Study On Genetic Polymorphism Of STR Loci In Han And Tujia Nationality From Chongqing

Short tandem repeat (STR) is an ideal genetic marker with highpolymorphisms and genetic stable heredity. The characteristics of its short,efficient and multiple amplification make STR typing superior to thetraditional genetic marker. Therefore, STR typing is not only suitable foranalyzing degradation and minute amount of DNA, but also an importantmethod in forensic medicine for individual identification and paternity test.Chromosome Y does not recombine with any other at meiosis except thaton pseudoautosomal region (PAR). Y-STR is paternal inheritance andhaploidy inherited. The property makes it unique and important in forensicmedicine. This study based on Han male gender 115, female gender 15, Tujiamale gender 120, female 15 unrelated individual blood samples. DNA wasextracted with Chelex method. Each DNA sample was amplified using PCRfor GATA-A7.2, GATA-C4 and DYS437 locus. The PCR products of threeY-STR loci were analyzed by denaturing vertical polyacrylaminde gelelectrophoresis with continuous buffer system, genotyping with silver stainmethod. There were no PCR products of three Y-STR loci for the femaleindividual, it indicated that the three loci were specifically for thechromosome Y and there were no their homologous sequences on thechromosome X. Use direct counting method to calculate allele andgenotype frequency, calculate gene diversity (GD)/haplotype diversity(HD), the power of discrimination (DP/DP′) and the power of exclusion(PE/PE′) of three loci and compare two nationalities allele distributionfeature。 The HD, DP′and PE′ for the three Y-STR loci was 0.9556 in Hanand 0.9532 in Tujia. It was suggested that GATA-A7.2, GATA-C4 andDYS437 loci are suitable for individual identification and paternity testing,and they provide new selectable STR markers for chromosome Y haplotypein forensic application. Compared with Han and Tujia nationality, we foundthe three loci genetic distributions were no significant different (P>0.05),two nationalities may be have same origin. We acquired the allele and genotype frequencies data of 15 STR loci(CSF1PO, D13S317, D16S539, D18S51, D19S433, D21S11, D2S1338,D3S1358, D5S818, D7S820, D8S1179, FGA, TH01, TPOX, vWA) byfluorescent dye labeling multiplex STR-PCR, capillary electrophoresis andDNA sequencer GeneScan, Genotyping. Among the Tujia population, weobserved 141 alleles and 386 genotypes in 15 STR loci with theirfrequencies of 0.0043 ～ 0.5348 and 0.0087 ～ 0.3130. The genotypedistributions meet Hardy-Weinberg equilibrium through x2 testing (P>0.05).Statistical result showed that the heterozygosity(H) were ranged from0.6348 to 0.8870. The power of discrimination(DP) were 0.7965 ～0.9642,combined DP>0.999,999,999,9. The probability of matching (Pm)were 0.0358 ～ 0.2035, combined Pm was 3.12×10-17. The power ofexclusion (PE) were 0.3347～0.7689, combined PE=0.999,997,688,3. Thepolymorphism information content (PIC) were 0.5764～0.8583,combinedPIC=0.999,999,999,6. The paternity index (PI) were 1.3690～4.4231.Compared with four Chinese nationalities i.e. Tujia, Miao, Han, Li, wefound the genetic distributions were different, but compared with Rwandapeople, Brazilian and Polish, there were significant differences betweenethnic groups. The Chongqing Tujia nationality 15 STR genetic datarequired from this research not only provide basic data for Tujia nationalitygenetic study, establish China STR genetic database,and break a new areain forensic individual identification and paternity testing.