Weighting for DNA Profiling

AbstractDNA is present in most of the cells in our body, which is unique in each and every individual, and we leave a trail of it everywhere we go. This has become an advantage for forensic investigators who use DNA to draw conclusion in identification of victim and accused in crime scenes. This review describes the use of genetic markers in forensic investigation and their limitations.

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Proposed Framework for Comparison of Continuous Probabilistic Genotyping Systems amongst Different Laboratories

Forensic Sciences ◽

10.3390/forensicsci1010006 ◽

2021 ◽

Vol 1 (1) ◽

pp. 33-45

Author(s):

Dennis McNevin ◽

Kirsty Wright ◽

Mark Barash ◽

Sara Gomes ◽

Allan Jamieson ◽

...

Keyword(s):

Numerical Methods ◽

Analytical Solutions ◽

Peak Height ◽

Dna Profiling ◽

Likelihood Ratios ◽

Dna Mixtures ◽

Individual Laboratory ◽

Multiple Variables

Continuous probabilistic genotyping (PG) systems are becoming the default method for calculating likelihood ratios (LRs) for competing propositions about DNA mixtures. Calculation of the LR relies on numerical methods and simultaneous probabilistic simulations of multiple variables rather than on analytical solutions alone. Some also require modelling of individual laboratory processes that give rise to electropherogram artefacts and peak height variance. For these reasons, it has been argued that any LR produced by continuous PG is unique and cannot be compared with another. We challenge this assumption and demonstrate that there are a set of conditions defining specific DNA mixtures which can produce an aspirational LR and thereby provide a measure of reproducibility for DNA profiling systems incorporating PG. Such DNA mixtures could serve as the basis for inter-laboratory comparisons, even when different STR amplification kits are employed. We propose a procedure for an inter-laboratory comparison consistent with these conditions.

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Impact of poor evidence management on DNA profiling in sexual assault and homicide: A case report

Medico-Legal Journal ◽

10.1177/0025817220966487 ◽

2021 ◽

pp. 002581722096648

Author(s):

Naresh Kumar ◽

Pooja Puri ◽

SK Shukla ◽

Deepa Verma

Keyword(s):

Case Report ◽

Sexual Assault ◽

Dna Profiling ◽

Sexual Assaults ◽

Criminal Cases ◽

Her Family ◽

Female Victims ◽

Vaginal Swabs ◽

Biological Evidence

Increasing numbers of female victims of violent sexual assaults are being murdered with the aim of concealing the identity of the perpetrator. Proper handling and analysis of evidence is very important in gaining a conviction in many criminal cases. After evidence is collected, due precautions must be taken to ensure that the integrity of the sample is maintained, and chances of contamination are minimised. This paper presents a case study where improper handling of biological evidence led to loss of evidentiary value, and the semen could not be located on the vaginal swabs and victim’s garments due to improper preservation of samples. However, the DNA from the nail of a decomposed finger helped identify the victim, and the suspect was apprehended based on the clues given by her family.

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Assessment of QIAGEN™ Investigator® 24plex GO! kit workflow for autosomal STR profiling of forensic reference samples

Egyptian Journal of Forensic Sciences ◽

10.1186/s41935-020-00203-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Hashom Mohd Hakim ◽

Hussein Omar Khan ◽

Siti Afifah Ismail ◽

Nurul Hazirah Mat Lazim ◽

Japareng Lalung ◽

...

Keyword(s):

Pcr Amplification ◽

Dna Profiling ◽

Buccal Swab ◽

Forensic Dna ◽

Str Typing ◽

Str Analysis ◽

Dna Database ◽

Autosomal Str ◽

Dna Template ◽

Reference Samples

Abstract Background DNA profiling has proven to be a valuable technique for identification of individuals in crime. Currently, the technique targets several short tandem repeat (STR) regions in human genome. However, increasing number of samples submitted for STR analysis may lead to delays due to the limited number of experienced analysts who might be available at any given moment and the time taken to complete lengthy DNA profiling procedures. This study was conducted to test the specificity, repeatability, reproducibility and robustness of Investigator® 24plex GO! kit for genotyping of reference samples submitted to the Royal Malaysian Police Forensic DNA Laboratory for DNA database. Material and methods In this study, Investigator® 24plex GO! kit was used to directly amplify STR loci from buccal swab cell of reference samples that had previously been STR typed using GlobalFiler™ Express kit. Capillary electrophoresis was carried out on a 3500xL Genetic Analyser using POP-4® Polymer. Amplified products were assigned to particular STR alleles using the GeneMapper ID-X version 1.4 software. Results Our study shows that STR profiles generated using Investigator® 24plex GO! gave concordance results with those previously obtained using the GlobalFiler™ Express kit. In addition, quality sensors included in the kit are of particular importance for determining the effectiveness of the PCR reaction and help to indicate the nature and quantity of DNA template for PCR amplification. Conclusion The Investigator® 24plex GO! kit is reliable for STR typing of reference samples.

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