首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
The high degree of polymorphism at human leukocyte antigen (HLA) class I and class II loci makes high-resolution HLA typing challenging. Current typing methods, including Sanger sequencing, yield ambiguous typing results because of incomplete genomic coverage and inability to set phase for HLA allele determination. The 454 Life Sciences Genome Sequencer (GS FLX) next generation sequencing system coupled with conexio atf software can provide very high-resolution HLA genotyping. High-throughput genotyping can be achieved by use of primers with multiplex identifier (MID) tags to allow pooling of the amplicons generated from different individuals prior to sequencing. We have conducted a double-blind study in which eight laboratory sites performed amplicon sequencing using GS FLX standard chemistry and genotyped the same 20 samples for HLA-A, -B, -C, DPB1, DQA1, DQB1, DRB1, DRB3, DRB4, and DRB5 (DRB3/4/5) in a single sequencing run. The average sequence read length was 250 base pairs and the average number of sequence reads per amplicon was 672, providing confidence in the allele assignments. Of the 1280 genotypes considered, assignment was possible in 95% of the cases. Failure to assign genotypes was the result of researcher procedural error or the presence of a novel allele rather than a failure of sequencing technology. Concordance with known genotypes, in cases where assignment was possible, ranged from 95.3% to 99.4% for the eight sites, with overall concordance of 97.2%. We conclude that clonal pyrosequencing using the GS FLX platform and CONEXIO ATF software allows reliable identification of HLA genotypes at high resolution.  相似文献   

5.

Aim

To apply massively parallel and clonal sequencing (next generation sequencing or NGS) to the analysis of forensic mixed samples.

Methods

A duplex polymerase chain reaction (PCR) assay targeting the mitochondrial DNA (mtDNA) hypervariable regions I/II (HVI/HVII) was developed for NGS analysis on the Roche 454 GS Junior instrument. Eight sets of multiplex identifier-tagged 454 fusion primers were used in a combinatorial approach for amplification and deep sequencing of up to 64 samples in parallel.

Results

This assay was shown to be highly sensitive for sequencing limited DNA amounts ( ~ 100 mtDNA copies) and analyzing contrived and biological mixtures with low level variants ( ~ 1%) as well as “complex” mixtures (≥3 contributors). PCR artifact “hybrid” sequences generated by jumping PCR or template switching were observed at a low level (<2%) in the analysis of mixed samples but could be eliminated by reducing the PCR cycle number.

Conclusion

This study demonstrates the power of NGS technologies targeting the mtDNA HVI/HVII regions for analysis of challenging forensic samples, such as mixtures and specimens with limited DNA.Limited and mixed DNA samples are often encountered in forensic cases and pose both technical and interpretation challenges. The highly polymorphic hypervariable regions I/II (HVI/II) of the mitochondrial genome are often successfully used to analyze limited and/or degraded DNA samples (1). However, there are some limitations to the current standard approaches used for mitochondrial DNA (mtDNA) sequence analysis when mixtures are encountered. In a five year retrospective study of mtDNA analysis of 691 casework hair samples, a mixture of mtDNA sequences attributed to a secondary source was observed in 8.7% of the hairs and sequence heteroplasmy was observed in 11.7% of the cases (2). While approaches that use capillary electrophoresis technologies for Sanger sequencing of mtDNA polymorphic regions allow for detection of mixtures, they do not allow for resolving individual sequences in a mixture (3-10). Mitochondrial DNA markers are ideal targets for detecting mixtures since, with few exceptions, a single sequence per contributor is the expected result due to its haploid nature. However, unlike short tandem repeats (STRs), peak areas or heights in sequence electropherograms are not necessarily indicative of the amount of DNA contributed to a mixture (9,11,12). As a result, peak height ratios for two bases cannot be used to determine the relative proportions of components of a mixture for mtDNA Sanger sequencing analysis. For this reason, Sanger sequencing does not allow for determining the individual mtDNA sequence haplotypes of mixed samples. Therefore, when mixed base calls are encountered during mtDNA Sanger sequence analysis of forensic specimens, most forensic laboratories choose not to interpret the result and categorize mtDNA mixture results as inconclusive for reporting purposes (13). Furthermore, Sanger sequencing cannot detect minor components present at less than 10% in a DNA mixture (9,12).The 454 genome sequencing technology is a scalable, clonal, and highly parallel pyrosequencing system that can be used for de novo sequencing of small whole genomes or direct sequencing of DNA products generated by polymerase chain reaction (PCR). The technology uses emulsion PCR (emPCR) to amplify a single DNA sequence to 10 million identical copies. The “clonal sequencing” aspect of the technology enables separation of individual components of a mixture as well as analysis of highly degraded DNA. The clonal sequencing approach used with the 454 GS technology and other next-generation sequencing (NGS) technologies provides a digital readout of the number of reads or individual sequences allowing for a quantitative determination of the components in a mixture (14). Recently, the potential value of using NGS technologies for forensic applications has been demonstrated (15-18). This article aims to describe a highly sensitive NGS method that uses PCR for targeted enrichment of the HVI/HVII regions of mtDNA for resolving simple and complex mixtures as well as detecting low levels of heteroplasmy.  相似文献   

