| Objective The aim of this research was to study the genetic polymorphism of20autosomal STR loci in PowerPlex21detection system in Han population of Fujianprovince, to evaluate its forensic application. In addition,the study also aimed to comparegenotype of unrelated individuals for clarifing the probabitity of in agreement withMendel,s law in15STR loci and20STR loci after autosomal STR database wasestablished,and to provide basis for the standardization of forensic duo paternity test andensuring accurate and scientific identification results.Methods⑴Collecting the EDTA-sample of850unrelated individuals of Han population inFujian. Using PowerPlex21fluorescent compound amplification system kit, PCRamplification technique, capillary electrophoresis and fluorescence detection technology toseparate and genotype. The heterozygosis(H)，power of discrimination(PD),polymorphisminformation content（PIC）, probability of paternity exclusion（PE） and matchingProbability（PM) were calculated by Modified-powerstates software．The exact test of theHardy-Weinberg equilibrium was also performed．⑵Base on DNA blind comparison technology of paternity testing matching software,Input all material and STR loci information of13576unrelated individuals to establishautosomal STR database consisiting of Identifiler (ID), Sinofiler (SINO), PowerPlex16(PP16), PP21detection system.⑶Randomly select721cases in PP21detection system, using the DNA blindcomparison technology of paternity testing matching software to compare the genotypebetween the above cases and unrelated individuals，to do statistic analysis of the probability of15STR locus and20STR locus in agreement with Mendel,s law, calculate the CPI andRCP in78cases of hypothetical duo paternity test.⑷For15STR loci in agreement with Mendel,s law of hypothetical duo paternity, adddetecting PP21detection system. Investigator HD plex and Investigator Argus X-12detection system are used for unexcluded in15STR loci detection system and20STR lociin agreement with Mendel,s law of hypothetical duo paternity in PP21detection system.Results⑴20autosomal STR loci in PowerPlex21detection system were in agreement with theHardy-Weinberg-equilibrium(p>0．05)，257kinds of alleles were found in Han populationof Fujian province. The average heterozygosis was calculated as0.797, polymorphisminformation content was above0.5, power of discrimination(PD) was above0.9,except forCSF1PO（0.893）、TPOX（0.772）、TH01（0.848）、D3S1358（0.873）.The heterozygosis(H)was above0.7except for TPOX（0.594）、TH01（0.667）.⑵24kinds of off-ladder （OL） alleles in PP21detection system were found in Hanpopulation of Fujian province, with the occurrences ranging from1to13times and theallelic frequencies ranging from0.0006to0.0076，13kinds of OL genes were the firstreport.(3) An autosomal STR database with13576unrelated individual STR loci informationwere established. Randomly select721individuals,387individuals who matched withunrelated individuals at15STR loci,4of387individuals who matched with unrelatedindividuals at20STR loci. The matching probability of15STR loci is2.85%, and thematching probability of20STR loci is0.57%。(4) In78cases of hypothetical duo paternity, the minimum and maximum CPI were7.67(RCP>88.46%),258602.95(RCP>99.99%) respectively,10cases could not be excluded.By adding STR loci from PP21、Investigator HD plex and Investigator Argus X-12detection system, the number of exclusion locus was from3to15， all the above caseswere excluded. Conclusions⑴The distribution of20STR loci in PP21detection system fitted Hardy-weinberg balancein Fujian Han population, had high power of discrimination,probability of exclusion, canprovide a high forensic application.⑵It is suggested that autosomal STR database construction should apply the detectionsystem containing20STR locis. It is better to apply the detection system containing fewchromosome STR locs which had high power of discrimination in Chinese.⑶The probability of15STR loci in agreement with Mendel,s law was high between twounrelated individual in autosomal STR database, only according to genetic evidence suchas CPI and RCP to determin paternity relationship can easily lead to fasle positiveresults.So, at least20autosomal STR loci should be detected in paternity testing,especially for duo paternity. X-STR or Y-STR chromosomal loci or other detectingtechniques should be added in special cases in order to ensure the accurate and scientificidentification results. |
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