| Objective The purpose of this project is to establish the fluorescent Multiplex X-STR system of DXS9902,DXS6800,DXS6799 and DXS7132.And validate the forensic application of this multiplex system.To provide the evidence through our typing system for population genetics by investigating its polymorphism in the Han population lived in Beij ing.Method Select DXS9902,DXS6800,DXS6799 and DXS7132,with good polymorphisms and high Discriminate Probability from the eight loci that have been reported in internal and abroad. And then begin the research of this fluorescent multiplex system using the traditional multiplex methods.Four X-STR loci were amplified and the products of the multiplex PCR were genotyped by ABI PRISM 3100 Genetic Analyzer.The multiplex X-STR system was evaluated the sensitivity,accuracy and different PCR outcome under different amplification parameter. Validation study of Forensic Science included species specificity,tissular identity and performance of forensic case.A total of 200 male and 200 female individuals from unrelated Beijing Han population were tested using this system.Result Successfully establish the fluorescent multiplex system of DXS9902,DXS6800,DXS6799 and DXS7132.Moreover,the condition of system is stabile.We can get the satisfied analytic result and it is higher performance.Validation study of Forensic Science shows that the sample sensitivity of this system is 0.25ng template DNA,and the four loci'S species specificity (pig,COW,sheep,cock,fish and duck)and tissular(blood,skeletal muscle,heart muscle,liver,lung and brain of the same man)identity is good.And the utilization of forensic cases,for example rib,salivary stain,testicular fluid and hair,proves the application of this system in forensic individual identification and paternity test.By investigating its polymorphism in the Han population lived in Beij ing,forensic parameters of the four X-STR loci were obtained.The allele frequencies distribution is from 0.002 to 0.817;The discrimination power is from 0.526t00.886;The expected probability of exclusion is from 0.32 to 0.691 and independence analysis shows no Linkage disequilibrium between the four X-STR.Conclusion The multiplex system of DXS9902,DXS6800,DXS6799 and DXS7132 can be successfully used in the ABI PRISM 3100 detection platform and can get the reliable genotype. The forensic genetics research implies that it is an easily-operated and high efficient multiplex system with stable outcome,high sensitivity,accuracy,tissular identity and good species specificity.This method can be used conveniently and extensively.Population investigation shows chis system is high discrimination power and probability of exclusion and the four X-STR are independent each other.It could be recommended to the forensic genetics practice. |
