The Potential Advantages of Digital PCR When Performing Molecular Measurement
Posted 20th February 2017 by Jane Williams
Jim Huggett’s research focuses on molecular diagnostics, genomics and nucleic acids, including cancer and foetal genetic analysis and the diagnosis of infectious diseases. We interviewed him about the latest developments and the latest advances in qPCR research.
Digital PCR and its applications
Digital PCR is the first method to essentially allow us to count individual DNA molecules. This investigation is centred on measurement research of PCR and potential problems related to the quality of the sample. For instance, this may occur when a digital PCR measures certain results and then a different method, like fluorescence, reports diverse measurements. At this stage, it’s a matter of defining the source of error variance and bias that might be incorporated in such values.
We did some work across different laboratories looking at the variance that ensues in the KRAS gene that can be used to guide treatments of certain types of cancer. Our group in Paris speculated that quantification may be necessary and so the first half of my talk was comparing 21 laboratories quantifying the amounts of this KRAS gene or a different KRAS variant in both synthetic material and mixes of KRAS and water. Eighteen of these laboratories reported corrected results within the error range.
The future of the field: five years and beyond
Experts will continue to characterise and establish digital PCR and define how it can be used as a reference method. For example, current clinical virology by far is the most advanced application of molecular quantification in patient care. This can be achieved via qPCR and by calibrating this to international standards applying international units.
However, this calibration requires getting reference materials from the WHO to generate secondary reference materials. We’re very interested in seeing whether digital PCR can support that value assigned. Therefore, digital PCR is supporting current clinical use of qPCR because this method is widely used in clinic. If digital PCR can reduce the variation between laboratories, there might be further settings of application.
Applying Digital PCR in HIV
HIV diagnosis is a good example which is currently performed efficiently using digital PCR. In this process, there’s a need to lead testing while treating people accordingly and diagnosing guided treatments depending on which percentage of the virus is present. But certainly, at the moment there’s an explosion in terms of precision and personalised medicine, and KRAS is a good example where the tumour is treated with specific drugs that are working with the tumour. People have lots of hopes for tailoring personalised and precision medicine which might be causing serious adverse events in certain groups of people but can be very effective in other groups or populations.
The role of quantification in medicine can be interesting because as we advance these methods, people in the field want to acknowledge if quantification can give a better clinical definition. At the moment, our research checks the response of a particular method in a group of patients. Nevertheless, not enough studies are carried out in picking up a method and understanding its different nuances before applying it to the biology. This represents one of the gaps that research needs to find the answer to.
Dr Jim Huggett is a Principal Scientist at LGC and Senior Lecturer at the University of Surrey. His presentation at the 4th qPCR and Digital PCR Congress focused on the benefits of using digital PCR when performing molecular measurements.
Find out more about other qPCR and dPCR applications at the 3rd qPCR & Digital PCR Congress: USA.
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