Dataset Information

Somatic mutation detection efficiency in EGFR: a comparison between high resolution melting analysis and Sanger sequencing.

ABSTRACT:

Background

High resolution melting curve analysis is a cost-effective rapid screening method for detection of somatic gene mutation. The performance characteristics of this technique has been explored previously, however, analytical parameters such as limit of detection of mutant allele fraction and total concentration of DNA, have not been addressed. The current study focuses on comparing the mutation detection efficiency of High-Resolution Melt Analysis (HRM) with Sanger Sequencing in somatic mutations of the EGFR gene in non-small cell lung cancer.

Methods

The minor allele fraction of somatic mutations was titrated against total DNA concentration using Sanger sequencing and HRM to determine the limit of detection. The mutant and wildtype allele fractions were validated by multiplex allele-specific real-time PCR. Somatic mutation detection efficiency, for exons 19 & 21 of the EGFR gene, was compared in 116 formalin fixed paraffin embedded tumor tissues, after screening 275 tumor tissues by Sanger sequencing.

Results

The limit of detection of minor allele fraction of exon 19 mutation was 1% with sequencing, and 0.25% with HRM, whereas for exon 21 mutation, 0.25% MAF was detected using both methods. Multiplex allele-specific real-time PCR revealed that the wildtype DNA did not impede the amplification of mutant allele in mixed DNA assays. All mutation positive samples detected by Sanger sequencing, were also detected by HRM. About 28% cases in exon 19 and 40% in exon 21, detected as mutated in HRM, were not detected by sequencing. Overall, sensitivity and specificity of HRM were found to be 100 and 67% respectively, and the negative predictive value was 100%, while positive predictive value was 80%.

Conclusion

The comparative series study suggests that HRM is a modest initial screening test for somatic mutation detection of EGFR, which must further be confirmed by Sanger sequencing. With the modification of annealing temperature of initial PCR, the limit of detection of Sanger sequencing can be improved.

SUBMITTER: Joy RA

PROVIDER: S-EPMC7510081 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Publications

Somatic mutation detection efficiency in EGFR: a comparison between high resolution melting analysis and Sanger sequencing.

Joy Reenu Anne RA Thelakkattusserry Sukrishna Kamalasanan SK Vikkath Narendranath N Bhaskaran Renjitha R Krishnan Sajitha S Vasudevan Damodaran D Ariyannur Prasanth S PS

BMC cancer 20200922 1

<h4>Background</h4>High resolution melting curve analysis is a cost-effective rapid screening method for detection of somatic gene mutation. The performance characteristics of this technique has been explored previously, however, analytical parameters such as limit of detection of mutant allele fraction and total concentration of DNA, have not been addressed. The current study focuses on comparing the mutation detection efficiency of High-Resolution Melt Analysis (HRM) with Sanger Sequencing in ...[more]

PMID: 32962681

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Project description:BackgroundMutation scanning provides the simplest, lowest-cost method for identifying DNA variations on single PCR amplicons, and it may be performed before sequencing to avoid screening of noninformative wild-type samples. High-resolution melting (HRM) is the most commonly used method for mutation scanning. With PCR-HRM, however, mutations less abundant than approximately 3%-10% that can still be clinically significant may often be missed. Therefore, enhancing HRM detection sensitivity is important for mutation scanning and its clinical application.MethodsWe used serial dilution of cell lines containing the TP53 exon 8 mutation to demonstrate the improvement in detection sensitivity for conventional-PCR-HRM in the presence of DMSO. We also conducted coamplification at lower denaturation temperature (COLD)-PCR with an extra step for cross-hybridization, followed by preferential denaturation and amplification at optimized critical temperature (full-COLD-PCR), to further enrich low-level mutations before HRM with or without DMSO, and we used droplet-digital PCR to derive the optimal conditions for mutation enrichment. Both conventional PCR-HRM and full-COLD-PCR-HRM with and without DMSO were used for mutation scanning of TP53 exon 8 in cancer samples containing known mutations and myelodysplastic syndrome samples with unknown mutations. Mutations in other genes were also examined.ResultsThe detection sensitivity of PCR-HRM scanning increases 2- to 5-fold in the presence of DMSO, depending on mutation type and sequence context, and can typically detect mutation abundance of approximately 1%. When mutation enrichment is applied during amplification with full-COLD-PCR followed by HRM in the presence of DMSO, mutations with 0.2%-0.3% abundance in TP53 exon 8 can be detected.ConclusionsDMSO improves HRM mutation scanning sensitivity with saturating dyes. When full-COLD-PCR is used, followed by DMSO-HRM, the overall improvement is about 20-fold compared with conventional PCR-HRM.

