Centro de Documentação da PJ
Monografia
 CD258 |
DNA assay development and validation for pigment-related features to assist in the identification of missing persons and human remains [Documento electrónico] : final technical report / Elisa Wurmbach.- [Rockville, MD] : National Criminal Justice Reference Service (NCJRS), 2013.- 1 CD-ROM ; 12 cm
Research report submitted by New York City Office of Chief Medical Examiner to the U.S. Department of Justice, NIJ - Forensic DNA Unit Efficiency Improvement Program. Award Number 2010-DN-BX-K181. Ficheiro de 1,34 MB em formato PDF (53 p.).
ADN, IDENTIFICAÇÃO DE CADÁVER, PESSOA A PROCURAR, DESAPARECIMENTO DE PESSOAS
An essential component in identifying human remains is documenting the decedent’s visible characteristics, such as eye, hair and skin color. However, if a decedent is decomposed or only skeletal remains are found, this critical, visibly identifying information is lost. It is presently not possible to use genetic information to reveal these visible characteristics in detail. The objectives of this project were to design and validate an assay to predict eye and skin color based on DNA to assist in the identification of missing persons and human remains. This assay increases the amount of information available for the identification of unknown decedents. Genetic differences that account for broad variations in individuals’ visible traits can be utilized to identify molecular markers, which then in turn can be used to confirm or predict such traits. The variety of phenotypes is caused by multiple polymorphisms in genes of which some are involved in the pigmentation process. The simplest kind of polymorphism is the single nucleotide polymorphism (SNP), and assessing those can reveal visible characteristics of unidentified decedents. Since there are thousands of SNPs, it is challenging to find those few which are directly responsible for a person’s eye, hair and skin color. Association studies including genome-wide SNP-scans have pointed to a few genes relevant for eye, hair, and skin pigmentation. Recent studies identified candidate-SNPs that correlate with high significance to blue and brown eye color, and more SNPs were found to correlate with light skin coloration of East Asians and Europeans and darker complexion of African-Americans. Validation of these SNPs on over 600 samples from individuals of various populations identified seven SNPs located in or nearby pigmentation genes that can be used to describe the eye and skin color solely based on DNA. Five of the seven SNPs are potentially causative: three cause missense mutations and two SNPs are directly located in predicted transcription factor binding sites. The other two SNPs are located in introns and it is still unclear whether they are causative. Six of the seven SNPs are used to predict the eye color, which distinguishes among brown, green, not blue (green or brown), and not brown (green or blue). All seven SNPs are used to make predictions of the skin coloration of individuals, distinguishing between not white (light brown or dark) and not dark (light brown or white). Both tests can be applied to various populations including African-American, East Asian, South Asian, European and mixed populations. The error-rates for both predictors are very low: 3% for the eye color predictor and 1% for the skin color predictor. Just recently, the seven-plex system was improved by adding one SNP (rs12896399, which is located in the 5’-region of SLC24A4) and by changing the instructions (Hart, Kimura et al. 2013). More precise predictions were achievable by including blue to the eye colors: brown, green, not blue and not brown, and light to the skin colors: not dark and not light. The number of positive descriptions was also significantly increased, while keeping the error rates low, at approximately 5% (Hart, Kimura et al. 2013). These eight SNPs were integrated into a forensic kit that is easy, fast and inexpensive. This test has potential for upgrading. A multiplex-SNP-assay fitting these criteria would involve a multiplex PCR followed by a multiplex primer extension reaction leading to fluorescently labeled oligonucleotides of distinct length. Multicolor capillary electrophoresis separates and detects these oligonucleotides. It is possible to apply this assay on degraded DNA (typically found in decomposed human remains) due to the design of small PCR products. This is important for forensic applications. Furthermore, development and validation were cost-efficient since all required equipment including the software was already available in-house. The utilization of this multiplex-SNP-assay to predict pigment-related features will greatly enhance current efforts of collecting data from human remains to facilitate identification. It may be incorporated into the Office of Chief Medical Examiner DNA Missing Persons Group and the Forensic Anthropology Unit’s multidisciplinary effort to reduce the number of unidentified human remains in New York City and New York State.