Association study of MC1R gene polymorphisms with freckles in Chinese Han population from Chengdu / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the association between single nucleotide polymorphisms (SNPs) of melanocortin-1 receptor gene (MC1R) and freckles in Chinese Han population from Chengdu.</p><p><b>METHODS</b>Twenty randomly selected samples were used to select SNPs of the MC1R gene through DNA sequencing. Pyrosequencing in combination with DNA pooling technique was used to assess allelic frequencies of the selected SNPs in 111 individuals with freckles and 124 normal controls. Representative SNPs were selected based on their functional implications and minimum allele frequency (MAF> 0.05). Genotype of the SNPs were determined with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or pyrosequencing.</p><p><b>RESULTS</b>Based on results of DNA sequencing and pyrosequencing, 4 SNPs (rs2228479, rs885479, rs33932559 and rs2228478) were selected to determine the genotype for each sample. Comparison of genotypic and allelic frequencies of the 4 SNPs with χ (2) test has found no significant difference between the two groups (P> 0.05). For rs33932559, the frequencies of T allele were respectively 90.09% and 91.94% for individuals with freckles and normal controls. For rs2228479 and rs2228478, the frequencies of G and A allele were both about 77%. For rs885479, the frequency of T allele was about 60%. None of the above 3 SNPs showed a significant difference between the two groups in terms of allelic or genotypic frequencies.</p><p><b>CONCLUSION</b>No association between the selected SNPs of MC1R gene has been found with development of freckles for the selected Chinese Han population from Chengdu.</p>

Evaluation of Genetic Markers in a Novel Diagnostic Strategy for Trisomy Based on Short Tandem Repeats / 现代生物医学进展

Background:In the newly published article,we presented a novel STR-based diagnostic strategy for trisomy.When applying the strategy to the detection of the copy number of the selected chromosome,it is necessary at first to construct a multi-marker diagnostic system for trisomy by selecting the optimal chromosome-specific STR markers from numerous STR polymorphisms in human genome.Objective:Attempting to provide a reliable method for selecting optimal STR markers to construct a diagnositic system of high efficiency,in this study,we further described the quantitative evaluation of single STR marker and multimarker system during the marker selection.Methods:We deduced the formulae of three-allele detection rae(TDR)and the probability that three different alleles are observed in a diagnostic system.(P),by which we can quantitatively evaluate efficacy of a STR marker and cumulative efficacy of a multi-marker diagnostic system.Furthermore,we applied them to a multi-marker diagnostic system for trisomy 21 which was constructed in the previous study.Results:The TDR values of nine STR markers in our diagnostic system for trisomy 21 ranged from 0.203 to 0.638.The probability that three different alleles are observed in the system is above 0.95.Conclusion:The numerical values obtained from the formulae can provide a basis for the selection of optimal STR markers and the determination of the number of STR markers needed in a system with high efficacy.

Application of multiplex amplification of STRs for monitoring survival of engraftment after bone marrow transplantation / 临床检验杂志

Objective To evaluate the application of fluorescent multiplex amplification of short tandem repeat(STR)for monitoring survival of engraftment after bone marrow transplantation(BMT).Methods Three STR loci named D12S391,D18S865 and D20S161 in 56 cases were detected by fluorescent multiplex amplification.PCR products were separated and typed by DNA Sequencer.Results The genotypes of STR in 52 recipient after bone marrow transplantation were completely identical with those of the donors.In another 4 cases the evidences of mixed chimerism were observed.Conclusion The system of fluorescent multiplex amplification of STRs exhibited high capacity of discrimination and low cost.Its application in the detection of STR after BMT is reliable,sensitive and simple.Combined with the clinical manifestation it can be used to evaluate the effect of BMT.

Genetic polymorphisms of fifteen short tandem repeat loci in Chengdu Han population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To acquire the population genetic data of fifteen short tandem repeat (STR) loci in Chengdu Han population.</p><p><b>METHODS</b>A total of 210 EDTA-blood specimens were collected from the unrelated individuals in Chengdu Han population. The DNA samples were extracted with Chelex method and amplified by multiplex PCR technique. The PCR products were analyzed by an automatic genetic analyzer; the relative fragment's lengths of PCR products were calculated by gene scan analysis software and afterward genotyped by genotype software.</p><p><b>RESULTS</b>Fifteen STR loci of the 210 samples showed a successful result of genotyping. The heterozygosities of the fifteen STR loci in Chengdu Han population were found to be 0.529-0.881; the combined exclusion probability and discrimination power for the fifteen STR loci in Chengdu Han population were determined to be 0.999998 and 7.3 x 10 (-17); respectively.</p><p><b>CONCLUSION</b>The distinct genotype of fifteen STR loci and the sex of sample could be unveiled just through PCR and electrophoresis once, and a higher measured value could be obtained for both the combined discrimination power and the exclusion probability; the fifteen STR loci can meet the needs of the parentage testing and personal identification in forensic medicine.</p>

The relationship between physical distance and genetic distance on chromosome 22 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To construct a genetic map based on data from the Chinese population in northern part of China and to compare relationship between physical distance and genetic distance on chromosome 22.</p><p><b>METHODS</b>PCR amplification was employed to genotype 6 STR loci on chromosome 22, and pedigree analysis was performed.</p><p><b>RESULTS</b>A genetic map of Chinese Han population in the northern part of China was constructed and a preliminary comparison of the physical and genetic distances between 6 STR loci on chromosome 22 was made.</p><p><b>CONCLUSION</b>There is complex relationship between genetic distance and physical distance: the distance between STR loci is related to physical distance but also recombination fraction, and there are differences of the genetic and physical distances on chromosome 22 between Chinese and Caucasian, and between the male and female.</p>

