- OVERVIEWProviding an extensive range of services
- DNA-17The latest generation of forensic DNA profiling
- PACELaboratory robotics delivers a rapid and efficient service
- CRIME SCENE DNA SAMPLESFrom a range of sample types
- MAJOR CRIME DNADNA analysis is used in combination with a range of trace evidence techniques
- SPECIALIST DNA SERVICESInnovative services from Cellmark
DNA-17 is the latest generation DNA profiling system to be utilised by the National DNA Database® (NDNAD).
In 2014, the NDNAD led the biggest change to UK forensic DNA testing since 2000 by authorising the replacement of SGMplus™ (the STR multiplex used up to this point) with DNA-17 technologies. Three manufacturers, Life Technologies (Thermo Fisher Scientific), Promega Corporation and Qiagen supply DNA-17 multiplex kits and they all provide significant advantages over the previous SGMplus™ system.
After careful consideration, Cellmark chose to use the Life Technologies multiplex kits: NGM SElect™ (for crime scene DNA samples) and NGM SElectPlus™ (for PACE and reference samples) which were validated and accredited prior to their introduction at the end of July 2014.
Click the link to download our brochure for an overview of our DNA-17 service.
New improved chemistry
The DNA-17 STR multiplexes introduced in July 2014 have vastly improved reaction chemistry compared to the SGMplus kits, which were routinely used up to this point and which were designed in the mid-1990’s. The new chemistry delivers more robust PCR amplification, is less affected by any inhibitory chemicals (although rare due to improved DNA extraction procedures) and the increase in PCR cycle number provides stronger profiles and greater sensitivity.
The inclusion of a number of mini-STRs in DNA-17 multiplexes improves their ability to produce profile information from degraded samples. The primer sets of certain markers have been re-engineered to create mini-STRs which produce shorter (lower molecular weight) PCR products, therefore making them more likely to successfully amplify DNA that has been fragmented due to degradation.
Increased Sensitivity but More Mixtures
With the benefit of stronger profiles comes the complication of more DNA mixtures. The detection of lower levels of DNA increases the potential for detecting DNA from multiple contributors which means that DNA-17 profiles generally take longer to interpret and identify the individual contributors. Probabilistic profile interpretation software is therefore being increasingly used to assist with assessing mixed profiles and assigning statistical probabilities.
More than just the multiplex
Whilst the introduction of DNA-17 has been a significant step forward the STR multiplex is just one component in a multi-stage laboratory process that determines the successful outcome of a DNA profile. All the other components in the laboratory process, particularly DNA extraction strategy and profile interpretation, play key roles in determining the final result. Cellmark’s DNA scientists are renowned for their ability to produce results from the most challenging samples using a combination and variety of techniques and approaches.