Project description:OBJECTIVE:To validate the targeted next-generation sequencing (NGS) platform-Ion Torrent PGM for KRAS exon 2 and expanded RAS mutations detection in formalin-fixed paraffin-embedded (FFPE) colorectal cancer (CRC) specimens, with comparison of Sanger sequencing and ARMS-Scorpion real-time PCR. SETTING:Beijing, China. PARTICIPANTS:51 archived FFPE CRC samples (36 men, 15 women) were retrospectively randomly selected and then checked by an experienced pathologist for sequencing based on histological confirmation of CRC and availability of sufficient tissue. METHODS:RAS mutations were detected in the 51 FFPE CRC samples by PGM analysis, Sanger sequencing and the Therascreen KRAS assay, respectively. Agreement among the 3 methods was assessed. Assay sensitivity was further determined by sequencing serially diluted DNA from FFPE cell lines with known mutation statuses. RESULTS:13 of 51 (25.5%) cases had a mutation in KRAS exon 2, as determined by PGM analysis. PGM analysis showed 100% (51/51) concordance with Sanger sequencing (?=1.000, 95% CI 1 to 1) and 98.04% (50/51) agreement with the Therascreen assay (?=0.947, 95% CI 0.844 to 1) for detecting KRAS exon 2 mutations, respectively. The only discrepant case harboured a KRAS exon 2 mutation (c.37G>T) that was not covered by the Therascreen kit. The dilution series experiment results showed that PGM was able to detect KRAS mutations at a frequency of as low as 1%. Importantly, RAS mutations other than KRAS exon 2 mutations were also detected in 10 samples by PGM. Furthermore, mutations in other CRC-related genes could be simultaneously detected in a single test by PGM. CONCLUSIONS:The targeted NGS platform is specific and sensitive for KRAS exon 2 mutation detection and is appropriate for use in routine clinical testing. Moreover, it is sample saving and cost-efficient and time-efficient, and has great potential for clinical application to expand testing to include mutations in RAS and other CRC-related genes.

Project description:BACKGROUND: TILLING (Targeting Induced Local Lesions IN Genomes) is a powerful tool for reverse genetics, combining traditional chemical mutagenesis with high-throughput PCR-based mutation detection to discover induced mutations that alter protein function. The most popular mutation detection method for TILLING is a mismatch cleavage assay using the endonuclease CelI. For this method, locus-specific PCR is essential. Most wheat genes are present as three similar sequences with high homology in exons and low homology in introns. Locus-specific primers can usually be designed in introns. However, it is sometimes difficult to design locus-specific PCR primers in a conserved region with high homology among the three homoeologous genes, or in a gene lacking introns, or if information on introns is not available. Here we describe a mutation detection method which combines High Resolution Melting (HRM) analysis of mixed PCR amplicons containing three homoeologous gene fragments and sequence analysis using Mutation Surveyor software, aimed at simultaneous detection of mutations in three homoeologous genes. RESULTS: We demonstrate that High Resolution Melting (HRM) analysis can be used in mutation scans in mixed PCR amplicons containing three homoeologous gene fragments. Combining HRM scanning with sequence analysis using Mutation Surveyor is sensitive enough to detect a single nucleotide mutation in the heterozygous state in a mixed PCR amplicon containing three homoeoloci. The method was tested and validated in an EMS (ethylmethane sulfonate)-treated wheat TILLING population, screening mutations in the carboxyl terminal domain of the Starch Synthase II (SSII) gene. Selected identified mutations of interest can be further analysed by cloning to confirm the mutation and determine the genomic origin of the mutation. CONCLUSION: Polyploidy is common in plants. Conserved regions of a gene often represent functional domains and have high sequence similarity between homoeologous loci. The method described here is a useful alternative to locus-specific based methods for screening mutations in conserved functional domains of homoeologous genes. This method can also be used for SNP (single nucleotide polymorphism) marker development and eco-TILLING in polyploid species.

Dataset Information

Somatic mutation detection efficiency in EGFR: a comparison between high resolution melting analysis and Sanger sequencing.

Background

Methods

Results

Conclusion

Publications

Somatic mutation detection efficiency in EGFR: a comparison between high resolution melting analysis and Sanger sequencing.

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