scholarly journals Mutation Rate at Commonly Used Forensic STR Loci: Paternity Testing Experience

2004 ◽  
Vol 20 (6) ◽  
pp. 313-315 ◽  
Author(s):  
Faruk Aşıcıoğlua ◽  
Fatma Oguz-Savran ◽  
Ugur Ozbek
Keyword(s):  
Mutation Rate ◽  
Microsatellite Loci ◽  
Genetic Profile ◽  
Forensic Dna ◽  
Str Loci ◽  
Repeat Dna ◽  
Genetic Profiles ◽  
Paternity Tests ◽  
Forensic Dna Testing ◽  
Short Tandem

Paternity tests are carried out by the analysis of hypervariable short tandem repeat DNA loci. These microsatellite sequences mutate at a higher rate than that of bulk DNA. The occurrence of germline mutations at STR loci posses problems in interpretation of resulting genetic profiles. We recently analyzed 59–159 parent/child allele transfers at 13 microsatellite loci. We identified 12 mutations in 7 microsatellite loci. No mutations were occurred in other 6 loci. The highest mutation rate was observed with 5 mutations at D8S1179 locus at different alleles. The event was always single repeat related. The mutation rate was between 0 and 1.5 x 10-2per locus per gamete per generation. The mutation event is very crucial for forensic DNA testing and accumulation of STR mutation data is extremely important for genetic profile interpretation.

scholarly journals Costal cartilage ensures low degradation of DNA needed for genetic identification of human remains retrieved at different decomposition stages and different postmortem intervals

2021 ◽  
Vol 75 (1) ◽  
pp. 852-858
Author(s):  
Marcin Tomsia ◽  
Kornelia Droździok ◽  
Gulnaz T. Javan ◽  
Rafał Skowronek ◽  
Michał Szczepański ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Costal Cartilage ◽  
Dna Typing ◽  
Genetic Identification ◽  
Individual Identification ◽  
Genetic Profile ◽  
Forensic Dna ◽  
Autosomal Chromosome ◽  
Str Loci ◽  
Significant Difference

Abstract Introduction The study aimed to evaluate if costal cartilage is a good source of DNA for genetic individual identification tests performed in forensic autopsies. Materials and Methods The study included samples of costal cartilage collected from 80 cadavers retrieved from different environments: indoors (flat/hospital), outdoors (primarily in the forest), a coal mine, a fire site, uninhabited buildings, a basement, bodies of fresh water, exhumation sites, and unknown locations. After isolation of DNA chondrocytes, T. Large autosomal chromosome (214 bp), T. Small autosomal chromosome (80 bp), and the Y chromosome (75 bp; for male cadavers), sequences were amplified using real-time PCR. Additionally, 23 autosomal short tandem repeat (STR) loci and 16 Y chromosome STR loci were amplified using multiplex PCR. Forensic DNA typing was done using capillary electrophoresis and all results were analyzed. Results There was no statistically significant difference in DNA concentration after T. Large, T. Small autosomal chromosome and the Y chromosome amplification between samples collected from cadavers retrieved from different environments. The DNA degradation index was the same regardless of the postmortem interval. The results show that it is possible to generate a full genetic profile from costal cartilage samples collected from cadavers retrieved from different environments and at different times elapsed after death. Conclusions The results suggest that costal cartilage can be routinely collected during forensic autopsies, especially from cadavers at the advanced decomposition stage.

Incorrect opinions in disputed paternity cases – causes of discrepancies. A case report

2016 ◽  
Vol 294 ◽  
pp. 59-65
Author(s):  
Kornelia Droździok ◽  
◽  
Jadwiga Kabiesz ◽  
Marcin Tomsia ◽  
◽  
...  
Keyword(s):  
Case Report ◽  
Forensic Genetics ◽  
Genetic Profile ◽  
Great Role ◽  
Str Loci ◽  
Autosomal Str ◽  
The People ◽  
Genetic Profiles ◽  
Paternity Cases

In the report we have presented cases where false opinions concerning disputed paternity and blood relationship establishment were issued. In case 1a wrong assumption resulted in a false opinion in which paternity was excluded. The genetic profile of the child’s deceased defendant father was generated from genetic profiles of the child’s grandparents. In the issued opinion it was concluded that the deceased is not the child’s father. Based on analysis of grandparents’ genetic profiles we can only conclude that the child is not their grandchild. In disputed paternity cases where DNA from the child’s relatives (grandparents, siblings etc.) but not its parents is examined, many autosomal STR loci should be determined and if needed, STR loci on chromosome Y and X. Moreover, statistical analysis should be carried out. In case 2 the opinion was issued based on the fact that there were no excluding traits between defended relatives. In case 3 sampling was not done according to the proceedings, which did not allow to establish whether the sent samples were from the people mentioned in the protocol and finally a false opinion was issued. The report confirms a great role of a forensic genetics expert in issuing a true opinion concerning disputed paternity or blood relationship.

scholarly journals FastID: Extremely Fast Forensic DNA Comparisons

2017 ◽  
Author(s):  
Darrell O. Ricke
Keyword(s):  
Massively Parallel Sequencing ◽  
Forensic Analysis ◽  
Massively Parallel ◽  
Forensic Dna ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Str Loci ◽  
Forensic Samples ◽  
Scalable Analysis ◽  
Short Tandem

