Validation and development of interpretation guidelines for low copy number (LCN) DNA profiling in New Zealand using the AmpFlSTR® SGM Plus™ multiplex

Forensic genetic SNP typing of low-template DNA and highly degraded DNA from crime case samples

“…The four allele drop-ins were reexamined, but it was not possible to deduce whether the drop-ins were caused by a contamination or unusual high background noise in the electropherograms. The low drop-in rate of the sensitized SNPforID assay is in sharp contrast to the sensitized STR assays, where the drop-in rate may be 100 times higher [10][11][12][13][14][15][16][17][18]. Allele drop-ins are very problematic, because they may lead to false inclusions as well as false exclusions.…”

The influence of high temperature on the possibility of DNA typing in various human tissues

“…The first tactic was based on the analysis of STR (Short Tandem Repeats) and miniSTR loci amplification and, in the case of a negative outcome, mtDNA sequencing was performed. The study was performed using the commercially available STR and miniSTR kits: AmpFlSTR ® SGM Plus ® and AmpFlSTR ® MiniFiler TM [7,[19][20][21][22]. Amplification of hyper variable region I (HVI) of human mitochondrial DNA (mtDNA) was used [2,4,23] when STR and miniSTR typings gave negative results.…”

“…As a result of the high temperature exposure, the DNA available for analysis is highly thermally degraded and frequently present in very few copies. A trace amount of template DNA available for amplification very frequently leads to different types of artifacts such as a lack of amplification of particular alleles (allele drop-out) or loci (loci drop-out) [7][8][9][10]. The problem of the effect of high temperature on biological material and the possibility of DNA identification has been rarely mentioned.…”

Avoiding Errors and Pitfalls in Evidence Sampling for Forensic Genetics

“…To increase the detection of amplified product , methods have been developed to purify the PCR amplicons, to remove salts, ions and unused dNTPs and primers from the reaction by using filtration (Microcon filter columns), silica gel membranes (Quiagen MinElute) or enzyme hydrolysis (ExoSAP-IT) (Forster et al, 2008;Petricevic et al, 2010;Smith and Ballantyne, 2007)). This purification step is performed to remove negative ions such as Clwhich prevents inter-molecular competition occurring during electrokinetic injection allowing a maximum amount of DNA to be injected into the capillary of the sequencer.…”