Results of the 2003-2004 GEP-ISFG collaborative study on mitochondrial DNA: focus on the mtDNA profile of a mixed semen-saliva stain.

We report here a review of the seventh mitochondrial DNA (mtDNA) exercise undertaken by the Spanish and Portuguese working group (GEP) of the International Society for Forensic Genetics (ISFG) corresponding to the period 2003-2004. Five reference bloodstains from five donors (M1-M5), a mixed stain of saliva and semen (M6), and a hair sample (M7) were submitted to each participating laboratory for nuclear DNA (nDNA; autosomal STR and Y-STR) and mtDNA analysis. Laboratories were asked to investigate the contributors of samples M6 and M7 among the reference donors (M1-M5). A total of 34 laboratories reported total or partial mtDNA sequence data from both, the reference bloodstains (M1-M5) and the hair sample (M7) concluding a match between mtDNA profiles of M5 and M7. Autosomal STR and Y-STR profiling was the preferred strategy to investigate the contributors of the semen/saliva mixture (M6). Nuclear DNA profiles were consistent with a mixture of saliva from the donor (female) of M4 and semen from donor M5, being the semen (XY) profile the dominant component of the mixture. Strikingly, and in contradiction to the nuclear DNA analysis, mtDNA sequencing results yield a more simple result: only the saliva contribution (M4) was detected, either after preferential lysis or after complete DNA digestion. Some labs provided with several explanations for this finding and carried out additional experiments to explain this apparent contradictory result. The results pointed to the existence of different relative amounts of nuclear and mtDNAs in saliva and semen. We conclude that this circumstance could strongly influence the interpretation of the mtDNA evidence in unbalanced mixtures and in consequence lead to false exclusions. During the GEP-ISFG annual conference a validation study was planned to progress in the interpretation of mtDNA from different mixtures.

Formulation and communication of evaluative forensic science expert opinion-A GHEP-ISFG contribution to the establishment of standards.

Communicating and interpreting genetic evidence in the administration of justice is currently a matter of great concern, due to the theoretical and technical complexity of the evaluative reporting and large difference in expertise between forensic experts and law professionals. A large number of initiatives have been taken trying to bridge this gap, contributing to the education of both parties. Results however have not been very encouraging, as most of these initiatives try to cope globally with the problem, addressing simultaneously theoretical and technical approaches which are in a quite heterogeneous state of development and validation. In consequence, the extension and complexity of the resulting documents disheartens their study by professionals (both jurists and geneticists) and makes a consensus very hard to reach even among the genetic experts' community. Here we propose a 'back-to-basics', example-driven approach, in which a model report for the two most common situations faced by forensic laboratories is presented. We do hope that this strategy will provide a solid basis for a stepwise generalisation.

STR frequencies for the PowerPlex 16 System Kit in a population from Northeast Spain.

The aim of this paper, was to obtain the frequencies for the 15 STR loci included in the PowerPlex 16 System Kit on a population of 204 unrelated Caucasian individuals living in Northeast of Spain in order to use for forensic purposes. Statistical analyses were performed using the programs GENEPOP version 3.3 and Powerstats version 1.2. The results showed that all the loci met Hardy-Weinberg expectations.

Results of the 1999-2000 collaborative exercise and proficiency testing program on mitochondrial DNA of the GEP-ISFG: an inter-laboratory study of the observed variability in the heteroplasmy level of hair from the same donor.

The Spanish and Portuguese working group (GEP) of international society for forensic genetics (ISFG) 1999-2000 collaborative exercise on mitochondrial DNA (mtDNA) included the analysis of four bloodstain samples and one hair shaft sample by 19 participating laboratories from Spain, Portugal and several Latin-American countries. A wide range of sequence results at position 16,093 of the HV1 (from T or C homoplasmy to different levels of heteroplasmy) were submitted by the different participating laboratories from the hair shaft sample during the first phase of this exercise. During the discussion of these results in the Annual GEP-ISFG 2000 Conference a second phase of this exercise was established with two main objectives: (i) to evaluate the incidence of the HV1 sequence heteroplasmy detected in Phase I across different sample types from the same donor including blood, saliva, and hair shafts, (ii) to perform a technical review of the electropherograms to evaluate the relative levels of heteroplasmies obtained by the different laboratories and also to examine the source of possible errors detected in Phase I. Anonymous review of the raw sequence data permitted the detection of three transcription errors and three errors due to methodological problems. Highly variable levels of heteroplasmy were found in the hair shaft and more stability in blood and saliva. Three laboratories found variable levels of heteroplasmy at position 16,093 across adjacent fragments from the same hair shaft. Two laboratories also described more than one heteroplasmic position from a single hair. The relevance of these findings for the interpretation of mtDNA data in the forensic context is also discussed.

The 2000-2001 GEP-ISFG Collaborative Exercise on mtDNA: assessing the cause of unsuccessful mtDNA PCR amplification of hair shaft samples.

