Dataset Information

Single-Tubed Wild-Type Blocking Quantitative PCR Detection Assay for the Sensitive Detection of Codon 12 and 13 KRAS Mutations.

ABSTRACT: The high degree of intra-tumor heterogeneity has meant that it is important to develop sensitive and selective assays to detect low-abundance KRAS mutations in metastatic colorectal carcinoma (mCRC) patients. As a major potential source of tumor DNA in the aforementioned genotyping assays, it was necessary to conduct an analysis on both the quality and quantity of DNA extracted from formalin-fixed paraffin-embedded (FFPE). Therefore, four commercial FFPE DNA extraction kits were initially compared with respect to their ability to facilitate extraction of amplifiable DNA. The results showed that TrimGen kits showed the greatest performance in relation to the quality and quantity of extracted FFPE DNA solutions. Using DNA extracted by TrimGen kits as a template for tumor genotyping, a real-time wild-type blocking PCR (WTB-PCR) assay was subsequently developed to detect the aforementioned KRAS mutations in mCRC patients. The results showed that WTB-PCR facilitated the detection of mutated alleles at a ratio of 1:10,000 (i.e. 0.01%) wild-type alleles. When the assay was subsequently used to test 49 mCRC patients, the results showed that the mutation detection levels of the WTB-PCR assay (61.8%; 30/49) were significantly higher than that of traditional PCR (38.8%; 19/49). Following the use of the real-time WTB-PCR assay, the ?Cq method was used to quantitatively analyze the mutation levels associated with KRAS in each FFPE sample. The results showed that the mutant levels ranged from 53.74 to 0.12% in the patients analyzed. In conclusion, the current real-time WTB-PCR is a rapid, simple, and low-cost method that permits the detection of trace amounts of the mutated KRAS gene.

SUBMITTER: Huang JF

PROVIDER: S-EPMC4689371 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Single-Tubed Wild-Type Blocking Quantitative PCR Detection Assay for the Sensitive Detection of Codon 12 and 13 KRAS Mutations.

Huang Jun-Fu JF Zeng Dong-Zhu DZ Duan Guang-Jie GJ Shi Yan Y Deng Guo-Hong GH Xia Han H Xu Han-Qing HQ Zhao Na N Fu Wei-Ling WL Huang Qing Q

PloS one 20151223 12

The high degree of intra-tumor heterogeneity has meant that it is important to develop sensitive and selective assays to detect low-abundance KRAS mutations in metastatic colorectal carcinoma (mCRC) patients. As a major potential source of tumor DNA in the aforementioned genotyping assays, it was necessary to conduct an analysis on both the quality and quantity of DNA extracted from formalin-fixed paraffin-embedded (FFPE). Therefore, four commercial FFPE DNA extraction kits were initially compar ...[more]

PMID: 26701781

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Project description:BackgroundApproximately 40% of colorectal cancer (CRC) cases are linked to Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. KRAS mutations are associated with poor CRC prognosis, especially KRAS codon 12 mutation, which is associated with metastasis and poorer survival. However, the clinicopathological characteristics and prognosis of KRAS codon 13 mutation in CRC remain unclear.AimTo evaluate the clinicopathological characteristics and prognostic value of codon-specific KRAS mutations, especially in codon 13.MethodsThis retrospective, single-center, observational cohort study included patients who underwent surgery for stage I-III CRC between January 2009 and December 2019. Patients with KRAS mutation status confirmed by molecular pathology reports were included. The relationships between clinicopathological characteristics and individual codon-specific KRAS mutations were analyzed. Survival data were analyzed to identify codon-specific KRAS mutations as recurrence-related factors using the Cox proportional hazards regression model.ResultsAmong the 2203 patients, the incidence of KRAS codons 12, 13, and 61 mutations was 27.7%, 9.1%, and 1.3%, respectively. Both KARS codons 12 and 13 mutations showed a tendency to be associated with clinical characteristics, but only codon 12 was associated with pathological features, such as stage of primary tumor (T stage), lymph node involvement (N stage), vascular invasion, perineural invasion, tumor size, and microsatellite instability. KRAS codon 13 mutation showed no associations (77.2% vs 85.3%, P = 0.159), whereas codon 12 was associated with a lower 5-year recurrence-free survival rate (78.9% vs 75.5%, P = 0.025). In multivariable analysis, along with T and N stages and vascular and perineural invasion, only codon 12 (hazard ratio: 1.399; 95% confidence interval: 1.034-1.894; P = 0.030) among KRAS mutations was an independent risk factor for recurrence.ConclusionThis study provides evidence that KRAS codon 13 mutation is less likely to serve as a prognostic biomarker than codon 12 mutation for CRC in a large-scale cohort.

Project description:IntroductionMutations in isocitrate dehydrogenase genes IDH1 or IDH2 are frequent in glioma, and IDH mutation status is a strong diagnostic and prognostic marker. Current IDH mutation screening is performed with an immunohistochemistry (IHC) assay specific for IDH1 R132H, the most common mutation. Sequencing is recommended as a second-step test for IHC-negative or -equivocal cases. We developed and validated a new real-time quantitative polymerase chain reaction (PCR) assay for single-step detection of IDH1 R132H and 11 rare IDH1/2 mutations in formalin-fixed paraffin-embedded (FFPE) glioma samples. Performance of the IDH1/2 PCR assay was compared to IHC and Sanger sequencing.ResultsThe IDH1/2 PCR assay combines PCR clamping for detection of 7 IDH1 and 5 IDH2 mutations, and Amplification Refractory Mutation System technology for specific identification of the 3 most common mutations (IDH1 R132H, IDH1 R132C, IDH2 R172K). Analytical sensitivity of the PCR assay for mutation detection was <5% for 11/12 mutations (mean: 3.3%), and sensitivity for mutation identification was very high (0.8% for IDH1 R132H; 1.2% for IDH1 R132C; 0.6% for IDH2 R172K). Assay performance was further validated on 171 clinical glioma FFPE samples; of these, 147 samples met the selection criteria and 146 DNA samples were successfully extracted. IDH1/2 status was successfully obtained in 91% of cases. All but one positive IDH1 R132H-IHC cases were concordantly detected by PCR and 3 were not detected by sequencing. Among the IHC-negative cases (n = 72), PCR detected 12 additional rare mutations (10 IDH1, 2 IDH2). All mutations detected by sequencing (n = 67) were concordantly detected by PCR and 5/66 sequencing-negative cases were PCR-positive (overall concordance: 96%). Analysis of synthetic samples representative of the 11 rare IDH1/2 mutations detected by the assay produced 100% correct results.ConclusionsThe new IDH1/2 PCR assay has a high technical success rate and is more sensitive than Sanger sequencing. Positive concordance was 98% with IHC for IDH1 R132H detection and 100% with sequencing. The PCR assay can reliably be performed on FFPE samples and has a faster turnaround time than current IDH mutation detection algorithms. The assay should facilitate implementation of a comprehensive IDH1/2 testing protocol in routine clinical practice.

Dataset Information

Single-Tubed Wild-Type Blocking Quantitative PCR Detection Assay for the Sensitive Detection of Codon 12 and 13 KRAS Mutations.

Publications

Single-Tubed Wild-Type Blocking Quantitative PCR Detection Assay for the Sensitive Detection of Codon 12 and 13 KRAS Mutations.

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