Results Of High-resolution Melting Analysis Research Articles

Detection of HBB:c.92+5G>C and HBB:c.108delC mutations in β-thalassemia carriers using high-resolution melting analysis.

The HBB:c.92+5G>C [known as IVSI-5 (GC)] and HBB:c.108delC [known as Cd 35 (del C)] are the β-globin gene mutations that commonly found in Indonesia. Detection of the mutation in the β-thalassemia carriers can be useful to prevent an increase in the number of β-thalassemia patients. High-Resolution Melting Analysis (HRMA) is the method that can detect the mutation rapidly. The aim of this study was to detect HBB:c.92+5G>C and HBB:c.108delC mutations of the β-thalassemia carriers using HRMA. DNA was isolated from blood archive of ten hematologically proved β-thalassemia carriers. Detection of mutations was carried out by HRMA and then confirmed by sequencing. HRMA was performed by using two pairs of specific primers. One pair of primer targeted the region of HBB:c.92+5G>C and the other targeted the region of HBB:c.108delC. The results of detection of mutation using HRMA then were confirmed by sequencing. A specific primer pair covering the region of HBB:c.92+5G>C to HBB:c.108delC were used for sequencing. The results of HRMA showed that the HBB:c.92+5G>C and HBB:c.108delC mutations found in 50% and 30% samples, respectively. The HRMA results can be confirmed by sequencing in all samples. It can be concluded that HRMA can be used to detect HBB:c.92+5G>C heterozygote and HBB:c.108delC heterozygote mutations.

Rapid first-tier genetic diagnosis in patients with Prader-Willi syndrome

According to the international literature, DNA methylation analysis of the promoter region of SNRPN locus is the most efficient way to start genetic investigation in patients with suspected Prader-Willi syndrome. Our aim was to develop a simple, reliable first-tier diagnosis to confirm Prader-Willi syndrome, therefore to compare our self-designed simple, cost-efficient high-resolution melting analysis and the most commonly used methylation-specific multiplex ligation-dependent probe amplification to confirm Prader-Willi syndrome. We studied 17 clinically suspected Prader-Willi syndrome children and their DNA samples. With self-designed primers, bisulfite-sensitive polymerase chain reaction, high-resolution melting analysis and, as a control, methylation-specific multiplex ligation-dependent probe amplification were performed. Prader-Willi syndrome was genetically confirmed in 6 out of 17 clinically suspected Prader-Willi syndrome patients. The results of high-resolution melting analysis and methylation-specific multiplex ligation-dependent probe amplification were equivalent in each case. Using our self-designed primers and altered bisulfite-specific PCR conditions, high-resolution melting analysis appears to be a simple, fast, reliable and effective method for primarily proving or excluding clinically suspected Prade-Willi syndrome cases. Orv Hetil. 2018; 159(2): 64-69.

Impact of fixation artifacts and threshold selection on high resolution melting analysis for KRAS mutation screening

IntroductionTreatment in metastatic colorectal cancer (mCRC) has expanded with monoclonal antibodies targeting epidermal growth factor receptor, but is restricted to patients with a wild-type (WT) KRAS mutational status. The most sensitive assays for KRAS mutation detection in formalin-fixed paraffin embedded (FFPE) tissues are based on real-time PCR. Among them, high resolution melting analysis (HRMA), is a simple, fast, highly sensitive, specific and cost-effective method, proposed as adjunct for KRAS mutation detection. However the method to categorize WT vs mutant sequences in HRMA is not clearly specified in available studies, besides the impact of FFPE artifacts on HRMA performance hasn't been addressed either. MethodsAvowedly adequate samples from 104 consecutive mCRC patients were tested for KRAS mutations by Therascreen™ (FDA Validated test), HRMA, and HRMA with UDG pre-treatment to reverse FFPE fixation artifacts. Comparisons of KRAS status allocation among the three methods were done. Focusing on HRMA as screening test, ROC curve analyses were performed for HRMA and HMRA-UDG against Therascreen™, in order to evaluate their discriminative power and to determine the threshold of profile concordance between WT control and sample for KRAS status determination. ResultsComparing HRMA and HRMA-UDG against Therascreen™ as surrogate gold standard, sensitivity was 1 for both HRMA and HRMA-UDG; and specificity and positive predictive values were respectively 0.838 and 0.939; and 0.777 and 0.913. As evaluated by the McNemar test, HRMA-UDG allocated samples to a WT/mutated genotype in a significatively different way from HRMA (p > 0.001). On the other hand HRMA-UDG did not differ from Therascreen™ (p = 0.125). ROC-curve analysis showed a significant discriminative power for both HRMA and HRMA-UDG against Therascreen™ (respectively, AUC of 0.978, p > 0.0001, CI 95% 0.957–0.999; and AUC of 0.98, p > 0.0001, CI 95% 0.000–1.0). For HRMA as a screening tool, the best threshold (degree of concordance between sample curves and WT control) was attained at 92.14% for HRMA (specificity of 0.887), and at 92.55% for HRMA-UDG (specificity of 0.952). ConclusionsHRMA is a highly sensitive method for KRAS mutation detection, with apparently adequate and statistically significant discriminative power. FFPE sample fixation artifacts have an impact on HRMA results, so for HRMA on FFPE samples pre-treatment with UDG should be strongly suggested. The choice of the threshold for melting curve concordance has also great impact on HRMA performance. A threshold of 93% or greater might be adequate if using HRMA as a screening tool. Further validation of this threshold is required.

