Study On The Application Value Of16STR Loci On X Chromosome For Kinship Analysis

By investigating the polymorphism of16X-STR loci (GATA165B12, DXS101,GATA172D05, HPRTB, DXS981, DXS8378, DXS6795, GATA31E08, DXS6809,DXS6803, DXS9902, DXS6807, DXS7423, DXS7133, DXS6810, DXS7132) amongChinese Han, Uygur, Hui, Tibet and Mongo population, contrasting the allelefrequency differences, testing the linkage disequilibrium, evaluating the systemefficiency, analyzing the actual mutation rate and exclusion rate, applying the panelX-STRs to complex cases, the special application value of16X-STR loci wasconfirmed. The results of the research could provide theoretical basis for calculationand analysis of X-STR loci likelihood ratio, and made up for the shortcomings ofcurrent research about X-STR loci in China.This article was divided into four chapters. By analyzing the16X-STR locigenotyping results in multi-ethnic unrelated individuals and detecting of16X-STRloci in duos and trios, the genetic parameters and the actual mutation rates werecalculated. Linkage disequilibrium was analyzed. Furthermore, the system efficienciesand practical value in cases were evaluated.In Chapter one, the research progress and states of detection methods about Xchromosomal STR markers in China and some other countries were introduced and the incomparable value of X-STR loci was elaborated. Moreover, the problems andconcerns about application of X-STRs were pointed out.In Chapter two, the polymorphisms of16X-STR loci were investigated. Theresults proved that the allele frequencies of16X-STR loci among Chinese Han,Uygur, Hui, Tibet and Mongo population did not deviate from the laws ofHardy-Weinberg equilibrium and the16X-STR loci were polymorphic in the abovepopulations with ideal genetic parameters suitable for forensic application. Bycontrasting the allele frequency differences of16X-STR loci among abovepopulations, it was indicated that the distributions of the alleles of16X-STR loci hadnational differences which meant that a set of data about allele frequencies in onepopulation should not be unsuitable used for other kind of nationality. After analyzingtwo-locus linkage disequilibrium, it was found that all the values of|D’|were less than0.2and r2were less than0.02which indicated linkage disequilibrium did not exist inthe panels of X-STRs.In Chapter three, the system efficiency of16X-STR loci was evaluated. Theresults showed that both cumulative discrimination power and cumulative probabilityof exclusion among Chinese Han, Uygur, Hui, Tibet and Mongo population couldmeet forensic science application requirements well. The above results proved that thepanel of X-STRs could play a vital role in parentage testing andindividual identification. Furthermore, it could become a useful tool for difficultrelationship testing cases.In Chapter four, some typically complex cases about kinship analysis wereenumerated. It was showed that the X-STR markers needfully supplemented the useof autosomal STR loci and had considerable potential to aid identification.