A study of forensic DNA databases / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>The forensic DNA databases are very important for individual identification. In order to evaluate the genetic markers used for a forensic DNA databases and the compatibility between the manual DNA typing system and the automatic DNA typing system, a testing DNA database should be constructed. Also, constructing a testing DNA database can increase our understanding of the issue for forensic DNA databases.</p><p><b>METHODS</b>A total of 1000 specimens, including samples of blood, blood stains, salvia stains, semen stains, mixture stains and muscle tissues, were collected from the public security bureau of Chengdu. The DNA of each specimen was extracted by Chelex method and analyzed using Amp-FLP technique. A total of 8 STR loci, including D3S1358, D9S1118, vWA, D5S818, D16S539, D8S1179, CSF1PO and D20S161 were chosen and employed for DNA typing. Each STR locus was amplified by the polymerase chain reaction PCR and the PCR products were typed with the polyacryamide gel electrophoresis. Typing DNA was carried out by comparing with a human allele ladder. A total of 8 human allele ladders for D3S1358, D9S1118, vWA, D5S818, D16S539, D8S1179, CSF1PO and D20S161 were made in-house. Managing software of the testing DNA database was designed using Microsoft Access.</p><p><b>RESULTS</b>The results of DNA typing in 1000 specimens showed that the total discrimination power of 8 STR loci was over 0.99999999.</p><p><b>CONCLUSION</b>This study show that a forensic DNA database should be useful for search purpose. The total discrimination power over 0.99999999 imply that in principle there is no identical genotype at whole 8 STR loci between two persons from a population with 10000000 individuals. This means that 8 STR loci used in this study are suitable to construct forensic DNA databases in Chengdu of China. The result of DNA typing can be repeated and the data have compatibility between the manual DNA typing system and the automatic DNA typing system. The data search in our testing DNA database can be carried out using only some loci of the set of 8 STR markers. Also, the volume of our testing DNA databases could be enlarged easily. The implication from this study is that the legislation should not be negligent before establishing a forensic DNA database. This DNA database provides a model for establishing the forensic DNA databases in China.</p>

Genetic polymorphism and forensic application of five novel STR loci / 中国输血杂志

0.85,and the exclusion probabilities ≥0.48.The independence test of 5 loci proved that there were no correlations between the two STRs in 5 pairs,which were LFG26 and LFG21,LFG20 and LFG24,LFG21 and LFG24,LFG24 and LFG26,LFG24 and LFG29.Therefore they could be used simultaneously.Conclusion The forensic study of 5 STRs on chromosome 21 revealed that LFG21,LFG24,LFG26 and LFG29 were good candidates as polymorphic markers for forensic DNA analysis.

Y-STRs Multiplex Amplification and Validation for Forensic Scieuce / 中国法医学杂志

Objective In order to increase significantly the discriminatory potential of Y-STR systems available to the forensic community , We have developed and validated a four-color fluorescence multiplex PCR system consisting of 7 male-specific and polymorphic Y-STRs. Methods We designed three sets of constant primers chimerited into three groups of 7 Y-STR's specific primers and utilized fluorescence- labeled these three sets of constant primers to amplified simultaneously 7 Y-STRs in a reaction tube. Allele and haplotype frequencies at these Y-STRs were screened by ABI PRISM310 Genetic Analyzer and analyzed by Genotyper software. Results Following optimization of the polymerase chain reaction , DYS434, Y-GATA-A10,DYS531, DYS557 , DYS456 , DYS444 and DYS448 in a sample of 120 unrelated males , showed4, 5, 5, 8, 8, 6,7 alleles respectively. A total of 101 different haplotypes was identified,of which 89 (88. 11% ) were found in single individuals. The overall haplotypes diversity reached 0.9958. To the one case of mixture stains, our multiplex system drawn conforming conclusion comparing to the result of Y-STR genotypes in suspect's blood sample. Conclusion Our results show that the multiplex system of 7 Y-STR will be very powerful for establishing Y-STR database, the paternity testing and mixture stains identifying.

Forensic application of D20S161 and D8S384 loci / 中国法医学杂志

To evaluate the forensic validation of D20S161 and D8S384 loci.Two typing kits for D20S161 and D8S384 had been home made.The samples had been analyzed by using both kits,which including human blood,human semen,human saliva,animal blood,mixture of human blood and animal blood;human bloodstain,human semen stain,human saliva stain,animal bloodstain, mixture stain of human blood and animal blood; old bloodstains.The sequences of primers for both loci had been compared with 606364 sequences in data base in GeneBank,USA.There are positive results for human blood,human semen,human saliva,mixture of human blood and animal blood by using both kits for D20S161 and D8S384 loci.But animal bloods have not any PCR-productyet.Genotyping of human bloodstain,human semen stain,human saliva stain,mixture stain of human blood and animal blood by using both kits for D20S161 and D8S384 loci were correct.But animal bloodstains had not any PCR productyet.Also, all of fifty old bloodstains had positive results of typing for D20S161 and D8S384.No product was obtained by PCR technigue when primers for both D20S161 and D8S384 loci were tested against 606364 known sequences in the data base in GeneBank.The results demonstrated that both loci have species specificity.Both D20S161 and D8S384 loci are useful marker for forensic casework and paternity analysis.