Forensic Genetics and Genotyping

Abstract Forensic genetics represents a combination of molecular and population genetics. Personal identification and kinship analysis (e.g. paternity testing) are the two main subjects of forensic DNA analysis. Biological specimens from which DNA is isolated are blood, semen, saliva, tissues, bones, teeth, hairs. Genotyping has become a basis in the characterization of forensic biological evidence. It is performed using a variety of genetic markers, which are divided into two large groups: bi-allelic (single-nucleotide polymorphisms, SNP) and multi-allelic polymorphisms (variable number of tandem repeats, VNTR and short tandem repeats, STR). This review describes the purpose of genetic markers in forensic investigation and their limitations. The STR loci are currently the most informative genetic markers for identity testing, but in cases without a suspect SNP can predict offender’s ancestry and phenotype traits such as skin, eyes and hair color. Nowadays, many countries worldwide have established forensic DNA databases based on autosomal short tandem repeats and other markers. In order for DNA profile database to be useful at a national or international level, it is essential to standardize genetic markers used in laboratories.

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Conditional Genotypic Probabilities for Microsatellite Loci

Genetics ◽

10.1093/genetics/155.4.1973 ◽

2000 ◽

Vol 155 (4) ◽

pp. 1973-1980

Author(s):

Jinko Graham ◽

James Curran ◽

B S Weir

Keyword(s):

Short Tandem Repeats ◽

Tandem Repeats ◽

Dirichlet Distribution ◽

Forensic Dna ◽

Match Probability ◽

Microsatellite Genotype ◽

Allelic State ◽

Forensic Assessments ◽

Dna Profiles ◽

Short Tandem

Abstract Modern forensic DNA profiles are constructed using microsatellites, short tandem repeats of 2–5 bases. In the absence of genetic data on a crime-specific subpopulation, one tool for evaluating profile evidence is the match probability. The match probability is the conditional probability that a random person would have the profile of interest given that the suspect has it and that these people are different members of the same subpopulation. One issue in evaluating the match probability is population differentiation, which can induce coancestry among subpopulation members. Forensic assessments that ignore coancestry typically overstate the strength of evidence against the suspect. Theory has been developed to account for coancestry; assumptions include a steady-state population and a mutation model in which the allelic state after a mutation event is independent of the prior state. Under these assumptions, the joint allelic probabilities within a subpopulation may be approximated by the moments of a Dirichlet distribution. We investigate the adequacy of this approximation for profiled loci that mutate according to a generalized stepwise model. Simulations suggest that the Dirichlet theory can still overstate the evidence against a suspect with a common microsatellite genotype. However, Dirichlet-based estimators were less biased than the product-rule estimator, which ignores coancestry.

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Personal Identification Using Y-Chromosomal Short Tandem Repeats From Bodily Fluids Mixed With Semen

American Journal of Forensic Medicine & Pathology ◽

10.1097/00000433-200109000-00018 ◽

2001 ◽

Vol 22 (3) ◽

pp. 288-291 ◽

Cited By ~ 11

Author(s):

Akiko Tsuji ◽

Atsushi Ishiko ◽

Noriaki Ikeda ◽

Hiroki Yamaguchi

Keyword(s):

Short Tandem Repeats ◽

Tandem Repeats ◽

Personal Identification ◽

Bodily Fluids ◽

Short Tandem

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Towards Development of Clustering Applications for Large-Scale Comparative Genotyping and Kinship Analysis Using Y-Short Tandem Repeats

OMICS A Journal of Integrative Biology ◽

10.1089/omi.2014.0136 ◽

2015 ◽

Vol 19 (6) ◽

pp. 361-367 ◽

Cited By ~ 3

Author(s):

Ali Seman ◽

Azizian Mohd Sapawi ◽

Mohd Zaki Salleh

Keyword(s):

Large Scale ◽

Short Tandem Repeats ◽

Tandem Repeats ◽

Kinship Analysis ◽

Short Tandem

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The Plateau Method for Forensic DNA SNP Mixture Deconvolution

10.1101/225805 ◽

2017 ◽

Cited By ~ 3

Author(s):

Darrell O. Ricke ◽

Joe Isaacson ◽

James Watkins ◽

Philip Fremont-Smith ◽

Tara Boettcher ◽

...

Keyword(s):

Short Tandem Repeats ◽

Tandem Repeats ◽

High Throughput Sequencing ◽

Nucleotide Polymorphisms ◽

Forensic Dna ◽

Dna Mixtures ◽

Single Nucleotide ◽

Mixture Deconvolution ◽

Dna Mixture ◽

Short Tandem

AbstractIdentification of individuals in complex DNA mixtures remains a challenge for forensic analysts. Recent advances in high throughput sequencing (HTS) are enabling analysis of DNA mixtures with expanded panels of Short Tandem Repeats (STRs) and/or Single Nucleotide Polymorphisms (SNPs). We present the plateau method for direct SNP DNA mixture deconvolution into sub-profiles based on differences in contributors’ DNA concentrations in the mixtures in the absence of matching reference profiles. The Plateau method can detect profiles of individuals whose contribution is as low as 1/200 in a DNA mixture (patent pending)1.