6.

Background

An accurate tool for human papillomavirus (HPV) typing is important both for management of patients with HPV infection and for surveillance studies.

Objectives

Design and evaluation of an HPV typing method based on 454 next generation sequencing (NGS) technology.

Study design

Development of an HPV typing method based on 454 NGS of HPV L1 amplicons generated with MY09/11-based primers. Evaluation of the NGS method in control samples and in a panel of cervical cytological samples. Comparison of the NGS typing method with cycle sequencing and with the reverse hybridization-based INNO-LiPA HPV Genotyping Extra assay (LiPA).

Results

In control samples carrying mixtures of HPV16 and HPV18 DNA, the NGS method could reliably detect genotype sequences occurring at a frequency of 1% in multiple infections with a sensitivity of 100 genome equivalents/μL. In cervical cytology samples, comparison with cycle sequencing demonstrated accuracy of HPV typing by NGS. The NGS method had however lower sensitivity for some HPV types than LiPA, conceivably due to the poor sensitivity of the MY09/11-based primers. At variance, LiPA could not detect HPV types which were present in low proportion in multiple infections (<10% of HPV reads obtained by NGS). In addition, NGS allowed identifying the presence of different variants of the same HPV type in a specimen.

Conclusions

NGS is a promising method for HPV typing because of its high sensitivity in multiple infection and its potential ability to detect a broad spectrum of HPV types, subtypes, and variants.  相似文献   

7.
8.

Objective

Next Generation Sequencing (NGS) has become a useful tool for gene mutation testing which is required for targeted therapies. The aim of this study was to validate the GeneRead QIAact Actionable Insights Tumor Panel (Qiagen) on the GeneReader System in a diagnostic laboratory setting.

Methods

The GeneRead QIAact Actionable Insights Tumor Panel allows the analysis of 773 variant positions in 12 genes (ALK, BRAF, EGFR, ERBB2, ERBB3, ESR1, KIT, KRAS, NRAS, PDGFRA, PIK3CA and RAF1). For the validation of the panel we used a commercial available multiplex reference standard carrying 11 mutations in defined positions, samples from interlaboratory tests, and FFPE tumor samples from patients which were tested previously for mutations in KRAS, NRAS, BRAF, EGFR, KIT, and/or PDGFRA with pyrosequencing.

Results

Among the 122 tested samples, 121 samples (99.2%) were successfully sequenced. The sensitivity and specificity for detecting variants was 100% and results proved to be reproducible and precise. 119 (98.3%) results were concordant to the expected results. The differences between NGS and pyrosequencing observed in two samples were due to a wrong analysis by the pyrosequencing software which did not cover the present mutations.

Conclusion

Overall, the GeneRead QIAact Actionable Insights Tumor Panel was specific and sensitive for mutation analysis for targeted therapies and can be incorporated into laboratory diagnostics' daily practice.  相似文献   

