TWGDAM validation of AmpFlSTR PCR amplification kits for forensic DNA casework

Laboratory procedures used in short tandem repeat (STR) analysis were subjected to various scenarios that assessed reliability and identified potential limitations. These validation studies were designed as recommended by the Technical Working Group on DNA Analysis Methods (TWGDAM) and the DNA Advisory Board (DAB) (17,18). Various DNA samples were amplified by the polymerase chain reaction (PCR) using AmpFlSTR PCR Amplification Kits (i.e., AmpFlSTR Green I, Profiler, Profiler Plus, and COfiler kits), detected with ABI Prism instrumentation, and analyzed using GeneScan and Genotyper software. Data acquired in these studies reinforced an existing body of knowledge and expertise regarding application and interpretation of STR typing in the forensic science community. Consistent STR genotypes were detected in various body tissues and fluids. Inter-laboratory comparisons produced concordant genotype results. Quantitative interpretational aids for DNA mixtures were characterized. Ability of the typing systems to type potentially compromised samples reliably was evaluated. Nonprobative case evidentiary DNA was successfully amplified, genotyped, and interpreted. Potential limitations or cautionary factors in the interpretation of minimal fluorescence intensity were demonstrated. Differential amplification between loci was observed when PCR was inhibited; preferential amplification typically was not. Single AmpFlSTR locus amplification did not offer consistent benefit over AmpFlSTR multiplexing, even in cases of DNA degradation or PCR inhibition. During rigorous evaluation, AmpFlSTR PCR Amplification Kits reproducibly yielded sensitive and locus-specific results, as required in routine forensic analyses.     

Concordance study on population database samples using the PowerPlex 16 kit and AmpFlSTR Profiler Plus kit and AmpFlSTR COfiler kit

Over 500 population database samples comprising African Americans, Bahamians, and Southwestern Hispanics were typed using the PowerPlex 16 and the Profiler Plus COfiler kits. There was only one sample in which a typing difference was observed. An FGA heterozygote profile was observed using the PowerPlex 16 primers, and a single allele FGA profile was observed using Profiler Plus primers. Thus, the extant data suggest that the primers used in the PowerPlex 16, Profiler Plus, and COfiler kits are reliable for typing reference samples destined for use in CODIS. In addition, African American, Bahamian, and Southwestern Hispanic databases have been established for the STR loci Penta D and Penta E. Both loci are highly polymorphic. The application of the product rule is valid for estimating the rarity of a multiple loci profile consisting of these two and the 13 core STR loci.     

Performance evaluation of two multiplexes used in fluorescent short tandem repeat DNA analysis

The performance of two commercial multiplex kits that together amplify the 13 core short tandem repeat (STR) loci currently in use by forensic laboratories and the U.S. national Combined DNA Indexing System (CODIS) were evaluated. The typing systems examined were AmpFlSTR Profiler Plus and AmpFlSTR COfiler (PE Applied Biosystems, Foster City, CA). Electrophoretic separation and detection of the fluorescent PCR products was achieved by capillary electrophoresis (CE) using an ABI Prism 310 Genetic Analyzer. The studies addressed the on-site validation of the instrument, the software, and each typing system. These studies included instrument sensitivity, resolution, precision, binning, peak height ratios, mixtures, stutter, and the amplification of non-probative and simulated forensic samples. Other additional developmental-type work is also reported herein, such as species specificity testing and amplification of environmentally insulted samples. Amplification conditions were found to be robust and the primer sets shown to be specific to human DNA. Stutter and peak height ratios fell within limits published by the manufacturer and other laboratories. The data demonstrate that the CE instrument can consistently resolve fragments differing in length by one base and that the +/-0.5 base bin used by the Genotyper software is acceptable for making accurate allele calls. Correct typing results were obtained from non-probative and simulated case samples, as well as samples exposed to outdoor environmental conditions. The results support the conclusion that DNA extracted from biological samples routinely encountered in the forensic laboratory can be reliably analyzed with AmpFlSTR Profiler Plus and COfiler using CE.     

