Life Technologies this week launched the next generation of its STR analysis kits for human identification and forensic applications, the GlobalFiler and GlobalFiler Express.
The new kits are the first to include all 24 STR loci commonly used in different combinations in the US, Europe, and other parts of the world for human identification.
As such, the kits are designed to extract more information from forensic samples, increase discrimination power, and eventually better enable international data sharing by including loci that overlap in different worldwide databases. The kits are also designed to increase testing throughput in order to reduce ballooning casework backlogs in forensic testing labs, Life Tech said.
John Gerace, head of applied sciences for Life Technologies, told PCR Insider this week that the new GlobalFiler kits are immediately available through Life Tech's global sales channels; however, they are not yet approved by the US Federal Bureau of Investigation for use in laboratories generating DNA profiles for inclusion in the National DNA Index System CODIS database.
The FBI is currently in the process of testing and validating the kits as part of an initiative to expand the number of core loci used in the US for forensic analysis, and the new Life Tech kits have been developed in accordance with those new guidelines, Gerace said.
"They haven't been approved, but that's going to happen," Gerace said. "They were developed according to these guidelines, but they have to be validated, and that takes some time, just for the US, to be CODIS compliant. But these kits are now globally available through all of our distribution channels. The name sort of implies that we're focusing … on global database compatibility."
In 1997 the FBI selected 13 core STR loci that are still being used for DNA data uploaded to NDIS. However, in May 2010 the agency organized a CODIS Core Loci Working Group to evaluate the need to expand the core loci to as many as 20 STRs.
The working group identified three factors in support of expanding the current CODIS core loci: "facilitating greater discrimination; assisting in missing person investigations; and encouraging international data sharing efforts by having more loci in common with other countries for comparison purposes," according to the FBI's timeline for the implementation of additional CODIS core loci.
According to a review authored by the National Institute of Standards and Technology and published in January in Forensic Science Review, currently only eight of the core set of 13 STR loci required for the US national database overlap with STR data gathered in the UK and most other European nations.
According to the review, a number of current commercial STR analysis kits enable simultaneous, multicolor fluorescence detection of 15 STRs and the sex-typing marker amelogenin in a single PCR reaction.
For example, both Life Tech's AmpFLSTR Identifiler and Promega's PowerPlex 16 kits enable typing of the US core 13 STRs plus two additional loci, according to the review. In addition, the authors wrote, "to meet the needs of the European community, new STR kits have been released since 2009" by various vendors. These kits include Promega's PowerPlex ESX and ESI 16 or 17; Life Tech's AmpFLSTR NGM and NGM Select; and Qiagen's ESSplex and ESSplex SE.
"These kits enable amplification of 15 or 16 STR loci with amelogenin using five-dye chemistry," the review states, adding that "while it would be nice to have future STR kits that include all 24 commonly used loci … there is limited electrophoretic space in creating STR kits with non-overlapping PCR products that are less than 500 [base pairs] in size using the five-dye channels available in current instrumentation. Perhaps with future kits and six-dye instrument capabilities, such as available with the [Life Tech] ABI 3500 and 3500xL Genetic Analyzers, all desired STR loci can be incorporated into a single kit."
Now, Life Tech has introduced such kits with GlobalFiler and GlobalFiler Express, which are optimized for use on those and other Life Tech capillary electrophoresis instruments, Gerace said.
GlobalFiler is designed for casework involving forensic samples taken from, for instance, a crime scene. These samples are often compromised, degraded, or scant, and require a different workflow than offered in the GlobalFiler Express, which is a "databasing product" that would be used, for instance, when taking a cheek swab from an individual, resulting in copious amounts of high-quality DNA.
Both kits include all 24 of the aforementioned STR loci, "delivering the ability to recover significantly more information from forensic samples and increasing discrimination power by up to nine orders of magnitude," resulting in faster and more powerful comparisons of forensic data, Life Tech said.
In addition, the kits feature a new, proprietary chemistry that enables 48 samples to be processed in less than two hours using Life Tech's forensic testing systems, which the company claims is five times faster than existing products — including its own AmpFLSTR kits.
"There are two aspects that represent a lot of innovation that has gone into these kits. One is that the … PCR amplification is dramatically faster" due to a "novel enzyme" that is employed in the kits, Gerace said.
"The other aspect is that … right now every product on the market has five fluorescent dyes … detected by the CE instrument. And this is the first commercially available kit that has six dyes," he added. "Basically this enables you to … label more amplicons per sample, per run, enabling you to get more information within a certain path length, if you will, per CE gel."
Lastly, the new Life Tech kits are designed to facilitate quicker and improved amplification of challenging samples, such as degraded human remains. This feature is a result of the PCR master mix used in the kits, "which enables you to get around PCR inhibitors that may be found in some challenging samples," Gerace said. "It has very good enzyme processivity; a very efficient enzyme system."
Life Tech believes that by employing its new kits, forensic testing laboratories can greatly reduce the growing backlog of casework. "To date, 44 countries have now implemented criminal offender DNA database programs with a combined offender sample pool of 40 million and growing," the company said in a statement.
Gerace added that "there is not a single other product on the market that we're aware of that can give you sample to result, with 48 samples, in less than two hours, and that's pretty dramatic."
Gerace noted that despite the introduction of the new GlobalFiler kits, Life Tech will still be selling and supporting its previous generation STR analysis kits.
"We have a life cycle management approach … because our products are being used in validated markets … and we can’t just remove products from the market because of how much effort and energy our customers have put in validating the workflow," he said.
"We do offer a professional service to go in and help customers revalidate onto new chemistries and platforms," he added. "We look at it from a total solution perspective, offering the full range of chemistries, instruments, as well as professional services to do the validation."