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Clinical Laboratory 2016Serological and biochemical identification methods used in forensics have several major disadvantages, such as: long time in processing biological sample and lack of... (Review)
Review
BACKGROUND
Serological and biochemical identification methods used in forensics have several major disadvantages, such as: long time in processing biological sample and lack of sensitivity and specificity. In the last 30 years, DNA molecular analysis has become an important tool in forensic investigations. DNA profiling is based on the short tandem repeats (STR) and aids in human identification from biological samples.
METHODS
Forensic genetics, can provide information on the events which occurred at the crime scene or to supplement other methods of forensic identification. Currently, the methods used in identification are based on polymerase chain reaction (PCR) analyses. This method analyses the autosomal STRs, the Y-chromosome, and the mitochondrial DNA.
RESULTS
Correlation of biological samples present at the crime scene with identification, selection, and the probative value factor is therefore the first aspect to be taken into consideration in the forensic genetic analysis.
CONCLUSIONS
In the last decade, because of the advances in the field of molecular biology, new biomarkers such as: microRNAs (miR), messenger RNA (mRNA), and DNA methylation have been studied and proposed to be used in the forensic identifications of body fluids.
Topics: Chromosomes, Human, Y; DNA Fingerprinting; DNA, Mitochondrial; Diffusion of Innovation; Genetic Markers; Humans; Microsatellite Repeats; Polymerase Chain Reaction; Polymorphism, Single Nucleotide; Predictive Value of Tests; Sequence Analysis, DNA
PubMed: 27012057
DOI: 10.7754/clin.lab.2015.150414 -
Gerontology 2018Forensic genetics developed from protein-based techniques a quarter of a century ago and became famous as "DNA fingerprinting," this being based on restriction fragment... (Review)
Review
Forensic genetics developed from protein-based techniques a quarter of a century ago and became famous as "DNA fingerprinting," this being based on restriction fragment length polymorphisms (RFLPs) of high-molecular-weight DNA. The amplification of much smaller short tandem repeat (STR) sequences using the polymerase chain reaction soon replaced RFLP analysis and advanced to become the gold standard in genetic identification. Meanwhile, STR multiplexes have been developed and made commercially available which simultaneously amplify up to 30 STR loci from as little as 15 cells or fewer. The enormous information content that comes with the large variety of observed STR genotypes allows for genetic individualisation (with the exception of identical twins). Carefully selected core STR loci form the basis of intelligence-led DNA databases that provide investigative leads by linking unsolved crime scenes and criminals through their matched STR profiles. Nevertheless, the success of modern DNA fingerprinting depends on the availability of reference material from suspects. In order to provide new investigative leads in cases where such reference samples are absent, forensic scientists started to explore the prediction of phenotypic traits from the DNA of the evidentiary sample. This paradigm change now uses DNA and epigenetic markers to forecast characteristics that are useful to triage further investigative work. So far, the best investigated externally visible characteristics are eye, hair and skin colour, as well as geographic ancestry and age. Information on the chronological age of a stain donor (or any sample donor) is elemental for forensic investigations in a number of aspects and has, therefore, been explored by researchers in some detail. Among different methodological approaches tested to date, the methylation-sensitive analysis of carefully selected DNA markers (CpG sites) has brought the most promising results by providing prediction accuracies of ±3-4 years, which can be comparable to, or even surpass those from, eyewitness reports. This mini-review puts recent developments in age estimation via (epi)genetic methods in the context of the requirements and goals of forensic genetics and highlights paths to follow in the future of forensic genomics.
Topics: Aging; CpG Islands; DNA Fingerprinting; Databases, Nucleic Acid; Epigenomics; Forensic Genetics; Humans; Microsatellite Repeats
PubMed: 29393215
DOI: 10.1159/000486239 -
Forensic Science International. Genetics Jul 2019DNA mixture interpretation can produce opposing conclusions by qualified forensic analysts, even within the same laboratory. The long-delayed publication of the National...
DNA mixture interpretation can produce opposing conclusions by qualified forensic analysts, even within the same laboratory. The long-delayed publication of the National Institutes of Standards and Technology (NIST) study of 109 North American crime laboratories in this journal demonstrates this most clearly. This latest study supports earlier work that shows common methods such as the Combined Probability of Inclusion (CPI) have wrongly included innocent people as contributors to DNA mixtures. The 2016 President's Council of Advisors on Science and Technology report concluded, "In summary, the interpretation of complex DNA mixtures with the CPI statistic has been an inadequately specified-and thus inappropriately subjective-method. As such, the method is clearly not foundationally valid" [7]. The adoption of probabilistic genotyping by many laboratories will certainly prevent some of these errors from occurring in the future, but the same laboratories that produced past errors can also now review old cases with their new software-without additional bench work. It is critical that laboratories adopt procedures and policies to do this.