Validation of the AmpFlSTR Profiler Plus PCR amplification kit for use in forensic casework

According to TWGDAM guideline 4.5 (1), prior to implementing a new DNA analysis procedure or an existing DNA analysis procedure developed by another laboratory, the forensic laboratory must first demonstrate reliability of the procedure in-house. Seven phases were designed to validate the use of the AmpFlSTR Profiler Plus PCR Amplification Kit, as well as the PE Applied Biosystems 310 Genetic Analyzer. This report summarizes the results obtained for each of the seven phases of the validation study which included the following evaluations: polymer, reproducibility, sensitivity, stutter, precision, mixtures and nonprobative casework.     

AmpFlSTR Profiler Plus and AmpFlSTR COfiler analysis of tissues stored in GenoFix, a new tissue preservation solution for mass disaster DNA identification

A preliminary study was conducted to assess the capability of a new alcohol-based tissue fixative, GenoFix, to preserve DNA from biopsy tissues stored at room temperature and/or -20 degrees C in a freezer, for subsequent short tandem repeat (STR) DNA typing analysis. Fresh human smooth muscle samples were stored at room temperature in GenoFix for one month and up to one year and seven months before being processed using the megaplex STR systems, AmpFlSTR Profiler Plus and AmpFlSTR COfiler. Alternatively, muscle tissues in GenoFix were placed at -20 degrees C in a freezer for up to 3 1/2 years following two to three months in the fixative at room temperature. DNA analysis was also carried out on tissues stored in GenoFix for one month at room temperature and subsequently paraffin-embedded and stored at room temperature for four years. The AmpFlSTR Profiler Plus and AmpFlSTR COfiler STR profiles produced, using DNA extracted from all fixed tissue samples, were of very good quality. The fluorescent signals were well balanced across the nine STR loci or six loci comprised in the megaplexes surveyed and profiles showed no differences with those observed for the control blood of the respective donor patients. Continuous exposure to GenoFix at room temperature (up to one year and seven months) did not compromise the STR typing analysis of the fixed tissues. No adverse effects were noted on the STR typeability of tissues fixed with GenoFix and stored at -20 degrees C in a freezer for up to 3 1/2 years. STR profiles generated from the paraffin-embedded tissues fixed in GenoFix were of excellent quality. This preliminary study suggests that GenoFix can be used to store tissue samples at room temperature for up to one year and seven months or at -20 degrees C in a freezer for longer storage (up to 3 1/2 years). This new and odorless tissue fixative promotes tissue and DNA preservation in a very effective manner and as such may prove useful in criminal investigations or mass disaster identifications carried out in remote locations and in which a small or large number of tissue samples are collected for further analyses.     

AmpFlSTR profiler Plus short tandem repeat DNA analysis of casework samples, mixture samples, and nonhuman DNA samples amplified under reduced PCR volume conditions (25 microL)

As part of the validation of the AmpFlSTR Profiler Plus short tandem repeat (STR) system, under reduced polymerase chain reaction (PCR) volume conditions (i.e., 25 microL), a total of 275 casework samples were processed. Examples of profiles are presented along with amplification conditions to improve the odds of obtaining balanced and complete profiles for samples showing partial results or profiles with a descending slope. Data collected and used to develop our interpretation guidelines are included. From the mixture studies, full profiles were obtained for minor contributors, using 2 ng of DNA, with ratios of 10:1 or 1:20 and using 1 ng of DNA, with ratios of 10:1 and 1:8. The specificity of the Profiler Plus amplification reaction performed in 25 microL was examined and confirmed using a large spectrum of nonhuman DNAs. This report supports the use of the AmpFlSTR Profiler Plus STR system for casework DNA typing under reduced PCR volume conditions.     

STR primer concordance study.

