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In this dissertation novel marker system were characterized and evaluated for their ability to discriminate between forensically relevant body fluids with a specific focus on simultaneous detection within mixtures. Two different methods were investigated in detail for this purpose: DNA methylation pattern analysis and immunochromatographic assays. The potential use of DNA methylation markers for the identification of body fluids has been indicated by recent advances in whole genome epigenetic analyses and proposed markers for the detection of blood, vaginal secretions, semen, and saliva were evaluated in this work. Markers were identified and validated for the identification of menstrual fluid, semen, and saliva in single source stains as well as in mixtures of several body fluids. Subsequently, four markers were combined into a multiplex array for the simultaneous detection of these body fluids. Additionally, DNA methylation markers were identified for the discrimination of menstrual fluid and blood, which can be especially useful in alleged sexual assaults. With the results of this work it was shown that DNA methylation pattern analysis might be an advantageous alternative over existing methods for forensic body fluid identification. Furthermore, the high potential of protein markers for menstrual fluid identification is presented in this work. With these assays the identification of menstrual fluid is based on the detection of D- dimers, the highly abundant product of fibrinolysis in menstrual fluid. An immunochromatographic strip test assay was evaluated and validated for the detection of menstrual fluid and therefore the discrimination of menstrual fluid and peripheral blood. Moreover, the analysis of mixtures of body fluids with immunochromatographic assays was realized by combining commercially available assays into a multiplex array. With this array, the simultaneous detection of five body fluids, i.e. semen, saliva, urine, menstrual fluid, and blood was achieved. The array showed to be highly sensitive and specific, easy in use, and the analysis of body fluid mixtures was straightforward. Through the inclusion of novel markers for menstrual fluid and the understanding that immunochromatographic assays have the potential to be multiplexed, these assays also remain a valuable tool in forensic science. |
