R v Bropho: Careful interpretation of DNA evidence required for courtroom decision-making

R v. Bropho (2004) 36 SR (WA) 328: (2004) WADC 182, a judgement of the District Court of Western Australia, has highlighted again the need for the careful interpretation of the results of independence testing with regard to DNA interpretation. The ruling is unhelpful in this regard and if implemented will be seriously counter-productive. This article examines the correct approach to the interpretation of these results and attempts to clarify additional ambiguities thatmay otherwise impact on the appropriate asssessment of DNA evidenc ein Australian courts

Population data from sub-populations of the Northern Territory of Australia for 15 autosomal short tandem repeat (STR) loci.

It is a requirement that forensic DNA profiling evidence be accompanied by an estimation of its weight, in order that the court can assign an appropriate probative value to the evidence during legal proceedings. There are various models by which this estimation can be made, but each relies on approximations of the allele frequencies in the relevant population. It is also important to assess relevant population genetic features of the available data. This report provides allele frequencies and estimates of common population genetic parameters for the major sub-populations of the Northern Territory of Australia genotyped at 15 autosomal short tandem repeat (STR) loci

How reliable is the sub-population model in DNA testimony?

The performance of the sub-population model first proposed by Balding and Nichols [D.J. Balding, R.A. Nichols, DNA profile match probability calculation: how to allow for population stratification, relatedness, database selection and single bands. Forensic Sci. Int. 64 (1994) 125-140] is examined using a simulation approach. This work extends the investigations of Curran et al. [J.M. Curran, J.S. Buckleton, and C.M. Triggs, What is the magnitude of the sub-population effect? Forensic Sci. Int. 135 (2003) 1-8]. In particular the effect of underestimating the coancestry coefficient, θ, and the effect of departures from the modelling assumptions were investigated. The model tends to give strongly conservative estimates if the estimate for the coancestry coefficient is accurate. If this coefficient is underestimated then a larger fraction of cases give non-conservative estimates. Departures from the modelling assumption that the sub-population is in Hardy-Weinberg and linkage equilibria appear to have very little effect. © 2005 Elsevier Ireland Ltd. All rights reserved

A comprehensive analysis of microsatellite diversity in Aboriginal Australians.

Indigenous Australians have a unique evolutionary history that has resulted in a complex system of inter and intra-tribal relationships. While a number of studies have examined the population genetics of indigenous Australians, most have used a single sample to illuminate details of the global dispersal of modern humans and few studies have focussed on the population genetic features of the widely dispersed communities of the indigenous population. In this study we examine the largest Aboriginal Australian sample yet analysed (N = 8,868) at fifteen hypervariable autosomal microsatellite loci. A comprehensive analysis of differentiation indicates different levels of heterogeneity among indigenous peoples from traditional regions of Aboriginal Australia. The most genetically differentiated populations inhabit the North of the country, in particular the Tiwi of Melville and Bathurst islands, Arnhem Land (itself divided into West and East Arnhem), and Fitzmaurice regions. These tribal groups are most differentiated from other Aboriginal Australian tribes, especially those of the Central Desert regions, and also show marked heterogeneity from one another. These genetic findings are supportive of observations of body measurements, skin colour, and dermatoglyphic features which also vary substantially between tribes of the North (e.g. Arnhem Land) and Central Australian regions and, more specifically, between the Tiwi and West and East Arnhem tribes. This study provides the most comprehensive survey of the population genetics of Aboriginal Australia

Use of subpopulation data in Australian forensic DNA casework

DNA profiling evidence presented in court should be accompanied by a reliable estimate of its evidential weight. In calculating such statistics, allele frequencies from commonly employed autosomal microsatellite loci are required. These allele frequencies should be collected at a level that appropriately represents the genetic diversity that exists in the population. Typically this occurs at broadly defined bio-geographic categories, such as Caucasian or Asian. Datasets are commonly administered at the jurisdictional level. This paper focuses on Australian jurisdictions and assesses whether this current practice is appropriate for Aboriginal Australian and Caucasian populations alike. In keeping with other studies we observe negligible differences between Caucasian populations within Australia when segregated geographically. However segregation of Aboriginal Australian population data along contemporary State and Territory lines appears to mask the diversity that exists within this subpopulation. For this reason datasets collated along more traditional lines may be more appropriate, particularly to distinguish the most genetically differentiated populations residing in the north of the continent. © 2007 Elsevier Ireland Ltd. All rights reserved

Population data from the New South Wales Aboriginal Australian sub-population for the profiler plus autosomal short tandem repeat (STR) loci.

It is a requirement that forensic DNA profiling evidence be accompanied by an estimation of its weight, in order that the court can assign an appropriate probative value to it during legal proceedings. There are various models by which this estimation can be made, but each relies on approximations of the allele frequencies in the relevant population. This report provides the results of population genetic analyses at nine autosomal short tandem repeat (STR) loci for the Aboriginal Australian sub-population of New South Wales, Australia

Comparing the growth and effectiveness of forensic DNA databases

Forensic DNA databases have altered the landscape of the criminal justice system and re-shaped the field of forensic science. Whilst there has been widespread commentary regarding the legal and socio-political basis of DNA databases, there remains a lack of meaningful empirical assessment of database performance and effectiveness. In this research DNA database growth and effectiveness has been assessed statistically from data collated from major international databases. © 2008 Elsevier Ireland Ltd. All rights reserved

Evidence in support of self-declaration as a sampling method for the formation of sub-population DNA databases.

Well constructed sub-population databases are fundamental to the application of DNA-based forensic statistics. The size of such databases can affect the ability to examine adequately statistical or population genetic features, and the integrity of both the DNA profile and associated ethnicity information is also of importance. Use of short tandem repeat (STR) DNA profiling technology and the thoughtful construction of the governing legislation has seen large databases of DNA profiles collated for the four major sub-populations of New Zealand. Examination of the data illustrates the suitability of self-declaration as a means of categorizing samples on the basis of ethnicity