AbstractRapid analysis of DNA forensic samples can have a critical impact on time sensitive investigations. Analysis of forensic DNA samples by massively parallel sequencing is creating the next gold standard for DNA forensic analysis. This technology enables the expansion of forensic profiles from the current 20 short tandem repeat (STR) loci to tens of thousands of single nucleotide polymorphism (SNP) loci. A forensic search scales by the product of the number of loci and the number of profile comparisons. This paper introduces a method (FastID) to address the need for rapid scalable analysis of DNA forensic samples (patent pending)[1]. FastID can search a profile of 2,500 SNP loci against 20 million profiles in 5.08 seconds using a single computational thread on a laptop (Intel i7 4.0 GHz).

scholarly journals Crime Scene Analysis Through DNA Testing of Canine Feces—A Case Report

2020 ◽  
Vol 10 (1) ◽  
pp. 56-61
Author(s):  
Vishal Somnay ◽  
Thomas Duong ◽  
Ray-Young Tsao ◽  
Joseph A. Prahlow
Keyword(s):  
Case Report ◽  
Epithelial Cells ◽  
Critical Role ◽  
Crime Scene ◽  
Scene Analysis ◽  
Dna Testing ◽  
Forensic Dna ◽  
Forensic Dna Testing ◽  
Positive Results ◽  
Crime Scene Analysis

Forensic DNA testing can play a critical role in homicide investigations. Selecting the appropriate evidence on which to perform DNA testing requires foresight and reasoning based on experience and science. Although successful DNA testing can occur using many substrates, including blood, hair, and sweat/epithelial cells, positive results can also result from testing various unorthodox samples. The authors report on a triple-murder investigation where DNA testing of dog feces at the crime scene matched DNA testing of feces found on the shoe of a suspect resulting in successful prosecution of the case.

Conditional Genotypic Probabilities for Microsatellite Loci

Genetics ◽  
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.

scholarly journals Comparison of the Allelic Alterations between InDel and STR Markers in Tumoral Tissues Used for Forensic Purposes

Medicina ◽  
2021 ◽  
Vol 57 (3) ◽  
pp. 226
Author(s):  
Pamela Tozzo ◽  
Arianna Delicati ◽  
Anna Chiara Frigo ◽  
Luciana Caenazzo
Keyword(s):  
Colorectal Cancer ◽  
Genomic Instability ◽  
Tandem Repeats ◽  
Forensic Genetics ◽  
Tumor Type ◽  
Forensic Dna ◽  
Dna Identification ◽  
Human Dna ◽  
Tumor Transformation ◽  
Paternity Tests

Background and objectives: Over the last two decades, human DNA identification and kinship tests have been conducted mainly through the analysis of short tandem repeats (STRs). However, other types of markers, such as insertion/deletion polymorphisms (InDels), may be required when DNA is highly degraded. In forensic genetics, tumor samples may sometimes be used in some cases of human DNA identification and in paternity tests. Nevertheless, tumor genomic instability related to forensic DNA markers should be considered in forensic analyses since it can compromise genotype attribution. Therefore, it is useful to know what impact tumor transformation may have on the forensic interpretation of the results obtained from the analysis of these polymorphisms. Materials and Methods: The aim of this study was to investigate the genomic instability of InDels and STRs through the analysis of 55 markers in healthy tissue and tumor samples (hepatic, gastric, breast, and colorectal cancer) in 66 patients. The evaluation of genomic instability was performed comparing InDel and STR genotypes of tumor samples with those of their healthy counterparts. Results: With regard to STRs, colorectal cancer was found to be the tumor type affected by the highest number of mutations, whereas in the case of InDels the amount of genetic mutations turned out to be independent of the tumor type. However, the phenomena of genomic instability, such as loss of heterozygosity (LOH) and microsatellite instability (MSI), seem to affect InDels more than STRs hampering genotype attribution. Conclusion: We suggest that the use of STRs rather than InDels could be more suitable in forensic genotyping analyses given that InDels seem to be more affected than STRs by mutation events capable of compromising genotype attribution.

scholarly journals The Landscape of Human STR Variation

2014 ◽  
Author(s):  
Thomas F. Willems ◽  
Melissa Gymrek ◽  
Gareth Highnam ◽  
The Genomes Project ◽  
David Mittelman ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Phase 1 ◽  
Genetic Diseases ◽  
Point Mutations ◽  
Graphical Interface ◽  
Loss Of Function ◽  
Human Reference Genome ◽  
Str Loci ◽  
Classical Point ◽  
Short Tandem

Short Tandem Repeats are among the most polymorphic loci in the human genome. These loci play a role in the etiology of a range of genetic diseases and have been frequently utilized in forensics, population genetics, and genetic genealogy. Despite this plethora of applications, little is known about the variation of most STRs in the human population. Here, we report the largest-scale analysis of human STR variation to date. We collected information for nearly 700,000 STR loci across over 1,000 individuals in phase 1 of the 1000 Genomes Project. This process nearly saturated common STR variations. After employing a series of quality controls, we utilize this call set to analyze determinants of STR variation, assess the human reference genome?s representation of STR alleles, find STR loci with common loss-of-function alleles, and obtain initial estimates of the linkage disequilibrium between STRs and common SNPs. Overall, these analyses further elucidate the scale of genetic variation beyond classical point mutations. The resource is publicly available at http://strcat.teamerlich.org/ both in raw format and via a graphical interface. 

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