Inferring ancestral origin using a single multiplex assay of ancestry-informative marker SNPs

Tests that infer the ancestral origin of a DNA sample have considerable potential in the development of forensic tools that can help to guide crime investigation. We have developed a single-tube 34-plex SNP assay for the assignment of ancestral origin by choosing ancestry-informative markers (AIMs) exhibiting highly contrasting allele frequency distributions between the three major population-groups. To predict ancestral origin from the profiles obtained, a classification algorithm was developed based on maximum likelihood. Sampling of two populations each from African, European and East Asian groups provided training sets for the algorithm and this was tested using the CEPH Human Genome Diversity Panel. We detected negligible theoretical and practical error for assignments to one of the three groups analyzed with consistently high classification probabilities, even when using reduced subsets of SNPs. This study shows that by choosing SNPs exhibiting marked allele frequency differences between population-groups a practical forensic test for assigning the most likely ancestry can be achieved from a single multiplexed assay.     

Sensitive and specific quantification of human genomic deoxyribonucleic acid (DNA) in forensic science specimens: casework examples.

We describe the forensic science application of a method for quantification of human genomic deoxyribonucleic acid (DNA). The two cases cited in this report involve DNA samples extracted from skin tissue and bloodstained clothing recovered from different crime scenes. High-molecular-weight DNA was recovered from both specimens, and the concentrations of these DNAs were estimated to be approximately 0.5 microgram/microL by ethidium bromide/agarose gel electrophoresis. Using the human-specific DNA probe p17H8 (locus D17Z1) to quantify the amount of human genomic DNA in these samples, it is shown that less than 1% of the DNA isolated from the skin tissue is of human origin and that the DNA isolated from the bloodstained clothing is effectively devoid of human DNA sequences. These case examples illustrate the need to quantify not only the total amount of DNA recovered from forensic casework material, but also the proportion of the DNA that is of human origin.     

Looking Ahead: Addressing Ethical Challenges in Public Health Practice

Ethical challenges in public health can have a significant impact on the health of communities if they impede efficiencies and best practices. Competing needs for resources and a plurality of values can challenge public health policymakers and practitioners to make fair and effective decisions for their communities. In this paper, the authors offer an analytic framework designed to assist policymakers and practitioners in managing the ethical tensions they face in daily practice. Their framework is built upon the following set of six considerations: determining population-level utility of the proposed action; demonstrating evidence of need and effectiveness of actions; establishing fairness of goals and proposed implementation strategies; ensuring accountability; and, assessing expected efficiencies and costs associated with the proposed action. Together, these considerations create a structured guide to assist decision-makers in identifying potential ethical challenges and in assessing the moral considerations that underlie public health practice - and possibly even, if the conditions are met, reduce the creation of ethical tension. Although the authors'empirical experiences provide the basis for the framework advanced here, their approach remains to be tested and evaluated by public health practitioners.     

Sexual asphyxia in siblings

We present an accidental autoerotic asphyxiation of a 24-year-old man. Further investigation revealed that 18 years earlier, his brother, then 13, had been found dead, hanging in the family bathroom. Although that death had been ruled a suicide, reevaluation of the death scene indicates that this was also an autoerotic asphyxiation. This is the first reported case of sexual asphyxia involving siblings.     

Group-specific component: a review of the isoelectric focusing methods and auxiliary methods available for the separation of its phenotypes

This review compares the major isoelectric focusing methods that have been published for the separation of group-specific component (Gc) phenotypes since 1978. The various parameters of gel composition, size, electrical and running conditions and sample application points are listed. More current auxiliary methods are also listed. These relate to the extraction of Gc from bloodstains and its identification after isoelectric focusing. Protocols are then recommended for the forensic analysis of Gc phenotypes.