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Validação do método de extração Casework Direct Kit em amostras forenses
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A criminalística biológica tem como principal objetivo identificar o(s) autor(es) do crime,
visando a comparação dos perfis genéticos das amostras da vítima e do arguido (amostras
de referência) com os perfis genéticos das amostras alusivas ao crime (amostras
problema).
Os tipos de materiais biológicos mais analisados em contexto forense são sangue, sémen,
saliva e pelos, sendo que, regularmente estas amostras apresentam um determinado grau
de degradação. Assim sendo, é fulcral existirem métodos robustos, capazes de obter perfis
genéticos suficientemente discriminativos.
O laboratório do Serviço de Genética e Biologia Forenses - Delegação do Sul (SGBF-S),
do Instituto Nacional de Medicina Legal e Ciências Forenses, I.P. (INMLCF, IP.), é um
laboratório acreditado. Para tal, este tem que demonstrar que mantém boas práticas
laboratoriais nomeadamente o cumprimento da cadeia de custódia e o cumprimento de
todos os procedimentos envolvidos na análise de amostras forenses
A validação dos procedimentos realizados no SGBF-S é realizada segundo os preceitos
descritos na norma internacional de referência NP EN ISO/IEC 17025:2018.
O Casework Direct Kit foi recentemente desenvolvido com a finalidade de obter
rapidamente lisados de DNA, a partir de amostras forenses, principalmente zaragatoas e
tecidos manchados provenientes de casos de agressão sexual e criminais, sem a
necessidade de purificação prévia.
Este kit demonstrou ser adequado na análise de amostras forenses, usando os marcadores
genéticos utilizados na rotina dos casos forenses do SGBF-S.
Foi possível obter concentrações mínimas de DNA nos valores de 0,0007ng/μL e
concentrações máximas de DNA nos valores de 15,28ng/μL, mostrando, assim, elevado
grau de sensibilidade. Adicionalmente, revelou repetibilidade e reprodutibilidade e
capacidade para diferenciar perfis masculinos e femininos em amostras com pouco DNA.
O método está validado e será implementado na rotina dos casos criminais do SGBF-S.
The main objective of biological criminalistics is to identify the perpetrator(s) of the crime by comparing the genetic profiles of the samples of the victim and the accused (reference samples) with the genetic profiles of the crime-related samples (problem samples). The types of biological materials most commonly analyzed in forensics are blood, semen, saliva and hair, and these samples regularly show a certain degree of degradation. Therefore, it is essential to have robust methods capable of obtaining sufficiently discriminative genetic profiles. The laboratory of the Service of Forensic Genetics and Biology - Southern Delegation (SGBF-S), of the National Institute of Legal Medicine and Forensic Sciences, I.P. (INMLCF, IP), is an accredited laboratory. To do so, it has to demonstrate that it maintains good laboratory practices, namely the compliance with the chain of custody and the fulfillment of all procedures involved in the analysis of forensic samples. The validation of the procedures performed at the SGBF-S is performed according to the precepts described in the international reference standard NP EN ISO/IEC 17025:2018. Casework Direct Kit was recently developed for the purpose of rapidly obtaining DNA lysates, from forensic samples, mainly swabs and stained tissues from sexual assault and criminal cases, without the need for prior purification. This kit proved to be suitable in the analysis of forensic samples using the genetic markers used in routine SGBF-S forensic cases. It was possible to obtain minimum DNA concentrations at values of 0.0007ng/μL and maximum DNA concentrations at values of 15.28ng/μL, thus showing a high degree of sensitivity. Additionally, it showed repeatability and reproducibility and the ability to differentiate male and female profiles in samples with low DNA. The method is validated and will be implemented in the routine of criminal cases at SGBF-S.
The main objective of biological criminalistics is to identify the perpetrator(s) of the crime by comparing the genetic profiles of the samples of the victim and the accused (reference samples) with the genetic profiles of the crime-related samples (problem samples). The types of biological materials most commonly analyzed in forensics are blood, semen, saliva and hair, and these samples regularly show a certain degree of degradation. Therefore, it is essential to have robust methods capable of obtaining sufficiently discriminative genetic profiles. The laboratory of the Service of Forensic Genetics and Biology - Southern Delegation (SGBF-S), of the National Institute of Legal Medicine and Forensic Sciences, I.P. (INMLCF, IP), is an accredited laboratory. To do so, it has to demonstrate that it maintains good laboratory practices, namely the compliance with the chain of custody and the fulfillment of all procedures involved in the analysis of forensic samples. The validation of the procedures performed at the SGBF-S is performed according to the precepts described in the international reference standard NP EN ISO/IEC 17025:2018. Casework Direct Kit was recently developed for the purpose of rapidly obtaining DNA lysates, from forensic samples, mainly swabs and stained tissues from sexual assault and criminal cases, without the need for prior purification. This kit proved to be suitable in the analysis of forensic samples using the genetic markers used in routine SGBF-S forensic cases. It was possible to obtain minimum DNA concentrations at values of 0.0007ng/μL and maximum DNA concentrations at values of 15.28ng/μL, thus showing a high degree of sensitivity. Additionally, it showed repeatability and reproducibility and the ability to differentiate male and female profiles in samples with low DNA. The method is validated and will be implemented in the routine of criminal cases at SGBF-S.
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Ciências biomédicas Microbiologia Biologia molecular