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Search Results: 1 - 10 of 2868 matches for " Short tandem repeats "
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Utilizing Short Tandem Repeats (STRs) as a Resolving Matrix in Parental Dispute DNA Analysis  [PDF]
George Gborienemi Simeon, Alade Tolulope Olukemi
American Journal of Molecular Biology (AJMB) , 2018, DOI: 10.4236/ajmb.2018.83013
Abstract: Interest in DNA analysis using short tandem repeats (STR) as finger printing tools in forensic medicine has gained tremendous application, as expression of these nuclear factors have enhanced forensic examination. Here we used this Biochemical characterization after conventional extraction process, polymerase chain reaction (PCR), gel electrophoresiss and a sequencer to distinguish and resolve parental dispute. The differential migration of labeled DNA fragments which attains excitation energy with a laser elicits fluorescent light of different wavelength depending on the dye used. A data collection software (Genemapper) collects raw data (spectrograph) and converts it to an electropherogram that is interpreted. By comparing the DNA profiles, inclusion and exclusion criteria were elucidated to resolve disputes. The inherent discriminating power of STRs used in analysis enhances resolution of cell mixtures, genetic aberration, substantiation of tissue origin and provides genetic distinction which is a robust and reliable approach in resolving parental disputes.
Efficacy of DNA typing as an accurate method in forensic medicine
Tofighi H,Hassanian Moghaddam H,Naji M,Nikbakht Dehkordi A
Tehran University Medical Journal , 2000,
Abstract: DNA typing is a new method with important applications in forensic medicine. In the present study, we evaluated application of DNA typing in Iran. Loci Hum LPL, Hum Tpox, Hum F13, Hum vw 31A, Hum TH01 and Hum FES/FPS of DNA short tandem repeats were studied. To determine sensitivity of the test, 85 mother-child couples (1020 chromosomes) that were referred to DNA section of legal medicine organization of Iran were included and for determination of it's specificity 42 brother-sister couples (1200 chromosomes) and 58 non-relative couples were examined. The results show lack of mutations in the studied loci and acceptable sensitivity of the test. Of 12 alleles of siblings, there were 2-6 differences, in contrast with 3-9 differences in non-relatives, so the test has 100% specificity in these loci. Considering polymorphism, power of exclusion of these 6 sites was 99%.
Application of DNA Typing Technologies in Forensic Medicine
Batool Mutar Mahdi
Arsiv Kaynak Tarama Dergisi , 2013,
Abstract: Nuclear DNA markers are widely used for crime investigation and paternity testing. Parentage testing interpretation relies on the fact that Short Tandem Repeats are inherited in a true Mendelian fashion and express a codominant nature of allelic variants. DNA microsatellites or Short Tandem Repeats are short, tandemly repeated sequences of a bi-, tri- or tetranucleotide unit with a random distribution throughout the genome. They have been used extensively in applications as diverse as diagnosis of inherited diseases and forensic medicine for DNA fingerprinting and parentage testing. The success of this last application is due to the fact that Short Tandem Repeats are highly polymorphic and, at the same time, they are sufficiently stable to be inherited unaltered from one generation to the next. [Archives Medical Review Journal 2013; 22(3.000): 335-346]
Species Specificity Using Fifteen PCR-based Human STR Systems
Adnan Jaran,Salem Yasin
Journal of Biological Sciences , 2006,
Abstract: Contamination of biological evidence with non-human DNA complicates forensic analysis and necessitates the use of sets of primers that show high specificity for human DNA. We report here the analysis of DNA from 15 vertebrate animals in addition to that of humans (males and females) using the PowerPlex 16 system to assess its specificity for human euchromatin. The loci tested include, Penta E, D18S51, D21S11, TH01, D3S1358, FGA, TPOX, D8S1179, vWA, Penta D, CSF1PO, D16S539, D7S820, D13S317 and D5S818. There were no STR PCR products observed for the 15 species regardless of the STR system. Amelogenin-PCR fragments were all below 100 bp and consist of only one fragment irrespective of the sex.
Investigation of QF-PCR Application for Rapid Prenatal Diagnosis of Chromosomal Aneuploidies in Iranian Population
Habib Nasiri,Mohammad-Reza Noori-Dalooi,Jila Dastan,Saeed-Reza Ghaffari
Iranian Journal of Pediatrics , 2011,
Abstract: Objective:G-Banding followed by standard chromosome analysis is routinely used for prenatal detection of chromosomal abnormalities. In recent years, molecular cytogenetic techniques have been developed for rapid diagnosis of chromosomal abnormalities. Among these methods Quantitative Florescence Polymerase Chain Reaction (QF-PCR) has been widely used for this purpose. HHeterozygosity of short tandem repeat (STR) markers which leads to informativity is the most critical requirement for feasibility of QF-PCR. Methods:In this study we analyzed several short tandem repeats on chromosomes 13, 18, 21, X and Y on amniotic fluid samples obtained from PND candidates to diagnose conditions such as Down, Edward and Patau syndromes and also numerical sex chromosome abnormalities such as Klinefelter and Turner syndromes. Findings:Most of the analyzed STRs had acceptable heterozygosity (66.3-94.7) to be used in QF-PCR based prenatal diagnosis. Moreover, results obtained from both methods (standard karyotype and QF-PCR) for all samples were in accordance with each other. Conclusion:In case of using appropriate STR markers, and in certain clinical indications, QF-PCR could be used as useful technique for prenatal diagnosis even in consanguine populations such as Iranians.
