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Oral swab, as simple as that? A case report
Forensic Science International: Genetics Supplement Series 3 (2011) e111–e112
Contents lists available at ScienceDirect
Forensic Science International: Genetics Supplement Series journal homepage: www.elsevier.com/locate/FSIGSS
Oral swab, as simple as that? A case report A. Verzeletti *, N. Cerri, V. Cortellini, F. De Ferrari Department of Forensic Medicine, University of Brescia, Brescia, Italy
A R T I C L E I N F O
A B S T R A C T
Article history: Received 16 July 2011 Accepted 2 August 2011
Although performing oral swabs is a very simple, fast and cheap procedure, it should always be kept in mind the importance of this step in DNA typing. We report a case of voluntary contamination of oral swabs to alter a paternity testing. Therefore, carefully evaluate the oral cavity before collecting the swab, personally collect the sample, perform at least two oral swabs at two different sites of the oral cavity. ß 2011 Elsevier Ireland Ltd. All rights reserved.
Keywords: Oral swab Voluntary contamination DNA typing
1. Introduction Reference DNA samples are always needed to compare profiles obtained from evidence or to type subjects involved in paternity testing or in missing persons investigations. It is advantageous to obtain these reference DNA samples as rapidly and painlessly as possible. Blood is an excellent source, however it is costly and invasive, thus an alternative is needed. Oral swabs are very cheap, easy to perform, require no special training and provide an excellent source of DNA. Oral cavity cells collection involves wiping a cotton swab against the inside cheek of a subject’s mouth to collect some mucosal cells; the swab is then dried or can be pressed against a collection card to transfer mucosal cells for storage purposes [1]. However, it is important to keep in mind possible sources of contamination, fraudulent too. We report a case of voluntary contamination of oral swabs to alter a paternity testing. 2. Materials and methods An alleged father came to our attention for a paternity testing disposed by the court. Two oral swabs of two different brands were collected, at two different sites of the oral cavity. The oral cavity was grossly normal to a superficial inspection. For both the buccal swabs a 15 loci mixed profile regarding two individuals was obtained. Only the analysis of a small fragment of one of the two swabs allowed to highlight a single profile (Fig. 1),
* Corresponding author at: Piazzale Spedali Civili 1, 25123 Brescia, Italy. Tel.: +39 030 3995480; fax: +39 030 3995839. E-mail address: [email protected] (A. Verzeletti). 1875-1768/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.fsigss.2011.08.055
that was confirmed being the alleged father’s profile thanks to another buccal swab performed some time later. The evaluation of lab procedures allowed to exclude lab contamination (between samples during preparation, sporadic contamination of consumables, etc.) and also a primitive contamination of the two buccal swabs used (they were of two different brands). 3. Results and discussion The results, including indirect confirmations, were indicative of the fact that the alleged father tried to alter the oral cavity through scattering some biological material of another person. Even if the procedure of the oral swab is very simple, it should always be kept in mind that it can be easily altered. This is often not considered: sometimes the involved parties run the swab by themselves, even in an isolated place. UNI CEI EN ISO/IEC 17025 defines sampling as a ‘‘procedure whereby a part of a substance, material or product is taken to provide for testing or calibration of a representative sample of the whole’’, but ISO does not cover sampling in its widest sense in a forensic context and it does not refer directly to oral swab procedure. The ENFSI guidance does not take into deep consideration the problem, and FBI procedures (such as ‘‘FCO buccal collection kit instructions’’) do not expressly refer in preventing fraudulent contamination. This is more relevant considering DNA database, the increasing number of profiles and the need to be sure about the identity of persons involved, considering that electronic systems cannot care the problem [2,3]. Therefore it should always be kept in mind: carefully evaluate the oral cavity before collecting the swab, personally collect the sample, perform at least two oral swabs (better of different brands) at two different sites of the oral cavity.
e112
A. Verzeletti et al. / Forensic Science International: Genetics Supplement Series 3 (2011) e111–e112
Fig. 1. D21S11 locus: (A) fraudulent contamination (profile regarding two individuals) and (B) alleged father’s profile.
It should also be avoided the procedure by the subject him/ herself, the involved staff should be adequately trained and ad hoc procedures should be adopted. Conflict of interest None.
References [1] J.M. Butler, Forensic DNA Typing, 2nd ed., Elsevier Academic Press, 2005. [2] J. Hedman, L. Albinsson, C. Ansell, H. Tapper, O. Hansson, S. Holgersson, R. Ansell, A fast analysis system for forensic DNA reference samples, Forensic Sci. Int. Gen. 2 (2008) 184–189. [3] M. Steinlechner, W. Parson, Automation and high throughput for a DNA database laboratory: development of a laboratory information management system, Croat. Med. J. 43 (2001) 252–255.
