A validation study of the Nucleix DSI-Semen kit--a methylation-based assay for semen identification.
The detection of semen can assist in reconstructing the events of a sexual assault and impact the outcome of legal dispositions. Many methods currently are used for detecting the presence of semen, but they all have limitations with regards to specificity, sample degradation/consumption, stability of biomolecule assayed, and/or incompatibility with downstream individual identification assays. DNA is routinely collected at sexual assault crime scenes and is widely used for individual identification. The DNA also carries methylation patterns that are tissue specific. To date, however, assays designed to exploit methylation patterns suffer from complex chemistries and unwieldy analyses. DSI-Semen™ kit uses a novel approach involving CpG methylation-sensitive restriction endonuclease digestion coupled to a multiplexed polymerase chain reaction (PCR) to generate an amplicon profile that makes it possible to determine whether the tissue source of a DNA sample was semen or non-semen. The assay returned an appropriate positive result for semen with neat semen, semen stains, and semen/non-semen tissue mixtures. The assay is robust and reliable, with a positive result for semen given as little as 31 pg of template DNA input. Low levels of semen were detected in mixtures of semen and other body fluids. UV-exposed samples and those in the presence of limited concentrations of known PCR inhibitors were typeable. The DSI-Semen™ kit provides a reliable tool for the determination of DNA being derived from semen.
Institute of Applied Genetics, Department of Forensic and Investigative Genetics, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA. bobby.larue@unthsc.edu
Bobby L
BL
LaRue
Jonathan L
JL
King
Bruce
B
Budowle
D000818:Animals; D001774:Blood Chemical Analysis; D004247:DNA / Q000187:drug effects; D053836:DNA Degradation, Necrotic; D016172:DNA Fingerprinting; D053938:DNA Fragmentation; D019175:DNA Methylation; D017931:DNA Primers; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D004586:Electrophoresis; D053803:Forensic Genetics / Q000295:instrumentation*; D006801:Humans; D016013:Likelihood Functions; D057230:Limit of Detection; D008297:Male; D018895:Microsatellite Repeats; D009061:Mouth Mucosa / Q000378:metabolism; D060885:Multiplex Polymerase Chain Reaction; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D012463:Saliva / Q000378:metabolism; D012661:Semen / Q000378:metabolism*; D012984:Software; D014466:Ultraviolet Rays
D017931:DNA Primers; D004247:DNA; D004262:DNA Restriction Enzymes