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Overview of Forensic DNA Profiling and Database

Khalij-Libya Journal of Dental and Medical Research ◽

10.47705/kjdmr.215105 ◽

2021 ◽

pp. 23-29

Author(s):

Sabreen Sabreen Aboujildah

Keyword(s):

Genetic Markers ◽

Tandem Repeats ◽

Forensic Genetics ◽

Human Leukocyte ◽

Dna Profiling ◽

Individual Identification ◽

Forensic Dna ◽

Forensic Dna Profiling ◽

Victims Of Violence ◽

Forensic Genetic

Deoxyribonucleic acid (DNA) profiling, has had a tremendous impact on forensic genetics. Before DNA profiling, all forensic genetic casework (e.g., Paternity testing, criminal casework, individual identification) was performed using classical serological genetic markers. Blood groups, human leukocyte antigen (HLA), and polymorphic protein and enzymes were used for solving forensic genetic casework using immunological and electrophoretic methodologies. These genetic markers were nevertheless limited when it was necessary to analyze minimal or degraded material, which is commonly involved in forensic cases. An STR is a region of human DNA containing an array of tandem repeats. Arrays range from only a 10 to about a hundred repeated units. This essay confers the basic concepts of operating of DNA in the criminal investigation. This review primarily summarizes the major tandem repeat markers used in forensic DNA profiling, that assist criminal’s conviction, exonerate the inferring individuals, and recognize victims of violence, catastrophes, and armed conflict.

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An Exploration of Mixed DNA Samples by Forensic Biological Data

International Journal of Natural Computing Research ◽

10.4018/ijncr.2020040101 ◽

2020 ◽

Vol 9 (2) ◽

pp. 1-13

Author(s):

Suvarna Vani Koneru ◽

Praveen Kumar Kollu ◽

Geethika Kodali ◽

Naveen Pothineni ◽

Sri Chaitanya Aravapalli

Keyword(s):

Short Tandem Repeats ◽

Tandem Repeats ◽

Biological Data ◽

Dna Profiling ◽

General Idea ◽

Dna Profile ◽

Bioinformatics Application ◽

Short Tandem

This article presents criminal bioinformatics approach which turned out to be fast, exact, and definitive in the evaluation and the investigation of crude DNA profiling information. The most problematic scenario for mixture interpretation, however, is when the amount of DNA is limited for one or more of the sources in a mixture. The present study has examined the utility of legal bioinformatics application to Short Tandem Repeats (STR) information. The DNA profiling information is overseen and investigated on the grounds of the different loci display and changeability in various people. The authors have consolidated a similar general idea Inconstancy in STR areas can be utilized to recognize one DNA profile from another.

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Evidence of partial and weak gametic disequilibrium across clusters of pericentromeric short tandem repeats loci on human X chromosome: Proceed with caution in forensic genetics

Forensic Science International Genetics ◽

10.1016/j.fsigen.2009.12.002 ◽

2011 ◽

Vol 5 (5) ◽

pp. 545-547 ◽

Cited By ~ 4

Author(s):

Enrique Medina-Acosta

Keyword(s):

X Chromosome ◽

Short Tandem Repeats ◽

Tandem Repeats ◽

Forensic Genetics ◽

Gametic Disequilibrium ◽

Short Tandem

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Animal Forensic Genetics

Genes ◽

10.3390/genes12040515 ◽

2021 ◽

Vol 12 (4) ◽

pp. 515

Author(s):

Adrian Linacre

Keyword(s):

Short Tandem Repeats ◽

Tandem Repeats ◽

Potential Role ◽

Forensic Genetics ◽

Human Species ◽

Domestic Species ◽

Traditional Medicines ◽

Increased Sensitivity ◽

Forensic Testing ◽

Short Tandem

Animal forensic genetics, where the focus is on non-human species, is broadly divided in two: domestic species and wildlife. When traces of a domestic species are relevant to a forensic investigation the question of species identification is less important, as the material comes from either a dog or a cat for instance, but more relevant may be the identification of the actual pet. Identification of a specific animal draws on similar methods to those used in human identification by using microsatellite markers. The use of cat short tandem repeats to link a cat hair to a particular cat paved the way for similar identification of dogs. Wildlife forensic science is becoming accepted as a recognised discipline. There is growing acceptance that the illegal trade in wildlife is having devasting effects on the numbers of iconic species. Loci on the mitochondrial genome are used to identify the most likely species present. Sequencing the whole locus may not be needed if specific bases can be targeted. There can be benefits of increased sensitivity using mitochondrial loci for species testing, but occasionally there is an issue if hybrids are present. The use of massively parallel DNA sequencing has a role in the identification of the ingredients of traditional medicines where studies found protected species to be present, and a potential role in future species assignments. Non-human animal forensic testing can play a key role in investigations provided that it is performed to the same standards as all other DNA profiling processes.

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