Direct PCR amplification from saliva sample using non-direct multiplex STR kits for forensic DNA typing

Abstract

Due to its proficiency to provide the most discriminating results for forensic applications, medical research and anthropological studies, multiplex PCR based STR analysis has been established as the most efficient technique in the forensic DNA analysis. Several multiplex amplification kits based on 4, 5 and 6 dyes chemistry are commercially available and used in forensic DNA typing across the globe. These multiplex PCR systems are routinely used for amplification of multiple STR loci (Autosomal, Y and/or X STR’s) in the DNA extracted from various biological samples. In the routine forensic DNA testing, DNA profile obtained is compared with the DNA profile of the reference sample, which takes a certain turnaround time and employs costly lab resources. Successive development in forensic DNA typing have resulted in advent of improved multiplex kits which have reduced the effective analysis time, cost and minimized the number of steps required in comparison to conventional forensic DNA typing. Specialized direct amplification compatible multiplex kits are also available nowadays. These kits are relatively costlier but still require few pre-processing steps, which does not make them worth the hefty cost. Herein, this study, we have used non-direct multiplex STR kits to assess their efficacy for direct amplification. In the present study, 103 saliva samples were directly amplified without any pre-treatment of the samples using thirteen non-direct multiplex kits (4 dyes, 5 dyes and 6 dyes chemistry based) for forensic DNA typing. Here, we report a validated direct PCR amplification protocol from the reference saliva samples by omitting DNA extraction and quantification steps, which resulted in 80% reduction of the turnaround time. The developed protocol is cost effective, time efficient and it does not compromise with the quality of DNA profiles. To the best of our knowledge, this is the first report for direct amplification of DNA with the most commonly used non-direct multiplex STR kits without any pre-treatment of the sample. Complete DNA profiles matching all the essential quality parameters were obtained successfully from all the tested samples.

Internal validation of reduced PCR reaction volume of the Qiagen Investigator® Argus X‐12 QS Kit from blood samples on FTA cards

“…Furthermore, none of the samples had the PHR < 0.7, supporting the indication by Butler [19] that balance heterozygotes prevailed between the two alleles. Similar findings are reported by Shrivastava et al [8] when they optimized the direct amplification of X‐STRs from saliva samples using the reduced PCR reaction volume of Qiagen Investigator® Argus X‐12 QS Kit. Nonetheless, similar optimization work involving the 60% reduction in PCR reaction volume for the same kit for purified blood samples remains unreported, and hence, suitable comparison with the findings reported here could not be made.…”

Genetic individual identification from dried urine spots: A complementary tool to drug monitoring and anti‐doping testing

“…The genetic profiles were achieved through direct PCR amplification of STR markers contained in a validated forensic commercial kit 47 . Direct PCR avoids the time‐consuming and costly procedures of DNA extraction and molecular quantification; in addition, this procedure prevents the loss of the valuable DNA, which can be very limited in these kinds of stains.…”

A Study on DNA Profiling Techniques and Transnational Exchange of DNA Data from Databank

“…The model performance is measured and evaluated by using the Receiver Operator Characteristics (ROC) plots [55,56]. These graphs illustrate the rates of false-negative and falsepositive support with the observed LR (Figure 7).…”