DNA quantification by real time PCR and short tandem repeats (STRs) amplification results
Zoppis S,D’Alessio A,Rosini M,Vecchiotti C
Prevention and Research : International Open Access Journal of Prevention and Research in Medicine , 2012, DOI: 10.7362/2240-2594.082.2012
Abstract: Determining the DNA amount in a forensic sample is fundamental for PCR-based analyses because if on one hand an excessive amount of template may cause the appearance of additional or out-of-scale peaks, by the other a low quantity can determine the appearance of stochastic phenomena affecting the PCR reaction and the subsequent interpretation of typing results. In the common practice of forensic genetics laboratories, the quantification results provided by Real Time PCR (qPCR) assume the role of “boundary line” between the possibility for a given DNA sample to be subjected or not to the subsequent analytical steps, on the basis of an optimal amount of DNA in the range indicated by the manufacturer of the specific commercial kit.However, some studies have shown the possibility to obtain STR typing results even with an extremely low DNA concentration or, paradoxically, equal to zero (1). Regardless of the amount of DNA used for the quantification of the testing sample, specific software are able to use the standard curve to calculate concentration values far below the manufacturer’s reported optimal detection limit (0.023 ng/μL). Consequently, laboratories have to face the critical decision to interrupt the analyses giving up the possibility to obtain a genetic profile -although partial- or to try the amplification of the extract with the awareness of the interpretation issues that this implies.The authors will present the quantification results obtained by qPCR performed on numerous samples collected from items of forensic interest, subjected to DNA extraction using magnetic beads. Following the quantification step, the extracts were subjected to DNA amplification and STR typing using last generation commercial kits. Samples that showed quantification values below the limit of detection for the method were included in the analysis in order to check the existence of a correlation between the DNA quantification results by qPCR and the possibility of obtaining a genetic profile useful for identification purposes.Our study, performed on 558 samples from forensic casework items, has shown a correlation between the DNA amount resulted from qPCR analysis and the possibility of obtaining a genetic profile useful for identification purposes.In spite of the increasing sensitivity of last generation commercial kits for STR analysis, as demonstrated by the ability to detect allelic peaks from extremely low DNA quantities (with concentrations far below the limit of detection for the specific quantification kit, even corresponding to 0 or “Undetermined”), the results
Detecting Microsatellites in Genome Data: Variance in Definitions and Bioinformatic Approaches Cause Systematic Bias
Angelika Merkel,Neil J. Gemmell
Evolutionary Bioinformatics , 2008,
Abstract: Microsatellites are currently one of the most commonly used genetic markers. The application of bioinformatic tools has become common practice in the study of these short tandem repeats (STR). However, in silico studies can suffer from study bias. Using a meta-analysis on microsatellite distribution in yeast we show that estimates of numbers of repeats reported by different studies can differ in the order of several magnitudes, even within a single genome. These differences arise because varying definitions of microsatellites, spanning repeat size, array length and array composition, are used in different search paradigms, with minimum array length being the main influencing factor. Structural differences in the implemented search algorithm additionally contribute to variation in the number of repeats detected. We suggest that for future studies a consistent approach to STR searches is adopted in order to improve the power of intra- and interspecific comparisons
Reconstructing recent human phylogenies with forensic STR loci: A statistical approach
Suraksha Agrawal, Faisal Khan
BMC Genetics , 2005, DOI: 10.1186/1471-2156-6-47
Abstract: Phylogenetic analysis based on two different approaches – genetic distance and maximum likelihood along with statistical bootstrapping procedure involving 1000 replicates was carried out. The ensuing tree topologies and PC plots were further compared with those obtained in earlier phylogenetic investigations. The compiled database of 21 populations got segregated and finely resolved into three basal clusters with very high bootstrap values corresponding to three geo-ethnic groups of African, Orientals, and Caucasians.Based on this study we conclude that if appropriate and logistic statistical approaches are followed then even lesser number of forensic STR loci are powerful enough to reconstruct the recent human phylogenies despite of their relatively high mutation rates.Short Tandem Repeats (STR), with a repetitive sequence ranging from 2–6 base pairs are amongst the most polymorphic markers reported till date. They exhibit substantial allelic variability due to high rate of germline mutations [1]. The STR loci have a uniform and dense distribution throughout the genome and exhibit high level of relatively stable polymorphism [2]. All these features makes them an ideal candidate for diverse applications including forensic applications [3], individual identification, paternity/maternity detection [2], fine scale genetic mapping [4] and inter and intra group phylogenetic reconstruction [5].However, a specific set of STR can be employed for specific applications and this specificity is solely based on the properties of STR loci involved and their suitability to the particular application. STR loci used for forensic purposes are the one that possess numerous observed alleles, high level of heterozygosity, high polymorphism information content and high power of exclusion. On the contrary, STR loci preferred for the phylogenetic analysis of the human populations are those which have substantial lower allelic counts and carries signature alleles for specific populations [6
Inference of ancestry: constructing hierarchical reference populations and assigning unknown individuals
Jayne E Ekins, Jacob B Ekins, Lara Layton, Luke AD Hutchison, Natalie M Myres, Scott R Woodward
Human Genomics , 2006, DOI: 10.1186/1479-7364-2-4-212
Impact of human population history on distributions of individual-level genetic distance
Joanna L Mountain, Uma Ramakrishnan
Human Genomics , 2005, DOI: 10.1186/1479-7364-2-1-4
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