Over 1500 population database samples comprising African Americans, Caucasians, Hispanics, Native Americans, Chamorros and Filipinos were typed using the PowerPlex 16 and the Profiler Plus/COfiler kits. Except for the D8S1179 locus in Chamorros and Filipinos from Guam, there were eight examples in which a typing difference due to allele dropout was observed. At the D8S1179 locus in the population samples from Guam, there were 13 examples of allele dropout observed when using the Profiler Plus kit. The data support that the primers used in the PowerPlex 16, Profiler Plus, and COfiler kits are reliable for typing reference samples that are for use in CODIS. In addition, allele frequency databases have been established for the STR loci Penta D and Penta E. Both loci are highly polymorphic.     

Profiler Plus试剂盒扩增Amelogenin基因座变异1例

目的探讨日常检案及DNA数据库建设中常用的ProfilerPlus系统扩增法医生物检材可能出现的变异情况。方法分别采用ProfilerPlus试剂盒扩增、毛细管电泳分析及Amelogenin单基因座扩增、银染技术分型两种方法分别检测两份血痕的基因型。结果应用ProfilerPlus试剂盒扩增、毛细管电泳分析发现X-Y同源Amelogenin基因座的X片段丢失,而运用Amelogenin单基因座扩增、银染技术分型则X片段正常出现。结论应用ProfilerPlus系统分析法医生物检材,有可能出现等位基因丢失现象,此现象需要引起我们在日常检案及DNA数据库建设中的足够重视。     

Belgian population data for 15 STR loci (AmpFlSTR SGM Plus and AmpFlSTR profiler PCR amplification kit)

The allele and genotype distributions for 15 STR loci included in the AmpFlSTR SGM Plus and AmpFlSTR Profiler kits (Applied Biosystems, Foster City, USA) were determined in a sample of 222 unrelated individuals of Belgian origin.     

STR data for the AmpFlSTR Profiler Plus and COfiler loci from the Maghreb (North Africa)

Allele frequencies for 13 STRs (D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, THO1, TPOX, CSF1PO and D16S539) included in the AmpFlSTR Profiler Plus and COfiler kits were determined for a population sample from the Maghreb (Northern Africa).     

Fast Multiplexed Polymerase Chain Reaction for Conventional and Microfluidic Short Tandem Repeat Analysis

Abstract:  The time required for short tandem repeat (STR) amplification is determined by the temperature ramp rates of the thermal cycler, the components of the reaction mix, and the properties of the reaction vessel. Multiplex amplifications in microfluidic biochip-based and conventional tube-based thermal cyclers have been demonstrated in 17.3 and 19 min, respectively. Optimized 28-cycle amplification protocols generated alleles with signal strengths above calling thresholds, heterozygous peak height ratios of greater than 0.65, and incomplete nontemplate nucleotide addition and stutter of less than 15%. Full CODIS-compatible profiles were generated using the Profiler Plus ID, COfiler and Identifiler primer sets. PCR performance over a wide range of DNA template levels from 0.006 to 4 ng was characterized by separation and detection on a microfluidic electrophoresis system, Genebench-FX^™. The fast multiplex PCR approach has the potential to reduce process time and cost for STR analysis and enables development of a fully integrated microfluidic forensic DNA analysis system.     

广东广西地区5个群体9个STR基因座的频率调查

目的 调查广东汉族、广西汉族、广西侗族、广西壮族、广西苗族5个群体9个STR基因座多态性,探讨其在法医学检验中的应用价值。方法 应用AmpFISTR Profiler PlusTM荧光标记复合扩增系统,对广东广西5个群体4个民族的1191个无关个体的血样DNA进行9个STR基因座的复合扩增;用ABI 3100遗传分析仪对扩增产物进行分型,统计9个STR基因座的群体遗传学参数。结果 9个STR基因座在广东广西地区5个群体中的累积偶合率为1.51×10-11～8.08×10-11,累积非父排除率为0.99981—0.99990。,结论 该9个STR基因座可满足汉族、壮族、侗族、苗族群体法医学的个体识别及亲权鉴定的需要。     

Swiss Caucasian population data for the STR loci D2S1338 and D19S433 using the AmpFISTR SGM plus PCR amplification kit

