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Interpretation of DNA Mixtures—Australian and New Zealand consensus on principles
Forensic Science International: Genetics 3 (2009) 144–145
Contents lists available at ScienceDirect
Forensic Science International: Genetics journal homepage: www.elsevier.com/locate/fsig
Letter to the Editor Interpretation of DNA Mixtures—Australian and New Zealand consensus on principles
A R T I C L E I N F O
Keywords: Australian New Zealand Consensus DNA Mixture Interpretation
In 2006, the DNA Commission of the International Society of Forensic Genetics published their recommendations on the interpretation of DNA Mixtures [1]. The Technical UK working group on mixture interpretation [3] published their considerations of the former paper to place them in the context of those jurisdictions. These papers were followed by a further publication [4] which clarified some points in the original publication [1]. In addition, the German Stain Commission also published recommendations on the interpretation of mixed stains [2]. As a result of these papers, the Biology Specialist Advisory Group (BSAG) of the Australian and New Zealand forensic science community (laboratories included are detailed via the authors of this letter) met at a Critical Issues Workshop in March 2008, where, amongst other issues, DNA mixture interpretation was discussed. The recommendations in the original paper [1] served as a basis for discussion and the following consensus statement was agreed to by the laboratories represented: ‘‘The general principles described by the DNA Commission of the ISFG recommendations on mixture interpretation are accepted by the (Australian and New Zealand) Biology Specialist Advisory Group.’’ The BSAG had the following additional comment in relation to specific recommendations listed below that were originally detailed in [1]: Recommendation 1: The LR is the preferred approach to mixture interpretation. The RMNE approach is restricted to DNA profiles where the profiles are unambiguous. If the DNA crime stain profile is low level and some minor alleles are the same size as stutters of major alleles and/or if drop-out is possible, then the RMNE method may not be conservative. The likelihood ratio is a common approach to mixture interpretation in Australia and New Zealand. RMNE is considered an acceptable alternative approach to DNA interpretation. If the
crime stain DNA profile is low level and some minor alleles are the same size as stutters of major alleles, and/or if drop-out is possible, then extra consideration needs to be given to the method of statistical interpretation. Recommendation 2: Even if the legal system does not implicitly appear to support the use of the LR, it is recommended that the scientist is trained in the methodology and routinely uses it in case notes, advising the court in the preferred method before reporting the evidence in line with the court requirements. The scientific community has a responsibility to support the improvement of standards of scientific reasoning in the court-room. It is recommended that the scientist is trained in the primary methodology routinely used in their laboratory and has an understanding of other statistical approaches for DNA interpretations. The scientific community has a responsibility to support improvement of standards of scientific reasoning in the Justice system. Recommendation 3: The methods to calculate the LR of mixtures (not considering peak area) described by Evett et al. [5] and Weir et al. [6] are recommended. The methods to calculate likelihood ratios of mixtures (when not considering peak height or peak area) described by Curran et al. [7] is recommended. (Note that this paper follows the same general approach as [5] and [6], but incorporates the effect of population substructure.) No additional comment was made in relation to recommendations 4–9 of the original paper [1]. These recommendations can therefore be used as guidance on the interpretation of DNA profiling results.
References [1] P. Gill, C.H. Brenner, J.S. Buckleton, A. Carracedo, M. Krawczak, W.R. Mayr, N. Morling, M. Prinz, P.M. Schneider, B.S. Weir, DNA Commission of the International Society of Forensic Genetics: recommendations on the interpretation of mixtures, Forensic Sci. Int. 160 (2006) 90–101. [2] P. Gill, R.M. Brown, M. Fairley, M. Smyth, N. Simpson, B. Irwin, J. Dunlop, M. Greenhalgh, K. Way, S.J. Ferguson, T. Clayton, J. Guiness, National recommendations of the Technical UK DNA working group on mixtures interpretation for the NDNAD and for court going purposes, Forensic Sci. Int.: Genet. 2 (2008) 76–82. [3] N. Morling, I. Bastisch, P. Gill, P.M. Schneider, Interpretation of DNA mixtures—European consensus on principles, Forensic Sci. Int.: Genet. 1 (2007) 291–292. [4] P.M. Schneider, R. Fimmers, W. Keil, G. Molsberger, D. Patzelt, W. Pflug, T. Rothamel, K. Schmitter, H. Schneider, B. Brinkmann, Allgemeine Empfehlungen der Spurenkommission zur Bewertung von DNA-Mischspuren, Rechtsmedizin 16 (2006) 401–404. [5] I.W. Evett, C. Buffery, G. Willott, D. Stoney, A guide to interpreting single locus profiles of DNA mixtures in forensic cases, J. Forensic Sci. Soc. 31 (1991) 41–47. [6] B.S. Weir, C.M. Triggs, L. Starling, K.A.J. Stowell, J. Buckleton, Interpreting DNA mixtures, J. Forensic. Sci. 42 (1997) 213–222. [7] J.M. Curran, C.M. Triggs, J. Buckleton, B.S. Weir, Interpreting DNA Mixtures in Structured Populations, J. Forensic Sci. 44 (1999) 987–995.
