Title

Y-Str Profiling In Extended Interval (≥3 Days) Postcoital Cervicovaginal Samples

Keywords

AmpFℓSTR® Yfiler™; Extended interval postcoital cervicovaginal samples; Forensic science; MinElute™; MPB; MPI; Multiplex DNA typing systems; Post-PCR purification; PowerPlex® Y; Y-PLEX™ 12; Y-STRs

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® Yfiler™ (Applied Biosystems), PowerPlex® Y (Promega) and Y-PLEX™ 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. © 2008 American Academy of Forensic Sciences.

Publication Date

1-1-2008

Publication Title

Journal of Forensic Sciences

Volume

53

Issue

2

Number of Pages

342-348

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1111/j.1556-4029.2008.00672.x

Socpus ID

41149162257 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/41149162257

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