Allele and genotype frequencies for the ten STR loci D3S1358, VWA, D16S539, D2S1338, D8S1179, D21S11, D18S51, D19S433, TH01, FGA were determined in a Swiss Caucasian population sample (n=206) using the AmpFISTR SGM Plus Amplification kit. Electrophoresis was carried out on an ABI PRISM CE 310 Genetic Analyzer instrument. Previously, allele frequencies were published for the 13 STR loci D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, THO1, TPOX, CSF1PO and D16S539 for the same samples (n=206) amplified with the AmpFISTR Profiler Plus and Cofiler PCR Amplification kits. Since the results for the eight loci D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, THO1, D16S539 shared between the AmpFISTR SGM Plus, Profiler Plus and Cofiler PCR Amplification kits already are published, only the allele frequencies for the two STR loci D2S1338 and D19S433 are reported in this paper. The two loci meet Hardy-Weinberg expectations. In addition, there is little evidence for association of alleles among the 15 loci (amplified with the Profiler, Cofiler, and SGM Plus amplification kits). The allelic frequency data can be used in forensic analyses to estimate the frequency of a multiple STR locus DNA profile in the Swiss population.     

Identifiler体系在单亲血缘关系鉴定中应用价值的研究

目的　研究 16基因位点Identifiler体系在单亲血缘关系法医鉴定中的应用价值。　方法　对无关个体中随机抽样组成的假设父—子二联体 10 0例、正常人群中已知真父—子二联体 10 0例及已知非父—子二联体 10 0例、实际单亲血缘关系亲子鉴定案 2 2 8例、特意省去母亲的二联体鉴定案 136例 ,应用Identifiler体系的 16基因位点进行检测 ,得出每案例的RCP值 ,将检测结果同应用其他体系检测的结果比对 ,同三联体检测结果比对 ,同真实情况比对 ,计算出单独使用Identifiler体系在单亲血缘关系法医鉴定中的正确率。　结果　对 2 2 8例单亲鉴定案应用Identifiler体系检测的结果 ,同应用ProfilerPlus和Cofiler两个体系再加用 2 4个其他位点银染检测 (共 37个位点 )的结果完全相同 ;对无关个体 10 0例及真父—子二联体 10 0例及非父—子二联体 10 0例 ,用Identifiler体系检测的结果同调查核实的真实情况完全相符 ;对 136例特意省去母亲的二联体案 ,用Identifiler体系检测的结果同原实际检案中三联体检测的结果完全相同。　结论　单独使用Identifiler体系完全可以解决法医亲子鉴定中的单亲血缘关系鉴定问题。     

Validation and casework application of a Y chromosome specific STR multiplex

A series of validation experiments was performed for a Y chromosome specific STR multiplex system following the suggestions made by the Technical Working Group DNA Analysis Methods (TWGDAM). The multiplex PCR products were detected on Perkin-Elmer 373 and 377 automated sequencers using two labeling colors. No problems regarding the stability, robustness and sensitivity of the Y STR multiplex were observed. Mixture studies revealed a cut off rate similar to autosomal STRs for mixtures of male DNAs and no interference of any female admixture. The comparison of the Y STR results to the autosomal typing results for 56 nonprobative semen stains and swabs, showed a slightly higher success rate in detecting the semen donor's alleles for the Y STR multiplex. Two examples are shown to illustrate the usefulness of Y STR typing for DNA mixtures. In one case the Y STR results confirmed an isolated exclusion; in the other case, the interpretation of a mixture was clarified since the Y STR results proved the presence of DNA from at least two semen donors. Y STR typing is a valuable addition to the forensic DNA testing panel.     

Rapid and high-throughput forensic short tandem repeat typing using a 96-lane microfabricated capillary array electrophoresis microdevice

A 96-channel microfabricated capillary array electrophoresis (muCAE) device was evaluated for forensic short tandem repeat (STR) typing using PowerPlex 16 and AmpFlSTR Profiler Plus multiplex PCR systems. The high-throughput muCAE system produced high-speed <30-min parallel sample separations with single-base resolution. Forty-eight previously analyzed single-source samples were accurately typed, as confirmed on an ABI Prism 310 and/or the Hitachi FMBIO II. Minor alleles in 3:1 mixture samples containing female and male DNA were reliably typed as well. The instrument produced full profiles from sample DNA down to 0.17 ng, a threshold similar to that found for the ABI 310. Seventeen nonprobative samples from various evidentiary biological stains were also correctly typed. The successful application of the muCAE device to actual forensic STR typing samples is a significant step toward the development of a completely integrated STR analysis microdevice.     