Topics: DNA; DNA Fingerprinting; Forensic Genetics; Genotype; Government Agencies; Humans; Laboratories; Microsatellite Repeats; Probability; United States
PubMed: 30947116
DOI: 10.1016/j.fsigen.2019.03.005 -
Forensic Science International Aug 2019In forensic genetics, the analysis of DNA in biological samples is a valuable tool for personal identification. There is an increasing demand in analyzing of the mixed... (Review)
Review
In forensic genetics, the analysis of DNA in biological samples is a valuable tool for personal identification. There is an increasing demand in analyzing of the mixed DNA which may provide insightful investigative instructions. With the continuous effort for the improvement of individual identification, complicated mixed stains represent a growing fraction of the samples processed by forensic laboratories. Recent technological advances have enabled quantitative analysis of DNA mixture and emerging sequencing approaches to decipher the complicated DNA mixture. Here, we describe the use of different genetic markers, typing approaches and analytical methods in mixture analysis, and how useful information can be obtained from complicated DNA mixture.
Topics: DNA; DNA Fingerprinting; Forensic Genetics; Genetic Markers; Haplotypes; Humans; Likelihood Functions; Microsatellite Repeats; Polymorphism, Single Nucleotide; Sequence Analysis, DNA
PubMed: 31153987
DOI: 10.1016/j.forsciint.2019.05.024 -
Analytical Chemistry Jan 2019
Review
Topics: Animals; Body Fluids; DNA; DNA Fingerprinting; Forensic Genetics; Genotyping Techniques; Humans; Microbiota; RNA
PubMed: 30485738
DOI: 10.1021/acs.analchem.8b05318 -
Forensic Science International Jan 2021Since the discovery of Deoxyribonucleic acid (DNA) capability in forensic investigation, it has been an important part of the criminal justice system. In most criminal... (Review)
Review
Since the discovery of Deoxyribonucleic acid (DNA) capability in forensic investigation, it has been an important part of the criminal justice system. In most criminal cases DNA profile originating from evidence sample collected from the crime scene is compared with the DNA profile from the reference sample. However, when a reference sample is not available for comparison, familial DNA analysis can provide important investigation leads in a criminal investigation process by identifying an individual. Moreover, this analysis is also proving effective in the identification of ethnicity and ancestry of an individual. A number of different methodologies and software are being used for familial DNA analysis. This review describes the importance of familial DNA analysis, methodologies used for familial DNA searching and identification, and its advantages in forensic. Moreover, ethical, legal and social issues associated with familial DNA analysis have also been discussed along with future directions for the proper implementation of this technology.
Topics: Chromosomes, Human, Y; DNA Fingerprinting; DNA, Mitochondrial; Databases, Genetic; Forensic Genetics; Genetic Privacy; Genotype; Humans; Microsatellite Repeats; Pedigree; Polymorphism, Single Nucleotide; Racial Groups
PubMed: 33234348
DOI: 10.1016/j.forsciint.2020.110576 -
Genes Nov 2021Understanding the factors that may impact the transfer, persistence, prevalence and recovery of DNA (DNA-TPPR), and the availability of data to assign probabilities to... (Review)
Review
Understanding the factors that may impact the transfer, persistence, prevalence and recovery of DNA (DNA-TPPR), and the availability of data to assign probabilities to DNA quantities and profile types being obtained given particular scenarios and circumstances, is paramount when performing, and giving guidance on, evaluations of DNA findings given activity level propositions (activity level evaluations). In late 2018 and early 2019, three major reviews were published on aspects of DNA-TPPR, with each advocating the need for further research and other actions to support the conduct of DNA-related activity level evaluations. Here, we look at how challenges are being met, primarily by providing a synopsis of DNA-TPPR-related articles published since the conduct of these reviews and briefly exploring some of the actions taken by industry stakeholders towards addressing identified gaps. Much has been carried out in recent years, and efforts continue, to meet the challenges to continually improve the capacity of forensic experts to provide the guidance sought by the judiciary with respect to the transfer of DNA.
