Title

Y-STR profiling in extended interval (>= 3 days) postcoital cervicovaginal samples

Authors

Authors

K. A. Mayntz-Press; L. M. Sims; A. Hall;J. Ballantyne

Comments

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Abbreviated Journal Title

J. Forensic Sci.

Keywords

forensic science; Y-STRs; multiplex DNA typing systems; AmpFlSTR (R); Yfiler (R); PowerPlex (R) Y; Y-PLEX (TM) 12; MPI; MPB; extended interval; postcoital cervicovaginal samples; post-PCR purification; MinElute (TM); PCR AMPLIFICATION KIT; FORENSIC CASEWORK; DEVELOPMENTAL VALIDATION; MULTIPLEX SYSTEMS; TWGDAM VALIDATION; DNA ANALYSIS; SPERMATOZOA; PERSISTENCE; VAGINA; STRATEGIES; Medicine, Legal

Abstract

Depending upon specific situations, some victims of sexual assault provide vaginal samples more than 36-48 h after the incident. We have tested the ability of commercial and in-house Y-STR systems to provide DNA profiles from extended interval (>= 3 days) postcoital samples. The commercial Y-STR systems tested included the AmpFlSTR (R) Yfiler (TM) (Applied Biosystems), PowerPlex (R) Y (Promega) and Y-PLEX (TM) 12 (Reliagene) products whereas the in-house systems comprised Multiplex I (MPI) and Multiplex B (MPB). Three donor couples were recruited for the study. Postcoital cervicovaginal swabs (x2) were recovered by each of the three females at specified intervals after sexual intercourse (3-7 days). Each time point sample was collected after a separate act of sexual intercourse and was preceded by a 7-day abstention period. As a negative control, a precoital swab was also recovered prior to coitus for each sampling and only data from postcoital samples that demonstrated a lack of male DNA in the associated precoital sample was used. A number of DNA profile enhancement strategies were employed including sampling by cervical brushing, nondifferential DNA extraction methodology, and post-PCR purification. Full Y-STR profiles from cervicovaginal samples recovered 3-4 days after intercourse were routinely obtained. Profiles were also obtainable 5-6 days postcoitus although by this stage partial profiles rather than full profiles were a more likely outcome. The DNA profiles from the sperm fraction of a differential lysis were superior to that obtained when a nondifferential method was employed in that the allelic signal intensities were generally higher and more balanced and exhibited less baseline noise. The incorporation of a simple post-PCR purification process significantly increased the ability to obtain Y-STR profiles, particularly from 5- to 6-day postcoital samples. Remarkably an 8 locus Y-STR profile was obtained from a 7-day postcoital sample, which is approaching the reported time limit for sperm detection in the cervix.

Journal Title

Journal of Forensic Sciences

Volume

53

Issue/Number

2

Publication Date

1-1-2008

Document Type

Article

Language

English

First Page

342

Last Page

348

WOS Identifier

WOS:000254305900012

ISSN

0022-1198

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