Analysis of human fecal material for autosomal and Y chromosome STRs

Human stool samples from eight volunteers were stored under various conditions and extracted by three different procedures. Fecal material and tissue paper soiled with fecal material obtained from a crime scene were also extracted. Extracted DNA was amplified using the AmpFlSTR Profiler Plus, AmpFlSTR COfiler, and the AmpFlSTR Identifiler PCR amplification kits for the detection of the autosomal STR allelic patterns. DNA extracted from the male volunteers and from the soiled tissue paper evidence sample was also amplified using the Y-PLEX 6 and Y-PLEX 5 amplification kits. Analysis of the amplified products was carried out by capillary electrophoresis on the ABI PRISM 310 Genetic Analyzer. Autosomal and Y-STR profiles obtained from the fecal material were concordant with the results from the donors' buccal swabs.     

Maine Caucasian population DNA database using twelve short tandem repeat loci

A population study of Caucasians residing in Maine was conducted using the AmpF1STR Profiler PCR Amplification Kit and the AmpF1STR Profiler Plus PCR Amplification Kit (Applied Biosystems Division (ABD) of Perkin Elmer, Foster City, CA). The kits contain the reagents necessary to amplify 12 different STR loci and the gender marker Amelogenin using two multiplex PCR, each containing nine STR loci. Thus, there is an overlap of six STR loci. The 12 STR loci are TH01, TPOX, CSF1PO, D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, and D7S820. These loci represent 12 of the 13 core loci selected by the CODIS STR standardization project. Dye-labeled amplification products were separated and detected using the capillary electrophoresis instrument ABI Prism 310 Genetic Analyzer. Allele frequencies were determined for the 12 STR loci. Statistical analysis of the data included Hardy-Weinburg equilibrium (HWE) analysis, pairwise independence testing, power of discrimination (PD), and probability of exclusion (PE).     

Validation and casework application of a Y chromosome specific STR multiplex

A series of validation experiments was performed for a Y chromosome specific STR multiplex system following the suggestions made by the Technical Working Group DNA Analysis Methods (TWGDAM). The multiplex PCR products were detected on Perkin-Elmer 373 and 377 automated sequencers using two labeling colors. No problems regarding the stability, robustness and sensitivity of the Y STR multiplex were observed. Mixture studies revealed a cut off rate similar to autosomal STRs for mixtures of male DNAs and no interference of any female admixture. The comparison of the Y STR results to the autosomal typing results for 56 nonprobative semen stains and swabs, showed a slightly higher success rate in detecting the semen donor’s alleles for the Y STR multiplex. Two examples are shown to illustrate the usefulness of Y STR typing for DNA mixtures. In one case the Y STR results confirmed an isolated exclusion; in the other case, the interpretation of a mixture was clarified since the Y STR results proved the presence of DNA from at least two semen donors. Y STR typing is a valuable addition to the forensic DNA testing panel.     

DNA提取方法和PCR循环次数对STR扩增成功率的影响

目的探讨常见载体上的微量血痕DNA的提取方法、PCR循环次数对STR扩增成功率的影响。方法分别应用Chelex-100法及Chelex-100结合纯化法对8种载体上不同大小的血痕样本进行DNA提取,并采用28次、30次及34次PCR循环进行STR扩增,分别观察其扩增成功率。结果经28次、30次及34次PCR循环,Chelex-100法提取DNA后的STR扩增成功率分别为0.2917,0.3333,0.4583,Chelex-100结合纯化法的STR扩增成功率分别为0.3750,0.4583,0.8750。结论用Chelex-100结合纯化法提取DNA,用34次循环扩增可提高STR基因座的检测成功率。