Need reliable DNA?

DNA collection has been embraced by a wide range of industries across the world. Pharmaceutical companies collect and archive human DNA samples for clinical drug trials. Law enforcement agencies collect DNA samples from convicted felons for inclusion in national DNA databases, a valuable tool in the fight against crime. Nature conservationists collect bird DNA from jet engines to determine the flight patterns of specific species. While the range of applications is large, they all share three common elements — collection, extraction yield and storage.

DNA is one of the essential elements for scientific research. It’s crucial that DNA is collected and stored to provide accuracy and consistency so that scientists can generate robust data. While most consider collection and storage the easiest part of the process, it can have great effects on quality and yield.

In a study conducted by GE Healthcare, we examined the yield and quality of DNA from blood samples applied to Whatman^TM FTA cards, using five common methods of DNA extraction. The data demonstrate that all five methods yield purified DNA of sufficient quantity and quality for both quantitative PCR and short tandem repeat analyses. For each of the five extraction methods, a minimum of 10 ng of genomic DNA was recovered from blood samples on FTA cards (see figure below). The amount of DNA extracted using each method increased as the disc size increased.

DNA extracted from FTA cards was measured using quantitative PCR (qPCR). DNA was subjected to short tandem repeat (STR) analysis to assess its quality.

Extracted DNA was measured using quantitative PCR (qPCR) and an ABI 7900HT Fast Real-Time PCR System (Applied Biosystems, Foster City, CA, USA). Reactions were prepared using the Quantifiler Human DNA Quantification Kit (4343895, Applied Biosystems). The DNA quantitation assay combines two 5′ nuclease assays. The first is a target-specific human DNA assay consisting of two primers for amplifying human DNA and one TaqMan MGB probe labelled with FAM dye for detecting the amplified sequence. The second assay is an internal PCR control (IPC) assay consisting of two primers for amplifying the IPC template DNA and one TaqMan MGB probe labelled with VIC dye for detecting the amplified IPC DNA. Standard curves for DNA quantitation were prepared using control DNA supplied with the kit.

STR analysis of extracted DNA was conducted using the Powerplex 16 System (Promega) according to the manufacturer’s instructions. Amplification was performed in a 9700-thermal cycler (Applied Biosystems), and amplification products were analysed on an ABI PRISM 3130XL Genetic Analyzer (Applied Biosystems) according to the manufacturer’s instructions.

All of the DNA extraction methods tested yielded sufficient DNA for effective amplification and STR analysis. STR data were generated to determine the accuracy of allele calls for DNA extracted from FTA cards. For each DNA extraction method, duplicates of DNA from FTA cards were run for three blood samples, three buccal samples collected using EasiCollect+ devices, and three buccal sample collected using separate foam swabs, resulting in a total of 18 samples per DNA extraction method. Note that the three samples were from three test subjects. Of the 90 STR profile collected, 87 samples provided quality data with accurate allele calls on the first attempt; three samples required a reinjection for 100% accurate allele calls. These data illustrate that commonly used DNA extraction methods and kits provide DNA of sufficient quantity and quality to support allele call accuracy as high as 100% in STR analysis.

Whilst blood may seem like an easy example to extract DNA from, we at GE Healthcare have continued to develop our FTA cards to ensure they can be used to collect a wide range of sample types: blood, plant cells, plasmids, cultured cells, solid tissue and buccal cells.

As our FTA card is a trusted product that has been used for many years, we have been able to store human DNA in blood samples on FTA for 22 years at ambient temperatures and demonstrate successful amplification by PCR. No other product can make that claim. FTA cards offer a compact room temperature storage system that reduces the need for precious freezer space and storage costs, improves sample accessibility and removes the cost associated with cold chain shipping.

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