Topics: DNA; DNA Fingerprinting; Forensic Genetics; Humans; Specimen Handling
PubMed: 34828372
DOI: 10.3390/genes12111766 -
Annual Review of Genomics and Human... Aug 2020In the past few years, cases with DNA evidence that could not be solved with direct matches in DNA databases have benefited from comparing single-nucleotide polymorphism... (Review)
Review
In the past few years, cases with DNA evidence that could not be solved with direct matches in DNA databases have benefited from comparing single-nucleotide polymorphism data with private and public genomic databases. Using a combination of genome comparisons and traditional genealogical research, investigators can triangulate distant relatives to the contributor of DNA data from a crime scene, ultimately identifying perpetrators of violent crimes. This approach has also been successful in identifying unknown deceased persons and perpetrators of lesser crimes. Such advances are bringing into focus ethical questions on how much access to DNA databases should be granted to law enforcement and how best to empower public genome contributors with control over their data. The necessary policies will take time to develop but can be informed by reflection on the familial searching policies developed for searches of the federal DNA database and considerations of the anonymity and privacy interests of civilians.
Topics: Crime; DNA; DNA Fingerprinting; Databases, Nucleic Acid; Forensic Genetics; Humans; Pedigree
PubMed: 32289230
DOI: 10.1146/annurev-genom-111819-084213 -
International Journal of Molecular... Dec 2022Collection and interpretation of "touch DNA" from crime scenes represent crucial steps during criminal investigations, with clear consequences in courtrooms. Although... (Review)
Review
Collection and interpretation of "touch DNA" from crime scenes represent crucial steps during criminal investigations, with clear consequences in courtrooms. Although the main aspects of this type of evidence have been extensively studied, some controversial issues remain. For instance, there is no conclusive evidence indicating which sampling method results in the highest rate of biological material recovery. Thus, this study aimed to describe the actual considerations on touch DNA and to compare three different sampling procedures, which were "single-swab", "double-swab", and "other methods" (i.e., cutting out, adhesive tape, FTA paper scraping), based on the experimental results published in the recent literature. The data analysis performed shows the higher efficiency of the single-swab method in DNA recovery in a wide variety of experimental settings. On the contrary, the double-swab technique and other methods do not seem to improve recovery rates. Despite the apparent discrepancy with previous research, these results underline certain limitations inherent to the sampling procedures investigated. The application of this information to forensic investigations and laboratories could improve operative standard procedures and enhance this almost fundamental investigative tool's probative value.
Topics: Touch; DNA Fingerprinting; DNA; Specimen Handling
PubMed: 36555182
DOI: 10.3390/ijms232415541 -
Journal of Forensic Sciences Jan 2023Since Y-STR typing only amplifies male Y chromosomal DNA, it can simplify the interpretation of some DNA mixtures that contain female DNA. However, if there are multiple...
Since Y-STR typing only amplifies male Y chromosomal DNA, it can simplify the interpretation of some DNA mixtures that contain female DNA. However, if there are multiple male contributors, mixed Y-STR DNA profiles will often be obtained. Y-STR mixture analysis cases are particularly challenging though as, currently, there are no validated probabilistic genotyping (PG) software solutions commercially available to aid in their interpretation. One approach to fully deconvoluting these challenging mixtures into their individual donors is to conduct single-cell genotyping by isolating individual cells from a mixture prior to conducting DNA typing. In this work, a physical micromanipulation technique involving a tungsten needle and direct PCR with decreased reaction volume and increased cycle number was applied to equimolar 2- and 3-person buccal cell male DNA mixtures and a mock touch DNA case scenario involving the consecutive firing of a handgun by two males. A consensus DNA profiling approach was then utilized to obtain YFiler™ Plus Y-STR haplotypes. Buccal cells were used to optimize and test the direct single-cell subsampling approach, and 2-3 person male buccal cell mixtures were fully deconvoluted into their individual donor Y-STR haplotypes. Single-cell (or agglomerated cell clump) subsampling from the gun's trigger recovered single-source Y-STR profiles from both individuals who fired the gun, the owner, and the other unrelated male. Only the non-owner's DNA was found in the cells recovered from the handle. In summary, direct single-cell subsampling as described represents a potential simple way to analyze and interpret Y-STR mixtures.
Topics: Humans; Male; Female; Mouth Mucosa; Microsatellite Repeats; DNA Fingerprinting; Haplotypes; DNA; Single-Cell Analysis; Chromosomes, Human, Y
PubMed: 36183153
DOI: 10.1111/1556-4029.15150