Abstract
Short repetitive regions in autosomal and Y chromosomes known as short tandem repeats (STRs) are currently used for DNA profiling in crime investigations. However, DNA profiling requires a sufficient quality and quantity of DNA template, which is often not obtained from trace evidence or degraded biological samples collected at the scene of a crime. Here, we assessed autosomal and male DNA components extracted from crime scene and mock casework samples using the Casework Direct Kit, Custom and compared the results against those obtained by extraction of matching samples using well-established Maxwell 16 System DNA IQ Casework Pro Kit. The quantity and quality of extracted DNA obtained using both Casework Direct Kit, Custom and Maxwell 16 System DNA IQ Casework Pro Kit were analyzed using PowerQuant Systems followed by autosomal and Y-chromosome STR profiling using GlobalFiler Express PCR Amplification Kit and PowerPlex Y23 System, respectively. Our results showed that the Casework Direct Kit and Maxwell 16 DNA IQ Casework Pro Kit have more or less equal capacity to extract inhibitor free DNA, but that the latter produces slightly better quality and more DNA template and subsequently higher numbers of STR allele calls for autosomal and Y-STR analyses. Nonetheless, the Casework Direct Kit, Custom is the quicker and cheaper option for extraction of good, clean DNA from high content material and might best be used for extraction of reference samples. Such reference DNA samples typically come from buccal swabs or freshly drawn blood. So, in general, they can confidently be expected to have a high nucleic acid content and to be inhibitor-free.
Highlights
Www.nature.com/scientificreports criminal investigations due to limited number of experienced analysts who may be available together with queues due to prolonged sample screening and processing time[1]
Only a few of the DNA templates extracted from the crime scene and mock casework samples using Maxwell 16 System DNA IQ Kit or Casework Direct Kit, Custom exceeded the require threshold values for reliable autosomal and Y chromosome short tandem repeats (STRs) profiling using Globalfiler Express and PowerPlex Y23
Full autosomal (6 versus 4) and Y chromosome (6 versus 0) STR allele calls were higher for DNA templates extracted using Maxwell 16 System DNA IQ Kit than using Casework Direct Kit, Custom (Figs 3 and 4 and refer Table 1 for average percentage of allele calling for autosomal and Y chromosome STR)
Summary
Www.nature.com/scientificreports criminal investigations due to limited number of experienced analysts who may be available together with queues due to prolonged sample screening and processing time[1]. A modern forensic DNA service should be equipped with a reliable machine platform capable of avoiding human errors, reducing crossover contamination, and improving turnaround time These requirements have led to the development of rapid automated platforms for DNA extraction, amplification[2,3,4] and quantitation[5,6,7,8,9,10,11]. Promega Corporation has developed a new system, the Casework Direct Kit, Custom that does not need repeated washing steps in extracting the nucleic acids It contains only casework extraction buffer and a reducing agent, 1-thioglycerol, a combination that is designed to rapidly produce DNA lysate from casework samples. The quantity and quality of extracted DNA obtained using both Casework Direct Kit, Custom and Maxwell 16 System DNA IQ Casework Pro Kit were compared and analyzed using PowerQuant Systems (Promega Corporation, Madison, USA) followed by autosomal and Y-chromosome STR profiling using GlobalFiler Express PCR Amplification Kit (Applied Biosystem) and PowerPlex Y23 System (Promega Corporation, Madison, USA), respectively
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