Technical Note

REFERENCE: LaFountain M, Schwartz M, Cormier J, Buel E. Forensic samples offer a challenge to nearly any analytical Validation of capillary electrophoresis for analysis of the X-Y method. Sample age or origin may be undetermined and available homologous amelogenin gene. J Forensic Sci 1998;43(6): sample volume small. Material submitted for testing may be depos1188–1194. ited on any imaginable surface, or it may be incidentally or intentionally contaminated or obliterated. Biological material brought ABSTRACT: Capillary electrophoresis (CE) is a versatile technolto the forensic lab may have come from more than one individual. ogy with tremendous potential applications in forensic science. A refinement of the traditional slab-gel, separation occurs in a liquid Additionally, the outcome of forensic testing can have serious conpolymer contained within a capillary. The capillary electrophoresis sequences within the criminal justice system. With these consideraunit is computer-driven, semi-automating the loading and analysis tions in mind, validation of methods or instrumentation for forensic of samples. employment must be rigorous using samples comparable to those As with any new technology, a full performance assessment is required before it may be implemented with confidence. This paper found in the field. focuses on validation of CE technology for analysis of a portion The X-Y homologous amelogenin gene codes for an integral of the X-Y homologous amelogenin gene used in gender determinaprotein in mammalian tooth enamel development (4). It has been tion. Typical Y/X ratios of peak heights for male samples were studied in a number of species, and large areas in both the coding determined. Instrument linearity, sample resolution and reproducand non-coding regions of the gene have been found to be conibility were examined. Samples subjected to contamination, extreme environmental conditions or extracted from a variety of substrates served throughout evolution (5–9). This gene has been used extenwere also tested by CE. All samples typed correctly. Genetic matesively for sex-typing of forensic materials (10–13). Amplification rial from a number of common non-primate animals was amplified of a small portion of the human amelogenin gene produces distinct with amelogenin primers. Some species yielded no product. Prodfragments from the X and the Y chromosomes and consequently, ucts derived from the animal samples that did amplify produced peaks on CE analysis readily distinguishable from those of human information regarding the gender of the DNA donor (14–16). Since origin. the sequence required for amplification is relatively small, even highly degraded DNA may yield typeable results.