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X-chromosomal short tandem repeats (ChrX STRs) loci are used for forensic practice in recent years. Considering the unique heredity characteristics of ChrX, recombination and linkage disequilibrium (LD) among ChrX STR loci vary between male and female and different populations as well. However, there is a lack of data for analysis of recombination and linkage disequilibrium on ChrX STR loci in the Chinese population. In this work, a total of 303 unrelated individuals (203 males and 100 females) in the Chinese Han population were analyzed with Mentype Argus X-8 PCR amplification kit (DXS10135-DXS8378, DXS7132-DXS10074, HPRTB-DXS10101, and DXS10134-DXS7423). The recombination and linkage disequilibrium of the eight ChrX STR loci were investigated with HapMap LD plots and software ARLEQUIN 3.1. Allele frequencies of the eight loci and further population forensic genetic parameters were obtained. Our results revealed hotspots for recombination, and there was no obvious evidence for LD among the eight loci in the Chinese population. Our work implied that single locus frequencies rather than haplotype frequencies should be applied for forensic practice in the Chinese population.

Objective: To obtain the data in polymorphism distribution of the five short tandem repeat (STR) loci: D18S979, D11S2014, D18S548, D1S1667 and GATA164F07 of Chinese Han population in Chengdu, and to evaluate their usefulness in the field of species specificity in forensic science., Methods: PCR, polyacrylamide gel electrophoresis (PAGE) and silver staining techniques were used to analyze the DNA samples from 100 unrelated individuals of Chinese Han ethnic group in Chengdu. Twelve different animals: monkey, pig, dog, bull, goat, chicken, duck, eel, mudfish, rabbit, guinea pig and mouse were selected as controls in this study for evaluating the species specificity of the five STR loci., Results: Six alleles and twelve genotypes were observed in D18S979. Five alleles and eleven genotypes were observed in D11S2014. Five alleles and thirteen genotypes were observed in D18S548. Seven alleles and nineteen genotypes were observed in D1S1667. Six alleles and fourteen genotypes were observed in GATA164F07. The genotype distributions of the five loci were analyzed by some related software and no deviation from the Hardy-Weinberg equilibrium was observed. Evaluated by way of using different animals as controls, monkey had amplification products at the extra-typing field of D18S979, D11S2014 and D1S1667. Bull, dog and eel had amplification product at typing field of D18S979, and pig, duck, mouse and rabbit had weak product. Bull had weak product at the typing field of D18S548. Dog, goat and eel had product at the typing field of D1S1667. Dog had weak product at the typing field of GATA164F07. Mudfish, chicken and guinea pig had no amplification product at the five loci., Conclusion: These data indicate that D18S979, D18S548, D1S1667 and GATA164F07 are highly polymorphic and D11S2014, D18S548 and GATA164F07 can play a key role in species identification.

Objective: In order to increase significantly the discriminatory potential of Y-STR systems available to the forensic community, we have developed a system capable of simultaneously amplifying 9 Y-STR loci by fluorescence-labeled multiplex PCR technique., Methods: Primers of STR loci DYS434, GATA-A10, DYS438 and DYS439 were labeled with 6-FAM, primers of STR loci DYS531, DYS557, DYS448 were labeled with HEX, and primers of STR loci DYS456, DYS444 were labeled with TAMRA, respectively. PCR products were analyzed using capillary electrophoresis and GeneScan Software on the ABI Prism310 DNA Analyzer. Series experiments were carried out to evaluate the useful value in forensic application such as the sensitivity, male specificity and genotyping DNA different tissues of the same individual., Results: 9 Y-STR loci were exactly determined following optimization of the polymerase chain reaction. In a sample of 120 males, a total of 105 different haplotypes was identified, 97 of them being unique. Overall, haplotype diversity was 0.996 8. It was proved that genotyping of these 9 Y-STR loci in some sexual crime should be prior to that of automosomal STR., Conclusion: The results suggest that the newly constructed 9-plex will be very powerful for establishing Y-STR database, population genetic studies and mixture stains identification.

Objective: To construct STR slippage model and study factors involved in this procedure., Methods: DNA samples were amplified with the technology of Degenerate oligonucleotide- primed PCR, then their products were taken as later DNA template and their STR genotype were analyzed by optimizing several factors., Results: STR slippage model was constructed., Conclusion: Several factors were involved in the produce of STR slippage, such as amount of modulate DNA, concentration of MgCl2, property of DNA polymerase, motif sequence of STR loci, sample, etc.

