DNA recovery and analysis from skeletal material in modern forensic contexts

Abstract

The generation of a DNA profile from skeletal remains is an important part of the identification process in both mass disaster and unidentified person cases. Since bones and teeth are often the only biological materials remaining after exposure to environmental conditions, intense heat, certain traumatic events and in cases where a significant amount of time has passed since the death of the individual, the ability to purify large quantities of informative DNA from these hard tissues would be beneficial. Since sampling the hard tissues for genetic analysis is a destructive process, it is important to understand those environmental and intrinsic factors that contribute to DNA preservation. This will serve as a brief introduction to these topics, since skeletal sampling strategies and molecular taphonomy have been discussed in depth elsewhere. Additionally advances in skeletal DNA extraction and analysis will be discussed. Currently there is great variation in the DNA isolation methods used by laboratories to purify DNA from the hard tissues; however, a standardized set of short tandem repeat (STR) loci is analyzed by many US laboratories to allow for comparisons across samples and jurisdictions. Recent advances have allowed for the generation of DNA profiles from smaller quantities of template DNA and have expanded the number of loci analyzed for greater discriminatory power and predictions regarding the geographic ancestry and phenotype of the individual. Finally, utilizing databases and expanding the number of comparison samples will be discussed in light of their role in the identification process.

A systematic investigation of human DNA preservation in medieval skeletons

“…Teeth have been widely used for the study of aDNA 36 , 37 , though the 30-fold covered genome of an archaic hominin from Denisova Cave from a distal phalanx demonstrates molecular preservation in elements that are not typically considered for paleogenetics work 4 . Despite these successes, a systematic and extensive study of differential DNA preservation across multiple human skeletal elements, such as those done in the context of modern forensics 38 , 39 , has yet to be attempted on archaeological remains. Our limited understanding of DNA preservation across the human skeleton is a significant hurdle for the efficient, practical, and ethical study of aDNA, which has particular relevance to the field of ancient population genetics where large sample sizes are needed for robust analytical resolution.…”

A systematic investigation of human DNA preservation in medieval skeletons

“…Teeth have been widely used for the study of aDNA 33,34 , though the 30-fold covered genome of an archaic hominin from Denisova Cave from a distal phalanx demonstrates molecular preservation in elements that are not typically considered for paleogenetics work 4 . Despite these successes, a systematic and extensive study of differential DNA preservation across multiple human skeletal elements, such as those done in the context of modern forensics 35,36 , has yet to be attempted on archaeological remains. Our limited understanding of DNA preservation across the human skeleton is a significant hurdle for the efficient, practical, and ethical study of aDNA, which has particular relevance to the field of ancient population genetics where large sample sizes are needed for robust analytical resolution.DNA preservation can be influenced by many factors including burial practises and treatment of the deceased, geology, as well as environmental and climatic conditions 37 , where the chronological age of a sample is thought to play only a secondary role 38,39 .…”

Recent trends and developments in forensic DNA extraction

“…With decomposition over time or damage from heat (such as fire), the laboratory may also be faced with processing more difficult samples such as teeth and bones. In such samples, the DNA is chemically linked to the hydroxyapatite mineral matrix keeping it well protected, but at the same time necessitating prolonged and intensive pre‐processing of samples prior to DNA extraction (Brundin, Figdor, Sundqvist, & Sjögren, 2013; Latham & Miller, 2019). With man‐made disasters, be it accidents or acts of terror, casework samples may be contaminated with chemical, biological, or radiological (CBR) agents.…”