1872-4973/$ – see front matter . Crown Copyright ß 2008 Published by Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.fsigen.2008.09.003
Letter to the Editor / Forensic Science International: Genetics 3 (2009) 144–145
Peta Stringer a,* John W. Scheffer a,b Pam Scott c,b Joannah Lee d,b Robert Goetz e,b Vanessa Ientile f,b Carmen Eckhoff g,b Gavin Turbett h,b Des Carroll i,b SallyAnn Harbison j,b a
Biology Division, Victoria Police Forensic Services Department, La Trobe R&D Park, 31 Forensic Drive, Macleod 3085, Victoria, Australia b Biology Specialist Advisory Group (BSAG) of the Senior Managers of Australian and New Zealand Forensic Science Laboratories (SMANZFL), Australia c Forensic Science Service Tasmania, 20 St. Johns Avenue, New Town, Tasmania 7008, Australia d Biological Criminalistics, Forensic and Data Centres, Australian Federal Police, GPO Box 401 Canberra 2601, Australian Capital Territory, Australia
145
e
Forensic Biology/DNA Laboratory, Division of Analytical Laboratories, Joseph St. Lidcombe 2141, New South Wales, Australia f DNA Analysis, Queensland Health Forensic and Scientific Services, 39 Kessels Road, Coopers Plains 4108, Queensland, Australia g Forensic Biology, Forensic Services Branch, Northern Territory Police Services, MacMillans Road, Berrimah 0828, Northern Territory, Australia h Forensic Biology, PathWest Laboratory Medicine Western Australia, Locked Bag 2009, Nedlands 6909, Western Australia, Australia i Forensic Science South Australia, 21 Divett Place, Adelaide 5000, South Australia, Australia j Institute of Environmental Science and Research Ltd., Mt Albert Science Centre, Private Bag 92021, Auckland, New Zealand *Corresponding author. Tel.: +61 3 94503602; fax: +61 3 94503601 E-mail address: [email protected] (P. Stringer) 9 September 2008
Contents lists available at ScienceDirect
Forensic Science International: Genetics journal homepage: www.elsevier.com/locate/fsig
Letter to the Editor Interpretation of DNA Mixtures—Australian and New Zealand consensus on principles
A R T I C L E I N F O
Keywords: Australian New Zealand Consensus DNA Mixture Interpretation
In 2006, the DNA Commission of the International Society of Forensic Genetics published their recommendations on the interpretation of DNA Mixtures [1]. The Technical UK working group on mixture interpretation [3] published their considerations of the former paper to place them in the context of those jurisdictions. These papers were followed by a further publication [4] which clarified some points in the original publication [1]. In addition, the German Stain Commission also published recommendations on the interpretation of mixed stains [2]. As a result of these papers, the Biology Specialist Advisory Group (BSAG) of the Australian and New Zealand forensic science community (laboratories included are detailed via the authors of this letter) met at a Critical Issues Workshop in March 2008, where, amongst other issues, DNA mixture interpretation was discussed. The recommendations in the original paper [1] served as a basis for discussion and the following consensus statement was agreed to by the laboratories represented: ‘‘The general principles described by the DNA Commission of the ISFG recommendations on mixture interpretation are accepted by the (Australian and New Zealand) Biology Specialist Advisory Group.’’ The BSAG had the following additional comment in relation to specific recommendations listed below that were originally detailed in [1]: Recommendation 1: The LR is the preferred approach to mixture interpretation. The RMNE approach is restricted to DNA profiles where the profiles are unambiguous. If the DNA crime stain profile is low level and some minor alleles are the same size as stutters of major alleles and/or if drop-out is possible, then the RMNE method may not be conservative. The likelihood ratio is a common approach to mixture interpretation in Australia and New Zealand. RMNE is considered an acceptable alternative approach to DNA interpretation. If the
crime stain DNA profile is low level and some minor alleles are the same size as stutters of major alleles, and/or if drop-out is possible, then extra consideration needs to be given to the method of statistical interpretation. Recommendation 2: Even if the legal system does not implicitly appear to support the use of the LR, it is recommended that the scientist is trained in the methodology and routinely uses it in case notes, advising the court in the preferred method before reporting the evidence in line with the court requirements. The scientific community has a responsibility to support the improvement of standards of scientific reasoning in the court-room. It is recommended that the scientist is trained in the primary methodology routinely used in their laboratory and has an understanding of other statistical approaches for DNA interpretations. The scientific community has a responsibility to support improvement of standards of scientific reasoning in the Justice system. Recommendation 3: The methods to calculate the LR of mixtures (not considering peak area) described by Evett et al. [5] and Weir et al. [6] are recommended. The methods to calculate likelihood ratios of mixtures (when not considering peak height or peak area) described by Curran et al. [7] is recommended. (Note that this paper follows the same general approach as [5] and [6], but incorporates the effect of population substructure.) No additional comment was made in relation to recommendations 4–9 of the original paper [1]. These recommendations can therefore be used as guidance on the interpretation of DNA profiling results.
