Molecular Forensic Pathology

Abstract

DNA methods have revolutionized the science of human identification. DNA profiling has been particularly useful in the identification of criminals, especially in rape and murder cases as well as in the assessment of parentage/paternity. Previous to DNA identification methods, blood groups and protein polymorphisms were used. In general, they were not very discriminatory. They also required a relatively large sample of blood and had extremely limited usefulness in tissue identification. This chapter briefly covers some history of the development of DNA methods of human identification. It reviews issues/steps prior to the actual DNA analysis such as sample collection and preservation, chain of custody, and DNA isolation/extraction. Because many DNA analysis methods are PCR-based, there is some discussion of the basic procedure of PCR as well as of limitations and other considerations about this technique. Much of the chapter is focused on technical (lab bench work) and calculation aspects of STR (short tandem repeat) marker analysis. This includes a discussion of the analysis of genotype results and the use/importance of population databases, an example calculation of a profile frequency as may be applied to a forensic case, and the use of STR marker results in parentage/paternity testing.