Garvin A.M.,Confarma France SARL |
Fischer A.,Crime Laboratory |
Schnee-Griese J.,Crime Laboratory |
Jelinski A.,Crime Laboratory |
And 7 more authors.
Investigative Genetics | Year: 2012
Background: Profiling sperm DNA present on vaginal swabs taken from rape victims often contributes to identifying and incarcerating rapists. Large amounts of the victim's epithelial cells contaminate the sperm present on swabs, however, and complicate this process. The standard method for obtaining relatively pure sperm DNA from a vaginal swab is to digest the epithelial cells with Proteinase K in order to solubilize the victim's DNA, and to then physically separate the soluble DNA from the intact sperm by pelleting the sperm, removing the victim's fraction, and repeatedly washing the sperm pellet. An alternative approach that does not require washing steps is to digest with Proteinase K, pellet the sperm, remove the victim's fraction, and then digest the residual victim's DNA with a nuclease.Methods: The nuclease approach has been commercialized in a product, the Erase Sperm Isolation Kit (PTC Labs, Columbia, MO, USA), and five crime laboratories have tested it on semen-spiked female buccal swabs in a direct comparison with their standard methods. Comparisons have also been performed on timed post-coital vaginal swabs and evidence collected from sexual assault cases.Results: For the semen-spiked buccal swabs, Erase outperformed the standard methods in all five laboratories and in most cases was able to provide a clean male profile from buccal swabs spiked with only 1,500 sperm. The vaginal swabs taken after consensual sex and the evidence collected from rape victims showed a similar pattern of Erase providing superior profiles.Conclusions: In all samples tested, STR profiles of the male DNA fractions obtained with Erase were as good as or better than those obtained using the standard methods. © 2012 Garvin et al.; licensee BioMed Central Ltd.
Grubb J.C.,Forensic Biology |
Horsman-Hall K.M.,Forensic Biology |
Sykes K.L.V.,Forensic Biology |
Schlisserman R.A.,Forensic Biology |
And 5 more authors.
Journal of Forensic Sciences | Year: 2010
Automated platforms used for forensic casework sample DNA extraction need to be versatile to accommodate a wide variety of sample types, thus protocols frequently need modification. In this study, DNA IQ™ methods previously developed for the Biomek® 2000 Automation Workstation were adapted for the Teleshake Unit using normal volumes and all deepwell extraction, and a large volume DNA IQ™ method developed. DNA purification without detectable contamination of adjacent reagent blanks is reported in the extraction of tissue samples containing several micrograms of DNA. Sensitivity and contamination studies demonstrated similar performance with the manual organic extraction method for bloodstain dilution samples. Mock casework samples demonstrated the effectiveness of the Teleshake and Teleshake large volume methods. Because of the performance and increased versatility of the DNA IQ™ extraction with these modifications, the Teleshake Unit has been implemented in both normal and large volume automated DNA extractions at the Virginia Department of Forensic Science. © 2010 American Academy of Forensic Sciences.