Contents lists available at ScienceDirect
Forensic Science International: Genetics Supplement Series journal homepage: www.elsevier.com/locate/FSIGSS
Oral swab, as simple as that? A case report A. Verzeletti *, N. Cerri, V. Cortellini, F. De Ferrari Department of Forensic Medicine, University of Brescia, Brescia, Italy
A R T I C L E I N F O
A B S T R A C T
Article history: Received 16 July 2011 Accepted 2 August 2011
Although performing oral swabs is a very simple, fast and cheap procedure, it should always be kept in mind the importance of this step in DNA typing. We report a case of voluntary contamination of oral swabs to alter a paternity testing. Therefore, carefully evaluate the oral cavity before collecting the swab, personally collect the sample, perform at least two oral swabs at two different sites of the oral cavity. ß 2011 Elsevier Ireland Ltd. All rights reserved.
Keywords: Oral swab Voluntary contamination DNA typing
1. Introduction Reference DNA samples are always needed to compare profiles obtained from evidence or to type subjects involved in paternity testing or in missing persons investigations. It is advantageous to obtain these reference DNA samples as rapidly and painlessly as possible. Blood is an excellent source, however it is costly and invasive, thus an alternative is needed. Oral swabs are very cheap, easy to perform, require no special training and provide an excellent source of DNA. Oral cavity cells collection involves wiping a cotton swab against the inside cheek of a subject’s mouth to collect some mucosal cells; the swab is then dried or can be pressed against a collection card to transfer mucosal cells for storage purposes [1]. However, it is important to keep in mind possible sources of contamination, fraudulent too. We report a case of voluntary contamination of oral swabs to alter a paternity testing. 2. Materials and methods An alleged father came to our attention for a paternity testing disposed by the court. Two oral swabs of two different brands were collected, at two different sites of the oral cavity. The oral cavity was grossly normal to a superficial inspection. For both the buccal swabs a 15 loci mixed profile regarding two individuals was obtained. Only the analysis of a small fragment of one of the two swabs allowed to highlight a single profile (Fig. 1),
* Corresponding author at: Piazzale Spedali Civili 1, 25123 Brescia, Italy. Tel.: +39 030 3995480; fax: +39 030 3995839. E-mail address: [email protected] (A. Verzeletti). 1875-1768/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.fsigss.2011.08.055
that was confirmed being the alleged father’s profile thanks to another buccal swab performed some time later. The evaluation of lab procedures allowed to exclude lab contamination (between samples during preparation, sporadic contamination of consumables, etc.) and also a primitive contamination of the two buccal swabs used (they were of two different brands). 3. Results and discussion The results, including indirect confirmations, were indicative of the fact that the alleged father tried to alter the oral cavity through scattering some biological material of another person. Even if the procedure of the oral swab is very simple, it should always be kept in mind that it can be easily altered. This is often not considered: sometimes the involved parties run the swab by themselves, even in an isolated place. UNI CEI EN ISO/IEC 17025 defines sampling as a ‘‘procedure whereby a part of a substance, material or product is taken to provide for testing or calibration of a representative sample of the whole’’, but ISO does not cover sampling in its widest sense in a forensic context and it does not refer directly to oral swab procedure. The ENFSI guidance does not take into deep consideration the problem, and FBI procedures (such as ‘‘FCO buccal collection kit instructions’’) do not expressly refer in preventing fraudulent contamination. This is more relevant considering DNA database, the increasing number of profiles and the need to be sure about the identity of persons involved, considering that electronic systems cannot care the problem [2,3]. Therefore it should always be kept in mind: carefully evaluate the oral cavity before collecting the swab, personally collect the sample, perform at least two oral swabs (better of different brands) at two different sites of the oral cavity.
e112
A. Verzeletti et al. / Forensic Science International: Genetics Supplement Series 3 (2011) e111–e112
Fig. 1. D21S11 locus: (A) fraudulent contamination (profile regarding two individuals) and (B) alleged father’s profile.
It should also be avoided the procedure by the subject him/ herself, the involved staff should be adequately trained and ad hoc procedures should be adopted. Conflict of interest None.
References [1] J.M. Butler, Forensic DNA Typing, 2nd ed., Elsevier Academic Press, 2005. [2] J. Hedman, L. Albinsson, C. Ansell, H. Tapper, O. Hansson, S. Holgersson, R. Ansell, A fast analysis system for forensic DNA reference samples, Forensic Sci. Int. Gen. 2 (2008) 184–189. [3] M. Steinlechner, W. Parson, Automation and high throughput for a DNA database laboratory: development of a laboratory information management system, Croat. Med. J. 43 (2001) 252–255.