Abstract
BackgroundDisaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences, and subsequent DNA typing is essential. Collected samples for DNA-based human identification are usually stored at low temperature to halt the degradation processes of human remains. We have developed a simple and reliable procedure for soft tissue storage and preservation for DNA extraction. It ensures high quality DNA suitable for PCR-based DNA typing after at least 1 year of room temperature storage.MethodsFragments of human psoas muscle were exposed to three different environmental conditions for diverse time periods at room temperature. Storage conditions included: (a) a preserving medium consisting of solid sodium chloride (salt), (b) no additional substances and (c) garden soil. DNA was extracted with proteinase K/SDS followed by organic solvent treatment and concentration by centrifugal filter devices. Quantification was carried out by real-time PCR using commercial kits. Short tandem repeat (STR) typing profiles were analysed with 'expert software'.ResultsDNA quantities recovered from samples stored in salt were similar up to the complete storage time and underscored the effectiveness of the preservation method. It was possible to reliably and accurately type different genetic systems including autosomal STRs and mitochondrial and Y-chromosome haplogroups. Autosomal STR typing quality was evaluated by expert software, denoting high quality profiles from DNA samples obtained from corpse tissue stored in salt for up to 365 days.ConclusionsThe procedure proposed herein is a cost efficient alternative for storage of human remains in challenging environmental areas, such as mass disaster locations, mass graves and exhumations. This technique should be considered as an additional method for sample storage when preservation of DNA integrity is required for PCR-based DNA typing.
Highlights
Disaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences, and subsequent DNA typing is essential
In order to test the efficiency and reliability of sodium chloride as a soft tissue preservation method leading to recovery of DNA samples suitable for polymorphic loci analysis, human psoas muscle was exposed to three different preservation conditions at different storage times over a 1-year period
Muscle samples of similar weight maintained at room temperature were exposed to solid sodium chloride, garden soil, or were left untreated
Summary
Disaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences, and subsequent DNA typing is essential. We have developed a simple and reliable procedure for soft tissue storage and preservation for DNA extraction. It ensures high quality DNA suitable for PCRbased DNA typing after at least 1 year of room temperature storage. Disaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences. This complex task is usually approached within a multidisciplinary context [1,2,3,4]. Several specific methods for specimen preservation have been described, some of which exhibit adequate storage capacity for different tissues, for example, cryopreservation [7], formalin-fixed paraffin-embedded tissue, despite producing the disadvantage of irreversible changes in the molecular structure [9,11], salt water [10], alcohol-based tissue fixatives, dimethylsulfoxide (DMSO), commercial kits such as the Oragene DNA self-collection kit (DNA Genotek, Ottawa, Ontario, Canada) [11,12,13,14], LST buffer [12], and RNAlater (Ambion, Austin, TX, USA) [13]
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