We’re excited to share some details on our newest 8-dye PowerPlex® kit, which will be available later this year. The 8-dye PowerPlex® 18E System combines all the ENFSI recommended loci, and Amelogenin and DYS391 are included for sex determination. The PowerPlex® 18E System is designed for human identification applications including forensic analysis and relationship testing. The kit can be used for both casework and database samples, simplifying workflows. As with all our PowerPlex® Systems, the PowerPlex® 18E System enables half volume direct amplification reactions with buccal swabs and blood and buccal samples on lytic and nonlytic storage card punches. Moreover, the use of 8 colors enables 15 autosomal STR loci to be present as amplicons under 250bp, making it ideal for use with degraded samples often seen in missing persons cases or mass disasters.
Figure 1: Configuration of the PowerPlex® 18E System. PowerPlex® 18E System meets the ENFSI recommendations for DNA profile sharing across Europe and allows co-amplification and detection of D3S1358, D8S1179, D18S51, D21S11, DYS391, FGA, TH01, vWA, D2S441, D10S1248, D22S1045, D1S1656, D12S391, D2S1338, D16S539, D19S433, SE33 and Amelogenin.
Figure 2: Amplifying Extracted DNA with the PowerPlex® 18E System. 1ng 2800M Control DNA was amplified for 29 cycles in 25µl reaction. Electrophoresis was performed on the Spectrum CE System. Data was analyzed using GeneMarker® HID Software for Spectrum CE Systems.
More Information from Your Samples
With current caseloads increasing, no one wants to have to repeat their STR analyses on DNA samples that failed to yield a full profile due to the presence of inhibitors or degradation. Like its predecessor, PowerPlex® 35GY System, the PowerPlex® 18E System includes two Quality Indicators (QIS and QIL) that aid in determining if poor quality profiles are due to degradation, inhibition, or absence of human DNA. The figure below demonstrates how the Quality Indicators provide helpful information about a sample run with PowerPlex® 35GY System. The QIs will work in a similar fashion in the PowerPlex® 18E System.
The Quality Indicators help take the conjecture out of determining whether or not the amplification was successful by confirming if there is DNA present. Additionally, they can indicate inhibition that was not observed during the quantification step. Lastly, knowing whether the sample was inhibited or degraded enables you to make an informed decision on whether or not to rework the samples. If inhibited, laboratories can choose to dilute samples for PCR or re-purify them to reduce inhibitor load. If the sample is degraded, a laboratory may choose to add more template DNA (if available) to push the high molecular weight markers above threshold.
Figure 3: Quality Indicators provide helpful information about a sample run with PowerPlex® 35GY System. The QIs will work in a similar fashion in the PowerPlex® 18E System. Panel A shows a successful, balanced STR profile with balanced QIS and QIL peaks, indicating successful amplification from high quality template DNA. Panel B shows no STR peaks with balanced QIS and QIL peaks, indicating that no template DNA was amplified in the sample. Panel C is an example of a sloping STR profile with balanced QIS and QIL peaks, indicating that the sample is degraded. Panel D is a sloping STR profile but with a low or missing QIL peak on the right. This suggests that the sample is inhibited. In cases where the electropherogram shows that neither QI peak is present, then amplification has failed.
Mini-STRs Offer Improved Success with Difficult Samples
Highly degraded samples are often seen in missing persons cases, forensic casework and mass disasters. Various environmental conditions can lead to severe degradation of human DNA samples, which often produce incomplete or no STR profiles due to larger loci that often “drop out”. With most of the loci in the PowerPlex® 18E System under 250bp, laboratories will see improved results when processing cold case samples or newer, more difficult samples. The figure below shows an electropherogram of degraded DNA from a femur where alleles were called in 17 out of 18 loci. Also note the high QIL peaks, indicating that the amplification was not inhibited.
Figure 4: Improved Results with More Mini-STRs in the PowerPlex® 18E System. Extracted DNA (1ng) from a femur was amplified using the PowerPlex® 18E System. Amplification products were separated on the Spectrum CE System and analyzed using GeneMarker® HID Software for Spectrum CE Systems.
In summary, the PowerPlex® 18E System is ideal for working with compromised samples—showing robust amplification in the presence of inhibitors and improved results when working with degraded samples due to the number of loci below 250bp. Download the poster or contact your local Promega representative to learn more about our latest 8-color PowerPlex® Systems.