DNA investigation on human bones: results, potentialities and limits - a five year report

Abstract

Solving cases of DNA identification on human bone remains is a difficult task for the forensic genetic experts. In order to succeed in this attempt, they have to develop and optimise specific laboratory protocols. This paper is a five year retrospective study which presents our lab results regarding the genetic identification on bone samples using various extraction methods and PCR protocols. Methods: 50 bone samples were investigated after cryogenic pulverization by four types of DNA extraction protocols and several commercial STR-PCR kits. Some of the samples were analysed using one or more protocols, depending of the case nature or of the specific working conditions available at the moment of the investigation. The quantity and quality of all DNA extracts was evaluated with a real-time method, while PCR products detection was performed on an ABI PRISM (R) 3100Avant Genetic Analyzer. Results: The selection and optimisation of both DNA extraction and genotyping protocols have increased our success rate from 0% in 2004 to 56% in 2008, best results being obtained for compact bones, especially femur samples. The increase of DNA bone extracts quantity and quality was generally achieved by combining the lab procedures. For all the investigated cases, the DNA isolation step proved to be critical for a successful typing. Conclusions: A careful and continuous selection and optimization of the DNA isolation protocols greatly increased our success rate for different bone types, allowing us to positively identify skeletal remains. The reported results on bone samples recommend the reconsidering of role of DNA investigation on human bone samples in the framework of our national identification protocols that operate either for missing persons, crime victims or mass disasters