The Paradyme™ 27GY STR System
A First Look Across the Spectrum CE Platform Family
Benjamin Krenke, Promega Corporation, Madison, WI, USA
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Forensic casework demands STR typing systems that perform reliably on challenging samples and deliver interpretable results in complex mixtures. The Paradyme™ 27GY STR System was developed to meet that demand by combining a compact 27-marker, 8-dye multiplex with a first-ever Reduced-Stutter Polymerase (RSP) technology. RSP produces clearer profiles that allow faster and more accurate mixture interpretation. The 8-dye design also allows for smaller amplicon sizes, improving performance with degraded forensic casework samples.
To support laboratories in running the Paradyme™ 27GY STR System, Promega offers three capillary electrophoresis platforms: the Spectrum CE System, 8-Capillary; the Spectrum CE System, 24-Capillary; and the Spectrum Compact CE System. This article demonstrates Paradyme™ 27GY STR System’s compatibility across three Spectrum CE Systems spanning a range of throughput capabilities, as well as two HID analysis software options.
The Paradyme™ 27GY STR System
The Paradyme™ 27GY STR System amplifies all 20 CODIS core loci along with Penta D, Penta E, and SE33 for enhanced discriminatory power and forensic database compatibility. Amelogenin and DYS391 are included to provide sex determination, while two rapidly mutating Y-STR markers (DYS570 and DYS576) are incorporated for enhanced male profile discrimination. The dual internal Quality Indicators (QIS and QIL) evaluate amplification efficiency and help identify sample inhibition or DNA degradation. With 23 markers under 350 base pairs, this 8-dye system is optimized for degraded and challenging samples that characterize real-world forensic casework.
Paradyme’s defining feature is RSP technology. Standard polymerase chemistry generates stutter artifacts. These are off-target peaks that appear at predictable positions relative to true alleles. Stutter complicates mixture interpretation, especially when a minor contributor’s alleles fall into a major contributor allele’s stutter position. RSP technology reduces these artifacts at the amplification stage (Figure 1). This makes mixture interpretation easier in several ways. Contributor number becomes easier to determine. Minor contributor alleles are more readily detected because they aren’t obscured by stutter peaks. Complex mixtures can be interpreted with greater confidence. Clearer profiles also enter probabilistic genotyping software with less artifact noise and produce statistics with higher certainty.
Figure 1: Comparison of a two-person mixture using a non-RSP (top) and Paradyme™ 27GY STR System (bottom) at a single STR locus, D13S317. Stutter peaks in the non-RSP example (top), which may be interpreted as additional minor contributor alleles and change the estimated number of contributors (NoC), are absent in the Paradyme™ 27GY STR System example (bottom).
Profiles Across the Spectrum CE Platform Family
Promega’s Spectrum CE portfolio spans three instrument configurations to fit different laboratory throughput needs and footprint constraints. The Spectrum CE System, 8-Capillary serves medium-throughput laboratories with a proven, reliable platform. The Spectrum CE System, 24-Capillary addresses the needs of high-volume laboratories. The Spectrum Compact CE System is a four-capillary instrument suited for lower-throughput environments or laboratories where bench space is limited. The Paradyme™ 27GY STR System was developed for use on all three Spectrum CE platforms.
Spectrum CE System, 8-Capillary
A 2800M positive control amplification and the Paradyme™ 27GY allelic ladder, both run on the Spectrum CE System, 8-Capillary, are shown in Figures 2A and 2B, respectively. The 2800M control profile demonstrates amplification of 27 markers in seven colors with an additional color for the Internal Lane Standard 500 (Figure 2A). The allelic ladder spans the full range of common alleles across all loci and serves as the sizing reference for profile analysis (Figure 2B).
Figure 2A: 2800M positive control profile generated with the Paradyme™ 27GY STR System on the Spectrum CE System, 8-Capillary. Data analyzed using GeneMarker®HID Software for Spectrum CE Systems.
Figure 2B: Allelic ladder for the Paradyme™ 27GY STR System, run on the Spectrum CE System, 8-Capillary. Data analyzed using GeneMarker®HID Software for Spectrum CE Systems.
Spectrum CE System, 24-Capillary
A representative 2800M positive control profile generated on the Spectrum CE System, 24-Capillary is shown in Figure 3. The 24-Capillary system extends throughput for high-volume laboratories while maintaining the same chemistry and analysis workflow as the rest of the Spectrum family.
Figure 3: 2800M positive control profile generated with the Paradyme™ 27GY STR System on the Spectrum CE System, 24-Capillary. Data analyzed using GeneMarker®HID Software for Spectrum CE Systems.
Spectrum Compact CE System
A representative 2800M positive control profile generated on the Spectrum Compact CE System is shown in Figure 4. Profile quality is consistent with the other Spectrum CE Systems, reflecting compatibility of the Paradyme™ 27GY STR System with different instrument configurations.
Figure 4: 2800M positive control profile generated with the Paradyme™ 27GY STR System on the Spectrum Compact CE System. Data analyzed using GeneMarker®HID Software for Spectrum CE Systems.
Software Flexibility
Paradyme™ 27GY STR System users are not limited to a single analysis pathway. The 2800M profile generated on the Spectrum CE System, 8-Capillary (Figure 2A) was reanalyzed using FaSTR™ DNA Software from Public Health and Forensic Science (PHF Science), fragment analysis software optimized for downstream use with STRmix™ probabilistic genotyping software (Figure 5). The ability to analyze data across multiple software platforms reflects Promega’s commitment to supporting laboratory flexibility in forensic casework analysis workflows.
Figure 5: 2800M positive control profile from the Spectrum CE System, 8-Capillary analyzed using FaSTR™ DNA software (PHF Science).
Conclusion
The Paradyme™ 27GY STR System represents a leap in the ability to interpret complex forensic mixtures, addressing stutter at the source rather than managing it downstream. Clearer profiles lead to easier and more accurate determination of the number of contributors, higher confidence in the detection of minor contributor alleles, and the potential to interpret mixtures that would previously have been inconclusive. The data presented here demonstrate that this capability is accessible across the full Spectrum CE platform family and compatible with multiple analysis software pathways. Whether a laboratory is processing a handful of samples per week or thousands, the Paradyme™ 27GY STR System consistently delivers the same data quality and analytical confidence.