Introduction of the DNase in forensic analysis

Abstract Laboratory DNA contamination is a frequent problem in forensic genetics, especially when extra PCR cycles are used to obtain acceptable amplified products from low copy number DNA samples. We have evaluated the use of the DNase I for forensic genetics studies. Initially we introduced known genomic DNA in the PCR reaction mix in order to simulate DNA contamination. Different conditions of action an inactivation of the DNase I were tested. Finally, we performed amplifications of low copy number samples employing homemade and commercially available STR amplification systems; in both cases decontamination was successful. We demonstrate that DNase I may be useful to reduce laboratory contamination in forensic genetics labs. Our protocol may be easily introduced in standard PCR protocols of commercial kits in order to be used routinely in low copy number DNA amplification.