CONTAMINATED crime-scene DNA samples that would normally be written off as forensically useless can now be rescued, thanks to amplification enzymes that tolerate pollution.
Before a profile can be obtained from a DNA sample recovered from a crime scene, it must be amplified using enzymes called polymerases. Pollutants such as tobacco or aluminium from drink cans can stop the enzyme working, but now Johannes Hedman and colleagues at the have come up with some alternatives to the AmpliTaqGold enzyme, which is preferred by forensic labs.
The team amplified 32 polluted samples of saliva using three other polymerases regularly used to process non-forensic samples. Of these samples, 20 showed statistically significant improvements in the quality of the profile compared with using AmpliTaqGold (Biotechniques, vol 47, p 351).
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Hedman suggests that employing these enzymes could be useful for samples that till now would not yield a complete DNA profile.
