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Article
The determination of tissue-specific DNA methylation patterns in forensic biofluids using bisulfite modification and pyrosequencing
Electrophoresis
  • Tania Madi, Florida International University
  • Kuppareddi Balamurugan, The University of Southern Mississippi
  • Robin Bombardi, The University of Southern Mississippi
  • George Duncan, Broward County Sheriff's Office Crime Laboratory
  • Bruce McCord, Florida International University
Document Type
Article
Publication Date
3-1-2012
Keywords
  • Biofluids,
  • DNA,
  • Epigenetic,
  • Forensic,
  • Methylation,
  • Pyrosequencing
Abstract

The goal of this study is to explore the application of epigenetic markers in the identification of biofluids that are commonly found at the crime scene. A series of genetic loci were examined in order to define epigenetic markers that display differential methylation patterns between blood, saliva, semen, and epithelial tissue. Among the different loci tested, we have identified a panel of markers, C20orf117, ZC3H12D, BCAS4, and FGF7, that can be used in the determination of these four tissue types. Since methylation modifications occur at cytosine bases that are immediately followed by guanine bases (CpG sites), methylation levels were measured at CpG sites spanning each marker. Up to 11 samples of each tissue type were collected and subjected to bisulfite modification to convert unmethylated CpG-associated cytosine bases to thymine bases. The bisulfite modified DNA was then amplified via nested PCR using a primer set of which one primer was biotin labeled. Biotinylated PCR products were in turn analyzed and the methylation level at each CpG site was quantitated by pyrosequencing. The percent methylation values at each CpG site were determined and averaged for each tissue type. The results indicated significant methylation differences between the tissue types. The methylation patterns at the ZC3H12D and FGF7 loci differentiated sperm from blood, saliva, and epithelial cells. The C20orf117 locus differentiated blood from sperm, saliva, and epithelial cells and saliva was differentiated from blood, sperm, and epithelial cells at a fourth locus, BCAS4. The results of this study demonstrate the applicability of epigenetic markers as a novel tool for the determination of biofluids using bisulfite modification and pyrosequencing.

DOI
10.1002/elps.201100711
Citation Information
Tania Madi, Kuppareddi Balamurugan, Robin Bombardi, George Duncan, et al.. "The determination of tissue-specific DNA methylation patterns in forensic biofluids using bisulfite modification and pyrosequencing" Electrophoresis Vol. 33 Iss. 12 (2012) p. 1736 - 1745 ISSN: 0173-0835
Available at: http://works.bepress.com/george-duncan/14/