The German Stain Commission: recommendations for the interpretation of mixed stains

Schneider, P. M.; Fimmers, Rolf; Keil, W.; Molsberger, G.; Patzelt, D.; Pflug, Werner; Rothämel, Thomas; Schmitter, H.; Schneider, H.; Brinkmann, B.

doi:10.1007/s00414-008-0244-4

Cited by 52 publications

(24 citation statements)

References 4 publications

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“…In such circumstances, a significant peak height imbalance at a locus where only two alleles are observed may still be indicative of a mixed sample [15][16][17][18][19][20][21]. Peak height information is less reliable with low quantities of DNA template mainly due to modifications to the testing process and PCR sampling issues.…”

Section: Discussionmentioning

confidence: 95%

“…Not all mixtures of two or more individuals exhibit three or more peaks at every locus, particularly when information is only available at a small number of loci such as often occurs with samples containing small amounts of template DNA and/or those that are degraded and/or inhibited [13][14][15][16][17][18][19][20][21]. In such circumstances, a significant peak height imbalance at a locus where only two alleles are observed may still be indicative of a mixed sample [15][16][17][18][19][20][21].…”

Section: Discussionmentioning

confidence: 99%

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

Gilder¹,

Inman

Shields

et al. 2010

Int J Legal Med

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When the smaller of two peaks at an STR locus is less than 70% the magnitude of the larger peak at that locus, the disparity is typically taken to be an indication that there is more than one contributor of template DNA to the sample being tested. An analysis of 1,763 heterozygous allele pairs suggests that a peak height imbalance threshold that varies with the magnitude of the peaks being evaluated at a locus is superior to a fixed threshold. Identifying samples that are likely to be mixtures and those that are likely to have arisen from a single source is accomplished more reliably when a statistically based, magnitude-dependent peak height imbalance threshold is used. The amelogenin locus was found to behave in a similar fashion and was also found to have no systematic bias that favored the amplification of Y or X alleles.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

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

Gilder¹,

Inman

Shields

et al. 2010

Int J Legal Med

View full text Add to dashboard Cite

show abstract

“…In this context, previous studies suggest that optimal range for a mixture analysis can be anywhere between 50%, with equal amounts of both contributors (type A mixture), and 20%, with a major and a minor contributor (type B mixture) (Table ) . With less than 20% for the minor contributor, allele dropout may occur or a true peak may be considered a stutter .…”

Section: Resultsmentioning

confidence: 99%

The Use of Laser Microdissection in Forensic Sexual Assault Casework: Pros and Cons Compared to Standard Methods

Costa

Correia-de-Sá

Porto

et al. 2017

Journal of Forensic Sciences

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Sexual assault samples are among the most frequently analyzed in a forensic laboratory. These account for almost half of all samples processed routinely, and a large portion of these cases remain unsolved. These samples often pose problems to traditional analytic methods of identification because they consist most frequently of cell mixtures from at least two contributors: the victim (usually female) and the perpetrator (usually male). In this study, we propose the use of current preliminary testing for sperm detection in order to determine the chances of success when faced with samples which can be good candidates to undergo analysis with the laser microdissection technology. Also, we used laser microdissection technology to capture fluorescently stained cells of interest differentiated by gender. Collected materials were then used for DNA genotyping with commercially available amplification kits such as Minifiler, Identifiler Plus, NGM, and Y-Filer. Both the methodology and the quality of the results were evaluated to assess the pros and cons of laser microdissection compared with standard methods. Overall, the combination of fluorescent staining combined with the Minifiler amplification kit provided the best results for autosomal markers, whereas the Y-Filer kit returned the expected results regardless of the used method.

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“…Schneider et al (2009) distinguish between three types of mixtures, with type A assumed to display all of the contributors' alleles above the threshold, type B showing clear major and minor components, and type C potentially being affected by stochastic effects and allelic drop out. Figure 63.5 shows examples for these three types of mixtures.…”

Section: Str Data Analysismentioning

confidence: 99%