Objective: To build the four STR loci typing system by fluorescence labeled Multiplex-PCR technique, applied in the parentage test and personal identification in forensic medicine., Methods: The primer of D3S1754 and D1S549 were labeled with 6-FAM and TMR respectively, primers of D4S2366 and D12S375 were labeled with HEX. Multiplex-PCR products were analysed on the ABI PRISM 310 Genetic Analyzer where the Data Collection Software 3.0, the GeneScan Analysis Software 3.7NT and the Genotyper 3.7NT Software were used. This typing system has been emploied in the parentage test and personal identification of casework., Results: A method of typing four STR loci by fluorescence labeled Multiplex-PCR technique had been constructed. It has showed good sensitive and stability, and met the needs of parentage test and personal identification in forensic medicine., Conclusion: The constructed method can be used in studying genetic polymorphisms and parentage test or personal identification in forensic medicine.

To understanding the allele structure and genetic polymorphisms at five STR loci in Chinese Han population, and construct a preliminary database, EDTA-blood specimens were collected from unrelated individuals. DNA samples were extracted with Chelex method and were amplified by PCR technique. The PCR products were analyzed using both PAGE horizontal electrophoresis with discontinuous buffer system and automated fluorescence detection approach. As a result, three STRs consist of simple repeat motifs, while two STR contain a complex repeat structure. The STR polymorphisms at all of the five loci have been observed in Chinese Han population. In a word, the obtained data are beneficial to understanding the population genetics of the five STR loci in Chinese Han population. As a simple approach, the PAGE horizontal electrophoresis can be employed for typing the five STR markers.

Objective: We focus on developing a multiplex PCR system for Y-STR loci that can be detected by double fluorescent system and assessing their usefulness in forensic mixture samples., Methods: The primers of four Y-STR loci (DYS-GATA-A10, DYS531, DYS557 and DYS448) amplified by multiplex PCR technique were labeled with fluorescence, then the PCR products of these Y-STRs loci were detecting and typing by ABI PRISM310 Genetic Analyzer., Results: When 120 unrelated individuals from the Han population in Chengdu were detected by the system, Y-GATA-A10, DYS531, DYS557 and DYS448 showed 5, 5, 8, 7 alleles, respectively. A total of 78 different haplotypes was identified and the genetic diversity reached 0.9881. To the three cases of mixture stains failed by using conventional autosomal STR analysis, our multiplex system drew conforming conclusion comparing to the suspect's Y-STRs genotypes., Conclusion: Our results show that the multiplex system of four Y-STR will be very powerful for Y-STR database establishing, the paternity testing and mixture stains identifying.

Objective: To develop a set of new markers for forensic application, the authors have chosen 6 short tandem repeat(STR) loci to study the allele frequencies and species specificity in Chinese Han population in Chengdu., Methods: One hundred and ten EDTA-blood samples were collected from the unrelated individuals in Chengdu city, Sichuan province. DNA was extracted by Chelex-100 and amplified by the polymerase chain reaction(PCR). Polyacrylamide gel electrophoresis (PAGE) and silver staining were used to analyze the PCR products., Results: The polymorphisms of all 6 STR loci have been obtained in Chinese Han population in Chengdu, the alleles of D4S2366, D4S2367, D6S474, D6S1281, D2S1396 and D20S601 being 7, 7, 6, 7, 5, 7, the observed heterozygosity of them being 0.802, 0.708, 0.770, 0.627, 0.542, 0.672, the discrimination power of them being 0.887, 0.828, 0.849, 0.848, 0.794, 0.865; and the power of exclusion of them being 0.602, 0.441, 0.544, 0.325, 0.227, 0.386. Evaluated by comparison with the data from 14 different animals as controls, the 6 STR loci contain good specificity of human beings., Conclusion: The 6 STR loci are highly polymorphic and can play a key role in species identification. They are new candidate markers for forensic personal identification and paternity testing.

