Research paper| Volume 33, P110-116, March 2018

Download started.


Background levels of male DNA in the vaginal cavity

Published:December 05, 2017DOI:


      • 300 vaginal swabs from eight women were screened for the presence of male DNA following everyday activities.
      • 85.8% concordance was obtained between Quantifiler® Trio and Yfiler® Plus for the detection of male-specific DNA.
      • Full Y-STR profiles were detected for up to six days post intercourse.
      • The recovery of a Y-STR profile (≥three alleles) due to adventitious transfer of DNA from a male individual is not supported.
      • Approximately one in seven samples may display 1–2 unexpected Y-STR alleles (<400 RFU).


      In alleged sexual assault investigations, the detection of male DNA on female intimate swabs can be established through Y-STR profiling. However, in cases where the defendant lives in the same dwelling as the complainant, the defendant may argue that his DNA was transferred through normal social contact, and dispute that intimate contact occurred. This study aimed to determine whether or not male DNA could be detected in samples collected from the vaginal cavity after everyday activities. A total of 300 samples from eight individuals were subjected to DNA quantification and Y-STR amplification. Three donors reported sexual contact during the time of sampling, hence the detection of male-specific DNA in post-coital samples was concomitantly evaluated. The majority of samples (n = 237, 79%) were undetermined for male DNA by real-time PCR quantification. No Y-STR profiles having three or more alleles were obtained in these samples, with the exception of three samples which displayed three alleles each. One sample was collected six days post-coital, one sample likely presented artefacts, and one exhibited two alleles at the same locus. Male-specific quantification values were obtained for the remaining 63 samples (21%), however only 31 samples displayed alleles at three or more loci. Twenty-three of the 63 samples showed inhibition during real-time PCR quantification, and the majority of these exhibited no Y-STRs. A further three samples were excluded from the dataset due to possible contamination. The maximum confirmed time frame for obtaining a full Y-STR profile was six days post-coital, but may be longer in some donors. Overall concordance between DNA quantification and Y-STR amplification was 85.8%. This study demonstrates that obtaining a Y-STR profile comprising three or more alleles from a vaginal swab collected from a woman who has not participated in recent intimate sexual activities is not indicated. This suggests that there is unlikely to be detectable adventitious transfer of DNA from male individuals living in the same household as a female donor. However, approximately one in seven samples may display 1–2 unexpected allelic peaks (<400 RFU). These are unlikely to originate from the male partner or cohabitant of the donor and should be interpreted with extreme caution, and with every effort attempted to replicate results before a conclusion is derived about their relevance. These findings support the significance of male DNA profiles consisting of more than three alleles obtained from female intimate samples during investigations of alleged sexual assault.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Forensic Science International: Genetics
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Dartnall E.
        • Jewkes R.
        Sexual violence against women: the scope of the problem.
        Best Pract. Res. Clin. Obstet. Gynaecol. 2013; 27: 3-13
      1. New Zealand Ministry of Justice 2014 New Zealand Crime and Safety Survey.
        2015 (Retrieved July 2016. Main findings. Online ISBN 978–0-478–32451-8)
        • Triggs S.
        • Mossman E.
        • Jordan J.
        • Kingi V.
        Responding to Sexual Violence: Attrition in the New Zealand Criminal Justice System. Ministry of Women’s Affairs.
        2009 (Retrieved October 2016 ISBN 978–0-478252–48-4)
        • Newton M.
        The forensic aspects of sexual violence.
        Best Pract. Res. Clin. Obstet. Gynaecol. 2013; 27: 77-90
        • Meakin G.
        • Jamieson A.
        DNA transfer: review and implications for casework.
        Forensic Sci. Int-Gen. 2013; 7: 434-443
        • Speck P.
        • Ballantyne J.
        Post-coital DNA Recovery Study.
        2015 (Retrieved September 2016 Document No. 248682, NIJ Grant No. 2009-DN-BX-0023)
        • Sibille I.
        • Duverneuil C.
        • Lorin de la Grandmaison G.
        • Guerrouache K.
        • Teissière F.
        • Durigon M.
        • de Mazancourt P.
        Y-STR DNA amplification as biological evidence in sexually assaulted female victims with no cytological detection of spermatozoa.
        Forensic Sci. Int. 2002; 125: 212-216
        • Jones S.
        • Scott K.
        • Lewis J.
        • Davidson G.
        • Allard J.E.
        • Lowrie C.
        • McBride B.M.
        • McKenna L.
        • Teppett G.
        • Rogers C.
        • Clayson N.
        • Baird A.
        DNA transfer through nonintimate social contact.
        Sci. Justice. 2016; 56: 90-95
        • Graham E.A.M.
        • Rutty G.N.
        Investigation into “normal” background DNA on adult necks: implications for DNA profiling of manual strangulation victims.
        J. Forensic Sci. 2008; 53: 1074-1082
      2. Applied Biosystems by Life Technologies Yfiler® Plus PCR Amplification Kit User Guide.
        Thermo Fisher Scientific, Inc., 2017 (Publication no. 4485610, revision B. 2014.)
        • McDonald A.
        • Jones E.
        • Lewis J.
        • O’Rourke P.
        Y-STR analysis of digital and/or penile penetration cases with no detected spermatozoa.
        Forensic Sci. Int-Gen. 2015; 15: 84-89
        • Boiso L.
        • Sanga M.
        • Hedman J.
        DTT quenches the passive reference signal in real-time PCR.
        Forensic Sci. Int.-Gen. Suppl. Ser. 2015; 5: e5-e6