DNA 17 – The New DNA Profiling Standard
Since July 2014, a new and updated method of DNA profiling was unveiled by the National DNA Database (NDNAD), which serves to revolutionise the way DNA samples are processed.
The development of DNA 17 was a result of the Treaty of Prüm, which involved the exchanging of information between jurisdictions throughout Europe. It was therefore necessary to standardise the information produced from the various DNA kits used throughout Europe so that information could be easily compared between countries.
The previously used SGM Plus® system was introduced in 1999 and examined 10 target areas of DNA plus a gender marker. DNA 17 incorporates these 10 as well as a further 6 target areas, plus the gender marker, thus greatly reducing the chance of two unrelated individuals samples matching. The probability of a chance match between individuals is given as one in a billion. As well as this, DNA 17 is also highly sensitive to smaller amounts of DNA (often referred to as low template DNA). Previously, samples less than 250pg were unable to be analysed due to the inability to sufficiently amplify to a high enough quality, whereas DNA 17 has been shown to produce a DNA profile from just a few cells when really pushed. A further advantage of this improved sensitivity is that DNA profiles can be retrieved from badly degraded or poor quality samples.
The increased sensitivity of DNA 17 does, however, have its drawbacks. As DNA is likely to be detected in many more cases, it is important to bear in mind that there is a greater risk of detecting contaminant DNA, such as that from a passerby or someone working at the crime scene. Care therefore needs to be taken in order to appropriately eliminate innocent individuals from police inquiries.
But before we get too excited and rejoice in this breakthrough technology, a recent £6 million investment by the government in Scotland has enabled the laboratories in the Scottish Crime Campus at Gartcosh, North Lanarkshire to begin using a technique known imaginatively as DNA 24. As you’ve probably guessed, this technique examines 24 target areas of DNA giving it even more discriminatory power than that offered by DNA 17. The benefits and limitations though remain much the same.
Both DNA 17 and DNA 24 will prove extremely valuable to previously unsolved cases, which may now be re-opened. Samples which were deemed inadequate for analysis many years ago can now be re-studied using these highly sensitive methods, bringing justice to victims and their families long after the crime was committed.