First report of Tasmanian sheep strain (G2) genotype isolated from Iranian goat using the high resolution melting (HRM) analysis.

The present study was aimed to evaluate E. granulosus genotypes isolated from goats using HRM analysis in Isfahan province. Cystic echincoccosis, so-called hydatidosis, is widespread infection caused by the larval stage of Echinococcus granulosus. This is an important zoonotic disease worldwide, especially in the developing countries such as Iran. To date, molecular studies mainly based on the mitochondrial DNA sequences have identified distinct genotypes termed G1-G10 which can differ in some characteristics such as the growth and infectivity to different intermediate hosts or the survival rate in the definitive hosts that are important for the development of control strategies. From August to December 2014, 1341 goats were investigated and hydatid cysts were collected from the liver and lungs of 43 infected goats in Isfahan province abattoirs, Isfahan, Iran. Total genomic DNA was extracted from each sample, amplified for the presence of polymorphism of mitochondrial gene coding for cytochrome c oxidase subunit 1 (CO1), using high resolution melting curve (HRM) method. the results of HRM analysis using the sequence of CO1 gene for 43 Echinococcus granulosus isolates from goats showed 31, 2 and 10 isolates were identified as G1, G2, and G3 genotypes, respectively. G1 is the predominant genotype in the isolated goat samples in Isfahan province, and the presence of G2 strain was reported for the first time in goat in Iran.

The prognostic implication of SRSF2 mutations in Chinese patients with acute myeloid leukemia.

Recently, somatic mutations in SRSF2 gene have been discovered in a proportion of hematologic malignancies including acute myeloid leukemia (AML). This study was aimed to investigate SRSF2 mutations in Chinese AML patients. High-resolution melting analysis (HRMA) was developed to screen SRSF2 mutations in 249 cases with AML, and then direct DNA sequencing was used to verify the results of HRMA. In this study, 3.6% (9/249) of Chinese AML patients were found with heterozygous SRSF2 mutations. Patients with SRSF2 mutations were older than those with wild-type SRSF2 (P = 0.014). No differences in the sex, blood parameters, French-American-British classification (FAB) subtypes, and karyotypes were observed between AML patients with and without SRSF2 mutations. Although the overall survival (OS) of SRSF2-mutated patients was inferior to those without mutations in both whole AML patients (median 4 vs. 11months, respectively; P = 0.006) and cytogenetically normal patients (median 2 vs. 12months, respectively; P = 0.008), multiple analysis disclosed that SRSF2 mutation was not an independent prognostic factor in AML patients. These results suggest that SRSF2 mutation occurs at a low frequency in aged AML patients and might not be associated with adverse prognosis in Chinese AML patients.

Developing and Evaluating the HRM Technique for Identifying Cytochrome P450 2D6 Polymorphisms.

Cytochrome P450 2D6 is one of the important enzymes involved in the metabolism of many widely used drugs. Genetic polymorphisms of CYP2D6 can affect its activity. Therefore, an efficient method for identifying CYP2D6 polymorphisms is clinically important. We developed a high-resolution melting (HRM) analysis to investigate CYP2D6 polymorphisms. Genomic DNA was extracted from peripheral blood samples from 71 healthy individuals. All nine exons of the CYP2D6 gene were sequenced before screening by HRM analysis. This method can detect the most genotypes (*1, *2, *4, *10, *14, *21 *39, and *41) of CYP2D6 in Chinese. All samples were successfully genotyped. The four most common mutant CYP2D6 alleles (*1, *2, *10, and *41) can be genotyped. The single nucleotides polymorphism (SNP) frequencies of 100C > T (rs1065852), 1039C > T (rs1081003), 1661G > C (rs1058164), 2663G > A (rs28371722), 2850C > T (rs16947), 2988G > A (rs28371725), 3181A > G, and 4180G > C (rs1135840) were 58%, 61%, 73%, 1%, 13%, 3%, 1%, 73%, respectively. We identified 100% of all heterozygotes without any errors. The two homozygous genotypes (1661G > C and 4180G > C) can be distinguished by mixing with a known genotype sample to generate an artificial heterozygote for HRM analysis. Therefore, all samples could be identified using our HRM method, and the results of HRM analysis are identical to those obtained by sequencing. Our method achieved 100% sensitivity, specificity, positive prediction value and negative prediction value. HRM analysis is a nongel resolution method that is faster and less expensive than direct sequencing. Our study shows that it is an efficient tool for typing CYP2D6 polymorphisms.

