title: A Y-short tandem repeat specific DNA enhancement strategy to aid the analysis of late reported (≥ 6 days) sexual assault cases.
abstract: The ability to obtain an autosomal short tandem repeat (STR) profile of the semen donor from the reproductive tract of a living victim rapidly diminishes as the post-coital interval increases. This is of concern where victims of sexual assault provide vaginal samples several days after the incident. In order to overcome the technological impediments inherent in autosomal DNA typing with extended interval samples, we previously employed the use of Y chromosome STR profiling which, by targeting only male DNA, can eliminate masking of the male profile (by the victim's alleles) or critical polymerase chain reaction reagent titration (due to excessive female DNA). Thus employing Y-STR profiling and additional enhancement strategies, we reported the ability to recover Y-STR profiles from samples collected 5 to 6 days after intercourse. However, the reproductive biology literature indicates that spermatozoa are found in the human cervix up to 7 to 10 days post coitus. Thus, even with improved extraction and profiling techniques, we failed to routinely recover profiles from samples collected ≥ 6 days after intercourse. The aim of the present work was to develop additional strategies to permit the recovery of male donor DNA profiles from ≥ 6 post-coital samples. Using nested polymerase chain reaction and DNA concentration procedures that together maximize the recovery and targeting of male DNA, we demonstrate the ability to obtain semen donor Y-STR profiles in extended interval post-coital samples collected 6 to 9 days after intercourse. This approaches the recognized time limits of sperm residence in the cervico-vaginal canal as described in the clinical literature.
authors: National Center for Forensic Science, USA.
authors: Ek
authors: E
authors: Hanson
authors: National Center for Forensic Science, USA Department of Chemistry, University of Central Florida, USA Jack.Ballantyne@ucf.edu.
authors: J
authors: J
authors: Ballantyne
mesh_terms: D041322:Chromosomes, Human, Y; D004247:DNA / Q000302:isolation & purification; D016172:DNA Fingerprinting / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D060885:Multiplex Polymerase Chain Reaction; D011902:Rape; D013094:Spermatozoa / Q000166:cytology; D013997:Time Factors
chemical_list: D004247:DNA
keywords: Y-short tandem repeat; extended interval post-coital cervico-vaginal samples; forensic science; nested polymerase chain reaction; selective DNA enhancement; sexual assault evidence