References [1] P. Gill, C.H. Brenner, J.S. Buckleton, A. Carracedo, M. Krawczak, W.R. Mayr, N. Morling, M. Prinz, P.M. Schneider, B.S. Weir, DNA Commission of the International Society of Forensic Genetics: recommendations on the interpretation of mixtures, Forensic Sci. Int. 160 (2006) 90–101. [2] P. Gill, R.M. Brown, M. Fairley, M. Smyth, N. Simpson, B. Irwin, J. Dunlop, M. Greenhalgh, K. Way, S.J. Ferguson, T. Clayton, J. Guiness, National recommendations of the Technical UK DNA working group on mixtures interpretation for the NDNAD and for court going purposes, Forensic Sci. Int.: Genet. 2 (2008) 76–82. [3] N. Morling, I. Bastisch, P. Gill, P.M. Schneider, Interpretation of DNA mixtures—European consensus on principles, Forensic Sci. Int.: Genet. 1 (2007) 291–292. [4] P.M. Schneider, R. Fimmers, W. Keil, G. Molsberger, D. Patzelt, W. Pflug, T. Rothamel, K. Schmitter, H. Schneider, B. Brinkmann, Allgemeine Empfehlungen der Spurenkommission zur Bewertung von DNA-Mischspuren, Rechtsmedizin 16 (2006) 401–404. [5] I.W. Evett, C. Buffery, G. Willott, D. Stoney, A guide to interpreting single locus profiles of DNA mixtures in forensic cases, J. Forensic Sci. Soc. 31 (1991) 41–47. [6] B.S. Weir, C.M. Triggs, L. Starling, K.A.J. Stowell, J. Buckleton, Interpreting DNA mixtures, J. Forensic. Sci. 42 (1997) 213–222. [7] J.M. Curran, C.M. Triggs, J. Buckleton, B.S. Weir, Interpreting DNA Mixtures in Structured Populations, J. Forensic Sci. 44 (1999) 987–995.
1872-4973/$ – see front matter . Crown Copyright ß 2008 Published by Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.fsigen.2008.09.003
Letter to the Editor / Forensic Science International: Genetics 3 (2009) 144–145
Peta Stringer a,* John W. Scheffer a,b Pam Scott c,b Joannah Lee d,b Robert Goetz e,b Vanessa Ientile f,b Carmen Eckhoff g,b Gavin Turbett h,b Des Carroll i,b SallyAnn Harbison j,b a
Biology Division, Victoria Police Forensic Services Department, La Trobe R&D Park, 31 Forensic Drive, Macleod 3085, Victoria, Australia b Biology Specialist Advisory Group (BSAG) of the Senior Managers of Australian and New Zealand Forensic Science Laboratories (SMANZFL), Australia c Forensic Science Service Tasmania, 20 St. Johns Avenue, New Town, Tasmania 7008, Australia d Biological Criminalistics, Forensic and Data Centres, Australian Federal Police, GPO Box 401 Canberra 2601, Australian Capital Territory, Australia
145
e
Forensic Biology/DNA Laboratory, Division of Analytical Laboratories, Joseph St. Lidcombe 2141, New South Wales, Australia f DNA Analysis, Queensland Health Forensic and Scientific Services, 39 Kessels Road, Coopers Plains 4108, Queensland, Australia g Forensic Biology, Forensic Services Branch, Northern Territory Police Services, MacMillans Road, Berrimah 0828, Northern Territory, Australia h Forensic Biology, PathWest Laboratory Medicine Western Australia, Locked Bag 2009, Nedlands 6909, Western Australia, Australia i Forensic Science South Australia, 21 Divett Place, Adelaide 5000, South Australia, Australia j Institute of Environmental Science and Research Ltd., Mt Albert Science Centre, Private Bag 92021, Auckland, New Zealand *Corresponding author. Tel.: +61 3 94503602; fax: +61 3 94503601 E-mail address: [email protected] (P. Stringer) 9 September 2008