9.
《Human immunology》2022,83(1):61-69
Chimerism testing provides informative clinical data regarding the status of a biological sample mixture. For years, this testing was achieved by measuring the peaks of informative short tandem repeat (STR) loci using capillary electrophoresis (CE). With the advent of next generation sequencing (NGS) technology, the quantification of the percentage of donor/recipient mixtures is more easily done using sequence reads in large batches of samples run on a single flow cell. In this study, we present data on using a FORENSIC NGS chimerism platform to accurately measure the percentage of donor/recipient mixtures. We were able to detect chimerism to a limit threshold of 1% using both STR and single nucleotide polymorphism (SNP) informative loci. Importantly, a significant correlation was observed between NGS and CE chimerism methods when compared at donor detection ranges from 1% to 10%. Furthermore, 100% accuracy was achieved through proficiency testing over six surveys. Its usefulness was expanded beyond this to help identify suitable donors for solid organ transplant patients using ancestry SNP profiles. In summary, the NGS method provides a sensitive and reliable alternative to traditional CE for chimerism testing of clinical samples.  相似文献   

10.
DNA from archived organs is presumed unsuitable for genomic studies because of excessive formalin-fixation. As next generation sequencing (NGS) requires short DNA fragments, and Uracil-N-glycosylase (UNG) can be used to overcome deamination, there has been renewed interest in the possibility of genomic studies using these collections. We describe a novel method of DNA extraction capable of providing PCR amplicons of at least 400 bp length from such excessively formalin-fixed human tissues. When compared with a leading commercial formalin-fixed DNA extraction kit, our method produced greater yields of DNA and reduced sequence variations. Analysis of PCR products using bacterial sub-cloning and Sanger sequencing from UNG-treated DNA unexpectedly revealed increased sequence variations, compared with untreated samples. Finally, whole exome NGS was performed on a myocardial sample fixed in formalin for 2 years and compared with lymphocyte-derived DNA (as a gold standard) from the same patient. Despite the reduction in the number and quality of reads in the formalin-fixed DNA, we were able to show that bioinformatic processing by joint calling and variant quality score recalibration (VQSR) increased the sensitivity four-fold to 56% and doubled specificity to 68% when compared with a standard hard-filtering approach. Thus, high-quality DNA can be extracted from excessively formalin-fixed tissues and bioinformatic processing can optimise sensitivity and specificity of results. Sequencing of several sub-cloned amplicons is an important methodological step in assessing DNA quality.  相似文献   

11.
《Human immunology》2021,82(11):850-858
The use of Next Generation Sequencing (NGS) to interrogate cell-free DNA (cfDNA) as a transplant diagnostic provides a crucial step in improving the accuracy of post-transplant monitoring of allograft health. cfDNA interrogation provides a powerful, yet minimally invasive, biomarker for disease and tissue injury. cfDNA can be isolated from a variety of body fluids and analyzed using bioinformatics to unlock its origins. Furthermore, cfDNA characteristics can reveal the mechanisms and conditions under which it was generated and released. In transplantation, donor-derived cfDNA monitoring provides a tool for identifying active allograft injury at the time of transplant, infection, and rejection. Multiple detection and interrogation methods for cfDNA detection are now being evaluated for clinical validity and hold the promise to provide minimally invasive, quantitative, and reproducible measures of allograft injury across organ types.  相似文献   

12.
BackgroundThe current widely applied standard method to screen for HIV-1 genotypic resistance is based on Sanger population sequencing (Sseq), which does not allow for the identification of minority variants (MVs) below the limit of detection for the Sseq-method in patients receiving integrase strand-transfer inhibitors (INSTI). Next generation sequencing (NGS) has facilitated the detection of MVs at a much deeper level than Sseq.ObjectivesHere, we compared Illumina MiSeq and Sseq approaches to evaluate the detection of MVs involved in resistance to the three commonly used INSTI: raltegravir (RAL), elvitegravir (EVG) and dolutegravir (DTG).Study designNGS and Sseq were used to analyze RT-PCR products of the HIV-1 integrase coding region from six patients and in serial samples from two patients. NGS sequences were assembled and analyzed using the low frequency variant detection (LFVDT) tool in CLC genomic workbench.ResultsSseq detected INSTI resistance and accessory mutations in three of the patients (called INSTI Res+), while no resistance or accessory mutations were detected in the remaining three patients (called INSTI Res-). Additional INSTI resistance and/or accessory mutations were detected by NGS analysis of integrase sequences from all three INSTI Res+ and one INSTI Res- patient.ConclusionOur observations suggested that NGS demonstrated a higher sensitivity than sSEQ in the identification of INSTI relevant MVs both in patients at treatment baseline and in patients receiving INSTI therapy. Thus NGS can be a valuable tool in monitoring of antiretroviral minority resistance in patients receiving INSTI therapy.  相似文献   

