RESUMO
We report the results of the seventh edition of the GEP-ISFG mitochondrial DNA (mtDNA) collaborative exercise. The samples submitted to the participant laboratories were blood stains from a maternity case and simulated forensic samples, including a case of mixture. The success rate for the blood stains was moderate ( approximately 77%); even though four inexperienced laboratories concentrated about one-third of the total errors. A similar success was obtained for the analysis of mixed samples (78.8% for a hair-saliva mixture and 69.2% for a saliva-saliva mixture). Two laboratories also dissected the haplotypes contributing to the saliva-saliva mixture. Most of the errors were due to reading problems and misinterpretation of electropherograms, demonstrating once more that the lack of a solid devised experimental approach is the main cause of error in mtDNA testing.
Assuntos
Artefatos , Técnicas de Laboratório Clínico/normas , Impressões Digitais de DNA/normas , DNA Mitocondrial/genética , DNA/isolamento & purificação , Manchas de Sangue , Simulação por Computador , DNA/análise , DNA/genética , DNA Mitocondrial/sangue , DNA Mitocondrial/química , Interpretação Estatística de Dados , Bases de Dados Factuais , Feminino , Medicina Legal , Marcadores Genéticos , Cabelo/química , Haplótipos , Humanos , Filogenia , Reação em Cadeia da Polimerase , Polimorfismo Genético , Gravidez , Controle de Qualidade , Padrões de Referência , Saliva/químicaRESUMO
Since 1992 the Spanish and Portuguese Working Group (GEP) of the International Society for Forensic Haemogenetics (ISFH) has been organizing collaborative exercises on DNA profiling with the aim of making progress on standardization and discussing technical and statistical problems in DNA analysis. A total of four exercises (GEP-92 to GEP-95) have been carried out until now. A consequence of these exercises was the creation of a quality control programme in Spain and Portugal in 1995 which was carried out simultaneously with the GEP-95 exercise. The number of participating laboratories increased from 10 in the first exercise (GEP-92) to 19 in the last exercise (GEP-95). Despite this increasing number of participating laboratories, results remained satisfactory. In the last exercises, all the laboratories used PCR-based DNA polymorphisms with an increasing number of markers obtaining good results. SLPs were used by only 30% of laboratories in the last two exercises but the results indicated a good level of expertise in most of these laboratories. The reasons for these successful results are the common use of the EDNAP protocol for SLP analysis and commercially available kits or common sequenced allelic ladders for PCR-based DNA polymorphisms.
