Methylation Markers for the Identification of Body Fluids and Tissues from Forensic Trace Evidence

The identification of body fluids is an essential tool for clarifying the course of events at a criminal site. The analytical problem is the fact that the biological material has been very often exposed to detrimental exogenous influences. Thereby, the molecular substrates used for the identificatio...

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Bibliographic Details
Published in:PloS one 2016-02, Vol.11 (2), p.e0147973-e0147973
Main Authors: Forat, Sophia, Huettel, Bruno, Reinhardt, Richard, Fimmers, Rolf, Haidl, Gerhard, Denschlag, Dominik, Olek, Klaus
Format: Article
Language:English
Subjects:
Analysis
Biological materials
Biology and life sciences
Biomarkers - metabolism
Blood
Body fluids
Body Fluids - metabolism
Cancer
Cervical carcinoma
Cervix
Collaboration
Computer Simulation
Crime
Deoxyribonucleic acid
Discriminant Analysis
DNA
DNA methylation
DNA Methylation - genetics
Epigenetics
Female
Fluids
Forensic engineering
Forensic Genetics
Forensic science
Forensic serology
Gene expression
Genetic aspects
Genetic Loci
Genome, Human
Genomes
Haplotypes
Humans
Identification
Loci
Male
Markers
Mathematical analysis
Medicine and Health Sciences
Menstruation
Methylation
Organ Specificity
Physical Sciences
Physiological aspects
Planck, Max
Polymorphism, Single Nucleotide - genetics
Proteins
Reproducibility of Results
Saliva
Single-nucleotide polymorphism
Social Sciences
Sperm
Studies
Substrates
Target recognition
Tissues
Tumors
Vagina
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Summary:The identification of body fluids is an essential tool for clarifying the course of events at a criminal site. The analytical problem is the fact that the biological material has been very often exposed to detrimental exogenous influences. Thereby, the molecular substrates used for the identification of the traces may become degraded. So far, most protocols utilize cell specific proteins or RNAs. Instead of measuring these more sensitive compounds this paper describes the application of the differential DNA-methylation. As a result of two genome wide screenings with the Illumina HumanMethylation BeadChips 27 and 450k we identified 150 candidate loci revealing differential methylation with regard to the body fluids venous blood, menstrual blood, vaginal fluid, saliva and sperm. Among them we selected 9 loci as the most promising markers. For the final determination of the methylation degree we applied the SNuPE-method. Because the degree of methylation might be modified by various endogenous and exogenous factors, we tested each marker with approximately 100 samples of each target fluid in a validation study. The stability of the detection procedure is proved in various simulated forensic surroundings according to standardized conditions. We studied the potential influence of 12 relatively common tumors on the methylation of the 9 markers. For this purpose the target fluids of 34 patients have been analysed. Only the cervix carcinoma might have an remarkable effect because impairing the signal of both vaginal markers. Using the Illumina MiSeq device we tested the potential influence of cis acting sequence variants on the methylation degree of the 9 markers in the specific body fluid DNA of 50 individuals. For 4 marker loci we observed such an influence either by sole SNPs or haplotypes. The identification of each target fluid is possible in arbitrary mixtures with the remaining four body fluids. The sensitivity of the individual body fluid tests is in the same range as for the forensic STR-analysis. It is the first forensic body fluid protocol which considers the exogenic and endogenic parameters potentially interfering with the true results.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0147973