We report the results of Spanish and Portuguese working group (GEP) of International Society of Forensic Genetics (ISFG) Collaborative Exercise 2001-2002 on mitochondrial DNA (mtDNA) analysis. 64 laboratories from Spain, Portugal and several Latin-American countries participated in this quality control exercise. Five samples were sent to the participating laboratories, four blood stains (M1-M4) and a sample (M5) consisting of two hair shaft fragments. M4 was non-human (Felis catus) in origin; therefore, the capacity of the labs to identify the biological source of this sample was an integral part of the exercise. Some labs detected the non-human origin of M4 by carrying out immuno-diffussion techniques using antihuman serum, whereas others identified the specific animal origin by testing the sample against a set of animal antibodies or by means of the analysis of mtDNA regions (Cyt-b, 12S, and 16S genes). The results of the other three human blood stains (M1-M3) improved in relation to the last Collaborative Exercises but those related to hairs yielded a low rate of success which clearly contrasts with previous results. As a consequence of this, some labs performed additional analysis showing that the origin of this low efficiency was not the presence of inhibitors, but the low quantity of DNA present in these specific hair samples and the degradation. As a general conclusion the results emphasize the need of external proficiency testing as part of the accreditation procedure for the labs performing mtDNA analysis in forensic casework.

Forensic analysis of dog (Canis lupus familiaris) mitochondrial DNA sequences: an inter-laboratory study of the GEP-ISFG working group.

A voluntary collaborative exercise aiming at the mitochondrial analysis of canine biological samples was carried out in 2006-2008 by the Non-Human Forensic Genetics Commission of the Spanish and Portuguese Working Group (GEP) of the International Society for Forensic Genetics (ISFG). The participating laboratories were asked to sequence two dog samples (one bloodstain and one hair sample) for the mitochondrial D-loop region comprised between positions 15,372 and 16,083 using suggested primers and PCR conditions, and to compare their results against a reference sequence. Twenty-one participating laboratories reported a total of 67.5% concordant results, 15% non-concordant results, and 17.5% no results. The hair sample analysis presented more difficulty to the participants than the bloodstain analysis, with a high percentage (29%) failing to obtain a result. The high level of participation showed the interest of the community in the analysis of dog forensic samples but the results reveal that crucial methodological issues need to be addressed and further training is required in order to respond proficiently to the demands of forensic casework.

Identificación de sospechosos a través de búsquedas familiares en la base de datos de ADN de interés criminal. Implicaciones sociales, éticas y científicas / Suspects identification through 'familial searching' in DNA databases of criminal interest. Social, ethical and scientific implications

El uso de la tecnología del ADN ha revolucionado la ciencia forense en los últimos años, convirtiéndose en una herramienta de incalculable valor en los procesos de investigación e identificación forense. Además, la creación de bases de datos de perfiles genéticos de ADN ha permitido relacionar de manera eficiente personas y escenas del delito. La búsqueda familiar es una estrategia importante que permite establecer relaciones familiares entre el perfil genético hallado en la escena del delito, y objeto de la investigación, y eventuales familiares que pudieran encontrarse en dicha base de datos. Esta identificación de potenciales familiares puede permitir la identificación de la persona desconocida y la resolución del hecho delictivo. Esta estrategia de investigación cuenta con impulsores y detractores en relación con su utilización en el ámbito legal, social, ético y científico. El presente artículo revisa todos estos aspectos y aporta una visión general de la situación actual (AU)

In recent years, DNA technology has revolutionised forensic science, becoming an invaluable tool in the investigation and forensic identification processes. Moreover, the creation of DNA databases has allowed to efficiently link people and crime scenes. Familial searching is an important strategy for establishing family relationships between the genetic profile at the centre of the investigation, found at the crime scene, and any family members who might be in the database. This identification of potential relatives can lead to identification of the unknown person and the crime being solved. In the legal, social, ethical and scientific fields, this investigation strategy has both promoters and detractors regarding the effectiveness of its use. This article aims to review all these aspects and provide an overview of the current situation (AU)

Identificación de restos cadavéricos: casuistica en el periodo comprendido entre 1999 y 2001 / Identification of human remains: casework between 1999 and 2001

En este trabajo se presenta la casuística relacionada con identificación de restos cadavéricos que durante el periodo comprendido entre 1999 y 2001 se llevó a cabo en nuestro laboratorio. Se recibieron 122 restos cadavéricos para identificar de los cuales se dispuso de muestras de referencia de familiares en el 50 por ciento de los casos. Hemos empleado tanto análisis de ADN nuclear (71 por ciento) como análisis de ADN mitocondrial (20 por ciento) para llevar a cabo dichas identificaciones (AU)

Validación del sistema DNA IQ para su uso en genética forense / Validation of the DNA IQtm systems for forensic casework

El propósito de este trabajo fue evaluar el nuevo kit de extracción con fines forenses de Promega DNA IQ. Para ello se emplearon diferentes muestras de las que habitualmente llegan a un laboratorio forense, encontrándose en todos los casos un resultado satisfactorio (AU)

Determinación del volumen de sangre en manchas de sangre sobre ropas / Blood volume determination from blood stains on clothes

La muerte por choque hipovolémico tiene lugar cuando el volumen de sangre perdido alcanza aproximadamente un tercio del volumen total contenido en un adulto. Ropas y otros objetos manchados de sangre fueron hallados en un coche y remitidos a nuestro laboratorio. El objetivo del análisis era la investigación tanto de la entidad como de la cantidad de la sangre existente en ropas y objetos con el fin de determinar si dicha cantidad de sangre era suficiente como para haber causado la muerte a la supuesta víctima (AU)