The effect of cleaning agents on the ability to obtain DNA profiles using the Identifiler™ and PowerPlex® Y multiplex kits.

A year after the introduction of Identifiler™ into the forensic DNA laboratories of the Institute of Environmental Science and Research Limited (ESR), increasing occurrences of dropout of the three loci, D7S820, D18S51, and FGA, were observed in samples where the DNA was not degraded and sufficient DNA was present that full DNA profiles were to be expected. The dropout was either partial or complete at these loci. Full profiles could sometimes be obtained by reamplification of samples using the same input amount of DNA. After a thorough investigation of the methods and procedures used in the laboratory, the cause of this inhibition was identified as the cleaning agent TriGene™ ADVANCE. This was determined after the deliberate addition of varying amounts of different cleaning reagents into the DNA amplification reactions. At concentrations of 0.004% TriGene™ ADVANCE caused inhibition resulting in tri-loci dropout. At concentrations of 0.04% and higher, complete inhibition was observed. An effect was also seen on the amplification of samples using the Y STR profiling system PowerPlex(®) Y. This work highlights the importance of checking all reagents and chemicals prior to use, even those with no apparent direct influence on the DNA profiling process.