Browsing by Subject "Probability"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Automatable Virtual Array Screening System for Rapid Analysis of Mitochondrial DNA Polymorphism(2002-05-01) Campbell, Rowan Stewart; Arthur J. Eisenberg; Bruce Budowle; John PlanzCampbell, Rowan Stewart, Automatable Virtual Array Screening System For Rapid Analysis of Mitochondrial DNA Polymorphism. Doctor of Philosophy (Biomedical Sciences), May, 2002, 156 pp., 11 tables, 48 illustrations, bibliography, 96 titles. The goal of this research project was to develop alternative methods to traditional forensic mtDNA sequence analysis. Conventional forensic mtDNA analysis requires the direct sequencing of Hypervariable Region I and Hypervariable Region II in both the forward and reverse directions. This method is time consuming, labor intensive and expensive. Two methods for determining mtDNA haplotypes through the direct interrogation of Single Nucleotide Polymorphisms with HVI and HVII have been developed. A Sequence Specific Oligonucleotide Hybridization assay was developed on the Luminex 100™ flow cytometer, as well as a Single Base Extension assay developed for the ABI Prism® 310 Genetic Analyzer. The SNP typing of mtDNA sequences can provide a significant benefit in many forensic and human identification cases. The reassociation of mass disaster remains, mass grave analysis, and the screening of large numbers of crime scene samples are examples of their potential application. Their inclusion as a standard screening tool would be high beneficial since more extensive DNA analysis would be reserved for those samples that possess the greatest evidentiary value. In a blind study of 50 samples, the Sequence Specific Oligonucleotide Hybridization assay incorrectly identified the mtDNA haplotypes in 7 samples, whereas the Single Base Extension assay correctly identified each of the SNP positions interrogated. The SNaPshot™ primer extension assay was approximately 20-25 times more sensitive than the standard sequencing approach. This would suggest that this system could be a viable alternative to sequence analysis when samples are limited, as well as being more robust in detection and typing of heteroplasmic sites. A statistical evaluation of the SNP panels revealed that the genetic diversity estimated for the 50 Southwestern Hispanic samples tested was 0.9624 for the primer extension array and 0.9559 for the hybridization-based array. The probability of two randomly selected individuals from a population group having the same mtDNA haplotype was 0.0568 for the Single Base Extension assay and 0.0632 for the Sequence Specific Oligonucleotide Hybridization assay. A forensic mtDNA SNP array consisting of the positions evaluated in this study could provide a reasonable alternative to the full sequencing of the HVI and HVII regions.Item Evaluation of forensic DNA mixture evidence: protocol for evaluation, interpretation, and statistical calculations using the combined probability of inclusion(BioMed Central Ltd., 2016-08-31) Bieber, Frederick R.; Buckleton, John S.; Budowle, Bruce; Butler, John M.; Coble, Michael D.BACKGROUND: The evaluation and interpretation of forensic DNA mixture evidence faces greater interpretational challenges due to increasingly complex mixture evidence. Such challenges include: casework involving low quantity or degraded evidence leading to allele and locus dropout; allele sharing of contributors leading to allele stacking; and differentiation of PCR stutter artifacts from true alleles. There is variation in statistical approaches used to evaluate the strength of the evidence when inclusion of a specific known individual(s) is determined, and the approaches used must be supportable. There are concerns that methods utilized for interpretation of complex forensic DNA mixtures may not be implemented properly in some casework. Similar questions are being raised in a number of U.S. jurisdictions, leading to some confusion about mixture interpretation for current and previous casework. RESULTS: Key elements necessary for the interpretation and statistical evaluation of forensic DNA mixtures are described. Given the most common method for statistical evaluation of DNA mixtures in many parts of the world, including the USA, is the Combined Probability of Inclusion/Exclusion (CPI/CPE). Exposition and elucidation of this method and a protocol for use is the focus of this article. Formulae and other supporting materials are provided. CONCLUSIONS: Guidance and details of a DNA mixture interpretation protocol is provided for application of the CPI/CPE method in the analysis of more complex forensic DNA mixtures. This description, in turn, should help reduce the variability of interpretation with application of this methodology and thereby improve the quality of DNA mixture interpretation throughout the forensic community.