The Use of Forensic DNA Phenotyping in Predicting Appearance and Biogeographic Ancestry

Abstract

he legalization of forensic DNA phenotyping has been publicly debated in Germany and Switzerland in the past few years while the technology has already been implemented in a few other countries. Forensic DNA phenotyping goes beyond standard forensic DNA profiling, where short tandem repeat (STR) polymorphisms are used to identify individuals from DNA obtained at crime scenes and other DNA markers are used for sex determination. In more novel forensic DNA phenotyping, however, information from crime scene DNA about externally visible characteristics and biogeographic ancestry (i.e., the inferred geographic region(s) of origin of a person's biological ancestors) are collected. Estimating a person's age from DNA found at the crime scene is also part of forensic DNA phenotyping and is currently debated as well, but will only be peripherally considered in this review, as it differs from the other two types of forensic DNA phenotyping in its scientific, including molecular, basis, analytical methods, and sample requirements (Box). Genetic diseases and their predispositions are excluded from forensic DNA phenotyping, as it is held that their forensic use would disproportionately violate privacy. The public debate about the legalisation of forensic DNA phenotyping arose after many years of research into the genetic basis of physical appearance and the genetic correlates of biogeographic ancestry, followed by the development of suitable analytical techniques that could be used forensically for the DNAbased prediction from human biological samples obtained at crime scenes (1, 2, 3). Such DNA test systems are needed because of the general limitations of forensic STR-profiling. The latter can only yield an individual identification by a direct comparison of the crime-scene STR-profile with the STR-profile of a suspect in the case, or of a person whose STR-profile is stored in a nationwide forensic DNA database (e.g, the DNA database of the Federal Criminal Police Office [Bundes kriminalamt], the German counterpart to the F.B.I.). Positive identification is possible only if there is a match, i.e., absolute agreement of the STRprofile of the crime scene sample with that of a known person. In criminal cases without a STR-profile match, forensic DNA phenotyping can be a helpful Summary Background: Persons whose identifying DNA profile (STR profile) is not yet known to the ingvestigating authorities cannot be identified by standard forensic DNA analysis (STR profiling) as it is now practiced. In view of the current public debate, particularly in Germany, on the legalization of so-called forensic DNA phenotyping, we present its scientific basis, societal aspects, and forensic applications and describe the analytic techniques that are now available. Methods: This review is based on pertinent publications that were retrieved by a selective search in PubMed and in public media, and on the authors' own research. Results: Forensically validated DNA test systems are available for the categorization of eye, hair, and skin color and the i...

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