Magnitude-dependent variation in peak height balance at heterozygous STR loci

Gilder, Jason R.; Inman, Keith; Shields, William M.; Krane, Dan E.

doi:10.1007/s00414-009-0411-2

Cited by 23 publications

(7 citation statements)

References 17 publications

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“…This parameter is accepted as a standard marker for the presence of male DNA in mixed samples as well as a parameter representing the level of male DNA in male/female mixtures [17]. In our samples, the Y/X ratio varied between 0% and 63%, which is in concordance with results of estimation of this ratio in pure male DNA samples, where it was found to vary between 80% and 136% [18]. After analysing the possible association of success of a-STR analysis (represented by CIOA/ CPIOA ratio) and the level of male DNA identified in salivary samples (represented by Y/X ratio), we were able to identify the association of the Y/X ratio and the outcome of a-STR profiling.…”

Section: Discussionsupporting

confidence: 77%

The Applicability of Autosomal Short Tandem Repeats Genotyping for Minor Contributor DNA Profiling from Mixed Saliva Samples

Repiská¹,

Durdiaková²,

Kamodyová³

et al. 2014

J Forensic

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Section: Discussionsupporting

confidence: 77%

The Applicability of Autosomal Short Tandem Repeats Genotyping for Minor Contributor DNA Profiling from Mixed Saliva Samples

Repiská¹,

Durdiaková²,

Kamodyová³

et al. 2014

J Forensic

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“…As DNA template levels are reduced, a concomitant drop in peak height and the mean PHR with increasing standard deviation (SD) was observed and is a previously documented phenomenon [14][15][16][17][18]. PHR increased at the lower template levels with both the SGM+ and ESI 16 results and is attributed to stochastic effects of DNA sampling and amplification.…”

Section: Discussionmentioning

confidence: 67%

Forensic validation of the PowerPlex® ESI 16 STR Multiplex and comparison of performance with AmpFlSTR® SGM Plus®

2011

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We describe the forensic validation of Promega's PowerPlex® European Standard Investigator 16 (ESI 16) multiplex kit and compare results generated with the AmpFlSTR® SGM Plus® (SGM+) multiplex. ESI 16 combines the loci contained within the SGM+ multiplex with five additional loci: D2S441, D10S1248, D22S1045, D1S1656, and D12S391. A relative reduction in amplicon size of the SGM+ loci facilitates an increased robustness and amplification success of these amplicons with degraded DNA samples. Tests performed herein supplement ESI 16 data published previously with sensitivity, profile quality, mock casework, inhibitor and mixture study data collected in our laboratories in alignment with our internal technical and quality guidelines and those issued by the Scientific Working Group on DNA Analysis Methods (SWGDAM), the DNA Advisory Board (DAB) and the DNA working group (DNAWG) of the European Network of Forensic Science Institutes (ENFSI). Full profiles were routinely generated from a fully heterozygous single source DNA template using 62.5 pg for ESI 16 and 500 pg for SGM+. This increase in sensitivity has a consequent effect on mixture analyses and the detection of minor mixture components. The improved PCR chemistry confers enhanced tolerance to high levels of laboratory prepared inhibitors compared with SGM+ results. In summary, our results demonstrate that the ESI 16 multiplex kit is more robust and sensitive compared with SGM+ and will be a suitable replacement system for the analysis of forensic DNA samples providing compliance with the European standard set of STR loci.

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“…The mixed DNA profiles are further complicated by the effects of stutter-affected heterozygotes (SAH) and allele masking, which leads to considerably more complex H b regularity. Mixed DNA samples involving very small or degenerated samples are particularly prone to distortion by random effects associated with the mutual inhibition of PCR invariant DNA components, distortion of the peak balance in the PCR system, operational issues and equipment errors (10,36,37). These factors significantly increase the difficulty of scientific analysis and the interpretation of accurate results obtained from mixed DNA profiles.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of parameters in mixed male DNA profiles for the Identifiler® multiplex system

Cong

Gao

et al. 2014

International Journal of Molecular Medicine

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The analysis of complex DNA mixtures is challenging for forensic DNA testing. Accurate and sensitive methods for profiling these samples are urgently required. In this study, we developed 11 groups of mixed male DNA samples (n=297) with scientific validation of D-value [>95% of D-values ≤0.1 with average peak height (APH) of the active alleles ≤2,500 rfu]. A strong linear correlation was detected between the peak height (PH) and peak area (PA) in the curve fit using the least squares method (P<2e-16). The Kruskal-Wallis rank-sum test revealed significant differences in the heterozygote balance ratio (Hb) at 16 short tandem repeat (STR) loci (P=0.0063) and 9 mixed gradients (P=0.02257). Locally weighted regression fitting of APH and Hb (inflection point at APH = 1,250 rfu) showed 92.74% of Hb >0.6 with the APH ≥1,250. The variation of Hb distribution in the different STR loci suggested the different forensic efficiencies of these loci. Allelic drop-out (ADO) correlated with the APH and mixed gradient. All ADOs had an APH of <1,000 rfu, and the number of ADO increased when the APH of mixed DNA profiles gradually decreased. These results strongly suggest that calibration parameters should be introduced to correct the deviation in the APH at each STR locus during the analysis of mixed DNA samples.

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Magnitude-dependent variation in peak height balance at heterozygous STR loci

Cited by 23 publications

References 17 publications

The Applicability of Autosomal Short Tandem Repeats Genotyping for Minor Contributor DNA Profiling from Mixed Saliva Samples

The Applicability of Autosomal Short Tandem Repeats Genotyping for Minor Contributor DNA Profiling from Mixed Saliva Samples

Forensic validation of the PowerPlex® ESI 16 STR Multiplex and comparison of performance with AmpFlSTR® SGM Plus®

Evaluation of parameters in mixed male DNA profiles for the Identifiler® multiplex system

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