| Trace forensic materials is one of the challenges the forensic science is facing, and how to get more information from them has always been the orientation of the forensic working.With the emergence of whole genome amplification technology and the development of single-cell sequencing technology, the trace problem was simplified and effectively solved. As an significant genetic phenotypes of human, ABO blood typing has been widely employed in forensic cases. The accurate typing results were collected with the help of traditional serological method. Furthermore, based on the mutation in ABO gene, the DNA typing technology was constructed and remarkably improved. The combination of the two technologies, can not only solve the problem of trace forensic materials, but also can provide the phenotype-related information, consequently, offers certain help for the police to trace the criminal suspects.Individual identification from genetic markers were often used in the field of criminal cases cracking, the judicial trial and forensic paternity identification. In most actual cases of forensic DNA testing, the forensic materials from the criminal site always decayed, sometimes even badly decayed.In such forensic materials, the DNA molecules vere damaged since the double strands broke up and the integrity of DNA were disrupted. With the progress of the judicial practice, the requirement of forensic evidences has become more demanding, requiring the DNA tests to provide more information. Some significant technical problems emerged when the forensic researchers applied the STRs genotyping, such as gene leakage and advantage amplification, so these problems will affect the final genotyping results and cause great difficulties to forensic application.As the third generation of genetic markers, SNPs is characterized by wide distribution, low mutation rate, genetic stability and high throughput automatic analysis.What is more, it is beneficial to the degraded and trace forensic materials because of short amplifying fragment length and nonexistence of replication slippage. With further investigation, SNPs got more and more attentions in forensic area. With the constructive cooperations and efforts between many geneticists and anthropologists, they made a profoud and comprehensive research on genetic mutation for human phenotypes such as pigmentation and craniofacial development by the combination of sequencing and genome-wide association study in terms of human evolution and migration history, thus to construct the individual identification panel to predict the traits of suspects. With the construction of SNPs genotyping for individual identification and phenotype prediction, a new era of "intelligent DNA" was launched.In the thesis, we extracted the trace fingerprint exfoliated cells by sweat latent fingerprints extraction reagent which was independently developed in our laboratory(No.200810233535.8), then, applied. the whole genome amplification technology to amplify the trace DNA, and genotyped the ABO blood by six SNPs located in ABO gene through SNaPshot technology. Firstly, we applied the ABO genetyping by SNaPshot technology to trace materials field, then, the method was optimized by experimental processes. Secondly, we collected48fingerprint epithelial exfoliated cells samples and48oral swabs samples were collected as the positive control at the same time. All of the48samples were genotyped by the optimized method. The48fingerprint epithelial exfoliated cells samples were detected, and47oral swabs samples were tested (No.32samples of oral swab was lost due to operatin errors in the process). The detection results for the47samples from the describe two origins can be exactly matched. At the same time, the genotyping results were consistent with serological results, suggesting the optimized method can be applied and genotyped to trace DNA effectively, and offer a potential means to crack criminal cases. |
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