determination of type and origin of body fluids found at crime scenes can provide important clues for forensic investigation. Recently, DNA methylation markers have proved to be a new promising tool for forensic body fluid identification. The goal of this study is to identify CpG sites that display body fluid-specific differentially methylation patterns as DNA methylation markers for forensic purpose. Using pyrosequencing technique, we examined five tissue-specific differentially methylated regions (tDMRs) for the genes BIK, CYTH4, GAS2L1, MDFI, and OSM on five different body fluids (venous blood, saliva, semen, menstrual blood and vaginal). Of the tested tDMRs, four showed different DNA methylation profiles in five body fluids (P<0.05). The differences were unrelated to age and gender of body fluid’s carrier (P>0.05). A body fluid identification assay based on four body fluid-specific DNA methylation markers was set up and evaluated in 40 body fluid samples. The assay could discriminate five body fluids with high sensitivity and specificity. Our results indicated that the set of body fluid-specific CpG sites could become useful DNA markers for forensic analysis of body fluids.