Project description:Forensic body fluid identification is important for crime scene reconstruction. We used Illumina HumanMethylation 450K bead array containing over the 450,000 CpG sites in 16 body fluid samples to find novel DNA methylation marker for forensic body fluid identification. Examination of genome-wide DNA methylation profiling in 16 body fluid samples
Project description:Forensic body fluid identification is important for crime scene reconstruction. We used Illumina HumanMethylation 450K bead array containing over the 450,000 CpG sites in 16 body fluid samples to find novel DNA methylation marker for forensic body fluid identification.
Project description:Bone is a long-lasting biological tissue often used in forensic investigations as it retains vital biomolecular information commonly used for identification purposes. Bone proteins have attracted interest for their potential in estimating post-mortem interval (PMI) and age-at-death (AAD). However, the preservation of such proteins is highly dependent on intrinsic and extrinsic factors, and these have an impact in the potential application of molecular techniques to forensic sciences. The present study aims at investigating the effect that two commonly used types of burial practices (entombment and inhumation) have on bone protein survival. The sample consists in 14 exhumed individuals from cemeteries in south of Italy at with different AADs (29-85 yeas) and PMIs (1-37 years). LC-MS/MS analyses show that 16 proteins are better preserved in the entombed condition and four in the inhumated one, while no clear cluster separation is detected with principal component analysis. Besides the different burial environments, several potential protein markers are identified for PMI and AAD estimation. Overall, preliminary results show that the two burial environments seem to play a marginal role in the differential preservation of non-collagenous proteins and in the accumulation of post-translational modifications, confirming the potential of LC-MS/MS based proteomics in forensic sciences.
Project description:Characterization of hair proteome in damaged single hairs after an explosive blast and evaluation of success rates in genetically variant peptide marker detection for protein-based human identification.
Project description:Age-related CpG (AR-CpG) sites are currently the most promising molecular markers for age estimation. However, AR-CpG sites for the Han Chinese population have not yet been systematically identified. Besides, there may be high-performance AR-CpG sites beyond the coverage of the commonly used Illumina HumanMethylation450 BeadChip that covers over 450,000 CpG sites (450K), which accounts only 1.6% of CpG sites in the human genome. Therefore, we initiated a project to perform genome-wide methylation analysis on whole blood samples from 42 healthy Han Chinese individuals (21 males and 21 females, 18–62 years) using the newly developed Illumina Infinium MethylationEPIC array that assesses over 850,000 CpG sites (850K) to identify AR-CpG sites for forensic use systematically. The 850K methylation array contains > 90% of 450K CpG sites but adds 413,745 CpG sites. As expected, we not only replicated several high-performance AR-CpG sites previously discovered using the Illumina 450K BeadChip, such as cg16867656 (ELOVL2), cg22454769 (FHL2), and cg10501210 (C1orf132), but also identified 41 (60.3%), 34 (22.5%), and 382 (48.7%) novel AR-CpG sites from the methylation profiles of 21 males, 21 females, and all individuals, respectively.
Project description:Enhancements in sensitivity now allow DNA profiles to be obtained from only tens of picograms of DNA, corresponding to a few cells, even for samples subject to degradation from environmental exposure. However, low-template DNA (LTDNA) profiles are subject to stochastic effects, such as "dropout" and "dropin" of alleles, and highly variable stutter peak heights. Although the sensitivity of the newly developed methods is highly appealing to crime investigators, courts are concerned about the reliability of the underlying science. High-profile cases relying on LTDNA evidence have collapsed amid controversy, including the case of Hoey in the United Kingdom and the case of Knox and Sollecito in Italy. I argue that rather than the reliability of the science, courts and commentators should focus on the validity of the statistical methods of evaluation of the evidence. Even noisy DNA evidence can be more powerful than many traditional types of evidence, and it can be helpful to a court as long as its strength is not overstated. There have been serious shortcomings in statistical methods for the evaluation of LTDNA profile evidence, however. Here, I propose a method that allows for multiple replicates with different rates of dropout, sporadic dropins, different amounts of DNA from different contributors, relatedness of suspected and alternate contributors, "uncertain" allele designations, and degradation. R code implementing the method is open source, facilitating wide scrutiny. I illustrate its good performance using real cases and simulated crime scene profiles.