13.
14.
《Human immunology》2015,76(12):910-916
Compared to Sanger sequencing, next-generation sequencing offers advantages for high resolution HLA genotyping including increased throughput, lower cost, and reduced genotype ambiguity. Here we describe an enhancement of the Roche 454 GS GType HLA genotyping assay to provide very high resolution (VHR) typing, by the addition of 8 primer pairs to the original 14, to genotype 11 HLA loci. These additional amplicons help resolve common and well-documented alleles and exclude commonly found null alleles in genotype ambiguity strings. Simplification of workflow to reduce the initial preparation effort using early pooling of amplicons or the Fluidigm Access Array™ is also described. Performance of the VHR assay was evaluated on 28 well characterized cell lines using Conexio Assign MPS software which uses genomic, rather than cDNA, reference sequence. Concordance was 98.4%; 1.6% had no genotype assignment. Of concordant calls, 53% were unambiguous. To further assess the assay, 59 clinical samples were genotyped and results compared to unambiguous allele assignments obtained by prior sequence-based typing supplemented with SSO and/or SSP. Concordance was 98.7% with 58.2% as unambiguous calls; 1.3% could not be assigned. Our results show that the amplicon-based VHR assay is robust and can replace current Sanger methodology. Together with software enhancements, it has the potential to provide even higher resolution HLA typing.  相似文献   

15.
Histological and molecular subtyping of non-small cell lung cancer (NSCLC) is important for predicting survival and drug response in these patients. Up to 8 % of NSCLC are multifocal and these tumor foci are often clonally related. Multiple foci can however also represent different primary tumors, with prognostic and therapeutic consequences. We describe a patient with multifocal NSCLC from which we obtained tissue from two separate lesions. With routine conventional molecular determinations, the clonal relationship between the two lesions was determined. In addition, targeted next generation sequencing with the Ion Torrent Personal Genome Machine (PGM) was performed to explore the accuracy and additional value of this relatively new technique. The two tumors of this patient showed different activating epidermal growth factor receptor (EGFR) mutations, EGFR amplification status, TP53 mutation status, and loss of heterozygosity patterns. With the PGM, all conventional detected mutations were confirmed, and an additional variant of unknown significance in ATM was detected in one of the tumors. The multifocal NSCLC of this patient represents two unrelated primary tumors. Our results suggest that multifocal NSCLC should be considered as potentially multiple primary tumors. As the presence of activating EGFR mutations has important therapeutic consequences, EGFR testing should be performed on all tumor foci present. In the present case, targeted next generation sequencing using the PGM appeared to be accurate and comparable with conventional molecular determinations. However, the application of the PGM in routine pathology molecular diagnostics needs validation in larger series of cases.  相似文献   

16.
Esophageal carcinoma cuniculatum (ECC) is a rare form of extremely well-differentiated squamous cell carcinoma of esophagus that is often misdiagnosed preoperatively. The molecular changes underlying ECC remain unknown. This study aimed to explore the molecular signature of ECC using next-generation sequencing (NGS). Five cases of ECC were collected from our pathology database from 2014 to 2019. One patient received chemoradiation and the remaining four patients were treatment-naïve. Areas of normal squamous mucosa, non-invasive component, and invasive component of ECC were circled and macrodissected. Genomic DNA extracted from the macrodissected tissue was sequenced using GatorSeq NGS Panel. Deleterious mutations, predicted by Sorting Intolerant from Tolerant (SIFT), were identified using tumor/normal pairs and annotated by amino acid change. The normal-appearing squamous mucosa in the ECC harbored recurrent deleterious somatic mutations in ROS1 and POLE genes. ECC tumor-specific deleterious mutations were identified on TP53, NOTCH1, and PIK3CA genes. Our results support a mutually exclusive pattern in NOTCH1 and PIK3CA mutation. Non-invasive and invasive components in ECC had identical mutation profiles. Chemoradiation therapy led to disappearance of NOTCH1 mutation in one ECC case. Our results suggest molecular testing may help pre-operative diagnosis, and provide therapeutic targets in patients with advanced or unresectable ECC.  相似文献   

17.
18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号