Objective: To obtain the data of polymorphism distribution of the two STR loci D2S2944, D1S2134 in Chinese Han population in Chengdu and evaluate their usefulness in the field of forensic science., Methods: PCR, polyacrylamide gel electrophoresis (PAGE) and silver staining were used to analyze 120 unrelated individuals of Chinese Han ethnic group in Chengdu. Fourteen different animals: monkey, pig, dog, bull, goat, chicken, duck, fish, cat, rabbit, Guinea pig, mouse, eel and frog were selected as controls in this study for evaluating the species specificity of the two STR loci., Results: Eight alleles and twenty-two genotypes were found in D2S2944. The observed heterozygosity (h), discrimination power (DP), polymorphism information content (PIC), chance of paternity exclusion power (EP) were 0.824, 0.925, 0.78, 0.644 respectively. Ten alleles and twenty-six genotypes were observed in D1S2134. The h, DP, PIC and EP were 0.769, 0.920, 0.79, 0.543 respectively. The genotype distributions of the two loci were analyzed by some related software and no deviation from the Hardy-Weinberg equilibrium was observed. Evaluated by way of using different animals as controls, the two STR loci of human beings were found to have good specificity., Conclusion: These data indicate that D1S2134 and D2S2944 are of good polymorphism, high EP and DP, and can be applied as the candidate genetic marks to forensic parentage testing and identification. The methods to analyze them are simple, dependable and repeatable.

Objective: To understand the allele structure and genetic polymorphism at three STR loci on chromosome X in Chinese Han population and make an evalution of their forensic application., Methods: EDTA-blood samples were collected from the unrelated individuals in Chengdu, China. After being extracted with Chelex method, the DNA samples were amplified by PCR technique. The PCR products were analyzed by PAG electrophoresis and the approach of automated fluorescence detection. Hardy-Weinberg equilibrium of females was tested and every forensic interested value was calculated., Results: The polymorphisms of all 3 STR loci were obtained from 100 unrelated females and 120 unrelated males from Chinese Han ethnic group. Chi-square tests on the genotype frequencies in females did not reveal deviations from Hardy-Weinberg equilibrium., Conclusion: The obtained data are beneficial to understanding the population genetics of the three STR loci in Chinese Han population. For forensic genetics, the obtained data can be used to calculate the probabilities dealing with the paternity test and the individual identification.

In this study we analyzed the eight Y-STR loci, DYS443, DYS444, DYS448, DYS453, DYS455, DYS456, DYS457 (DYS437) and DYS458, investigated haplotype distributions of these Y-STR loci in a Chinese Han population, and sequenced alleles of the eight loci for clarifying the structure. Extracted DNA was amplified by PCR and the PCR products were analyzed by non-denaturing horizontal polyacrylamide gel electrophoresis with a discontinuous buffer system. Alleles were sequenced on an ABI 3700 using a Dye Terminator Cycle sequencing kit. DYS443, DYS453, DYS455 and DYS456 were found to be simple repeat systems, while DYS444, DYS448, DYS457 (DYS437) and DYS458 were complex repeat systems. The gene diversities of DYS443, DYS444, DYS448, DYS453, DYS455, DYS456, DYS457 (DYS437) and DYS458 were 0.7742, 0.7671, 0.7453, 0.3545, 0.0549, 0.6988, 0.6148 and 0.8213, respectively. The haplotype diversity for 8 Y-STR loci was 0.9996, and the discrimination capacity was 0.9815. The results indicate that these eight loci are useful Y-linked markers for forensic applications.

To understand the genetic polymorphism of 10 STR loci on chromosome 9 and reveal the difference on the linkage maps of different populations, the author used a set of nine tetranucleotide- and one tritranucleotide-repeat STR markers on chromosome 9 chosen from Genome Data Bank. EDTA-blood was collected from unrelated family in Baiyin City, Gansu province. DNA was extracted by Chelex-100 method and amplified by the polymerase chain reaction (PCR). The PCR products were analyzed using PAGE electrophoresis. We calculated the allele frequencies and heterozygosity and PIC of every ten STR loci. Using the data of Chinese Han pedigree, we constructed a genetic map of chromosome 9 making up with 10 STR loci. Then we compared our map with the map in GDB. Our results indicate that there are some differences on the genetic map between Chinese and GDB. That means, it is essential to do some population genetic evaluations before using the data of GDB into Chinese population.