Interpretation Of The Results Of Mixed Dna And Forensic Applications,

Objective:Through the preparation of different proportion of mixture's simulation mixes DNA,using the high peak or peak area of mixed DNA type,and then using certain parameters to establish standards based on high peaks or peak area in the combination of various loci phenotype,assessing reasonable combination phenotype,establishing"restrictive combination model"for mixed DNA analysis to the results of DNA typing, thus to recognized the origin of two components in no suspects of male/female mixed DNA.Then throughing the actual cases,to analysis the scopes of application in forensic medicine,providing scientific and reasonable explanation for solving the male/female application of forensic DNA typing results.Methods:Selecting 007 positive control standard of AB-YfilerTM Kit known as male DNA,and choosing 9947A positive control standard of AB-ldentifilerTM Kit known as female DNA.the density of two DNA is 0.1 ng/μl. Preparation of different proportion of mixture's simulation mixes DNA,Using the two parameters of mixed type heterozygous balanced and mixed ratio,throughing sex loci to estimate the proportion of male DNA in two male/female mixture DNA,and to establish in high peaks or peak area information based on the combination of various loci phenotype,assessing reasonable phenotypic,thus to recognized the origin of two components in no suspects of male/female mixed DNA.And using high peaks and peak area of information to analysis male component mixture of 95%,50%,5%of nine mixed samples. When the mixture ratio of minor components in mixture is too low,it's often to considered from three types of a lack allele,two lack alleles,low DNA of lack alleles,adopt corresponding quantitative calculation formula.Results:25 cases of constant mixed DNA analysis results show:3 cases tested a number of loci 15 (100%),5 cases for 14(93%),4 cases for 13(87%),6 cases for 12(80%),3 cases for 1 1(73%)and minimum detectable for 8(53%),In mixture ratio 95%of there samples mixed DNA,appeared in order 2,1 and 4 loss alleles,the rest of the mixture DNA were no allele lack;Six cases of mixed samples appeared wrong alleles victimised in which 3 cases were 30%mixture ratio samples and each sample of wrong numbers is within 2 10ci;25 mixture samples of LR is more than 14 orders of magnitude.19 cases of constant low mixed DNA analysis results show:1 case of mixed samples of low copy detected for 12 loci(80%),1 case for 1 1(73%),and 4 cases of minimum detectable for 3(20%);6 samples appeared lack allele,which in mixed ratio less than 20%or total template 100pg of low copy mixed DNA;1 8 cases of sample appear wrong alleles;The same mixed ratio of 3 replications samples value difference between LR in magnitude 6.From three aspects of tested loci,lacked alleles and wrong loci,choose between peak area and high peaks statistical information on the results of the analysis of mixed DNA has no obvious difference differences.17 cases of actual case mixed DNA test results show:12 cases of constant cases,4 cases of mixed DNA samples from loci for 15,2 cases for 14,1 cases for 13,the lowest inspection tested for 10 were 1;5 cases appeared lack allele,in which 4 cases were only 1 loci appeared lack;12 cases have no alleles victimised phenomenon.5 cases of low copy mixed DNA cases,the most detectable for 9 loci and minimum for;only 1 samples appeared lack allele,10 cases of sample appear wrong alleles.Conclusion:Combined with 44 cases of mixed DNA and simulation of 17 cases of the actual cases mixed DNA analysis and results,we can draw the restrictive applicable scope of the method is:a relative fluorescence intensity of 15 loci mixture DNA phenotype in the highest alleles bands is greater than 1000rfu and mixted ratio more than 30%of male/female two mixed DNA.Using the high peaks or peak area to analyze are the same.In low copies of mixed DNA analysis,due to the phenomena of wrong allele can't quantify,the analysis of the application is restricted.