Qiagen's Investigator™ Quantiplex Kit as a Predictor of STR Amplification Success from Low‐Yield DNA Samples^,

Abstract

Qiagen's Investigator™ Quantiplex kit, a total human DNA quantitation kit, has a 200-base pair internal control, fast cycling time, and scorpion molecules containing a covalently linked primer, probe, fluorophore, and quencher. The Investigator™ Quantiplex kit was evaluated to investigate a value under which complete short tandem repeat (STR) failure was consistently obtained. Buccal swabs were extracted using the Qiagen QIAamp(®) DNA Blood Mini Kit, quantified with the Investigator™ Quantiplex kit using a tested half-volume reaction, amplified with the ABI AmpFlSTR(®) Identifiler kit, separated on the 3100Avant Genetic Analyzer, and data analyzed with GeneMapper(®) ID v.3.2. While undetected samples were unlikely to produce sufficient data for statistical calculations or CODIS upload (2.00 alleles and 0.82 complete loci on average), data may be useful for exclusionary purposes. Thus, the Investigator™ Quantiplex kit may be useful for predicting STR success. These findings are comparable with previously reported data from the Quantifiler™ Human kit.

The effects of metal ion PCR inhibitors on results obtained with the Quantifiler ® Human DNA Quantification Kit

“…Each system includes a human-specific probe that targets an evolutionarily conserved region of the human genome. While the physical design varies between manufacturers, these probes contain a fluorescent reporter dye whose fluorescence is altered as a consequence of target amplification and allow the amount of emitted fluorescent signal to be detected during each PCR cycle [4][5][6]. All qPCR-based quantification methods compare the fluorescent signal measured in a sample to a passive reference signal; this is a fluorescent component that does not change as a result of cycles of PCR.…”

“…Anything that changes the PCR conditions, such as the availability of reagents, pH or salt concentration, DNA polymerase function, or access to the DNA template, can impact the accuracy of the results [10]. Assessment of the individual quantification reactions and detection of substances that can inhibit PCR is aided by the inclusion of an internal PCR control (IPC) in each of the aforementioned quantification systems [4][5][6].…”

Advances in forensic DNA quantification: A review

“…Another duplex multiplex developed was the Investigator Quantiplex™, a procedure that targets a 4NS1C gene at 146 bp along with an IPC of 200 bp . Since the 4NS1C is a multicopy gene, the assay produced detection limits below 4.9 pg/μL.…”

Screening Sexual Assault Evidence with Low Concentrations of Male DNA Utilizing the RapidHIT 200 and ParaDNA Intelligence Test

“…c, n, m), illustrating the progression of the process. The user can further evaluate this illustration by assessing the four primary stages: Lag, Exponential, Linear, and Plateau to ensure proper amplification has occurred [23]. The exponential phase, however, is the most significant out of the four stages because PCR amplification should achieve optimal efficiency (E and " ) and produce a copious amount of amplified product.…”

“…The exponential phase, however, is the most significant out of the four stages because PCR amplification should achieve optimal efficiency (E and " ) and produce a copious amount of amplified product. Therefore, enabling the concentration of amplified product ( $ ) to be used to calculate the initial concentration of template DNA (N), using equation one [22,23]. The threshold cycle ( & ) can then be computed (equation 2) to create a baseline that when reached demonstrates an increase in signal intensity of a target molecule at a given cycle ( ( -) above the software's internal baseline [22,23].…”