High resolution melting analysis for detecting of JAK2V617F mutation in patients with myeloproliferative neoplasms

This study was purposed to investigate the feasibility of high resolution melting (HRM) in the detection of JAK2V617F mutation in patients with myeloproliferative neoplasm (MPN). The 29 marrow samples randomly selected from patients with clinically diagnosed MPN from January 2008 to January 2011 were detected by HRM method. The results of HRM analysis were compared with that detected by allele specific polymerase chain reaction (AS-PCR) and DNA direct sequencing. The results showed that the JAK2V617F mutations were detected in 11 (37.9%, 11/29) cases by HRM, and its comparability with the direct sequencing result was 100%. While the consistency of AS-PCR with the direct sequencing was moderate (Kappa = 0.179, P = 0.316). It is concluded that the HRM analysis may be an optimal method for clinical screening of JAK2V617F mutation due to its simplicity and promptness with a high specificity.

DNA from buccal swab is suitable for rapid genotyping of angiotensin-converting enzyme insertion/deletion (I/D) polymorphism

BackgroundPlasma angiotensin-converting enzyme (ACE) variability between individuals is the results of an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene. The I and D alleles differ for the presence or absence of a 288bp Alu sequence DNA fragment. MethodsThe present paper regards the development of a single-tube High Resolution Melting Analysis (HRMA), applied to DNA extracted by buccal swabs, for determining three ACE I/I, I/D, D/D genotypes, in order to obtain a rapid and high throughput method. This method takes advantage of the presence of the 288bp DNA fragment. Primer design was performed taking into account the possible different efficiency of allele I amplification compared to allele D, avoiding the misclassification of I/D with D/D genotypes. Results50 samples previously genotyped by “conventional” PCR protocol already published in literature were 100% concordant with the HRMA results, showing high reproducibility, sensitivity and specificity. ACE genotypes were distinguished by normalized temperature melting curves and by derivate fluorescence plots. ConclusionsHRMA was confirmed as particularly suitable for the identification of ACE I/D polymorphism. Simple setup and rapidity of the analysis (about 1.5h for 96 samples, including data interpretation) are other important advantages along with low-costs, making this technique useful in clinical research and diagnostics.

High resolution melting analysis as a tool to detect molecular markers of antiviral resistance in influenza A viruses

A real-time PCR followed by high resolution melting analysis (HRMA) was developed, for rapid detection of antiviral resistance markers in influenza A viruses, of both H1N1 and H3N2 subtypes. The targets of these assays were the nucleotide substitution G806A (S31N mutation) in the M gene as marker of resistance to adamatanes in influenza viruses A(H3N2), the substitution A356T (E119V mutation) in the N2 gene of influenza viruses A(H3N2) and the substitution C823T (H274Y mutation) in the N1 gene of the pandemic A(H1N1) 2009 virus as markers of oseltamivir resistance. First, the designed primers and the overall protocol of the HRMA were validated using already characterized viral isolates either containing or lacking changes at the tested codons. Then, HRMA was used to search for the marker of oseltamivir resistance in 75 clinical samples, H1N1 2009 positives, analyzed previously by pyrosequencing and Sanger sequencing, and of both adamantane-derivatives and oseltamivir resistance in 57 H3N2 positive clinical samples. The results of HRMA of the H1N1 2009 isolates were in agreement with those obtained by sequencing. As regards the H3N2 isolates, HRMA revealed a widespread resistance to adamantanes with 89.5% nucleotide substitution G806A, while 3% were resistant to oseltamivir (A356T change).HRMA, applied to the detection of markers of resistance to antiviral drugs against influenza A viruses, confirmed to be a procedure flexible, low cost and time-saving, suitable for application to epidemiological surveys and in clinical settings for diagnostic purposes.

Development of high-resolution melting analysis for the detection of the MYD88 L265P mutation

ObjectiveRecurrent L265P mutation of myeloid differentiation primary response gene 88 (MYD88) has been identified in a proportion of diffuse large B-cell lymphoma (DLBCL) and chronic lymphocytic leukemia. The present study aimed to establish a rapid, sensitive, and reliable method using high-resolution melting analysis (HRMA) to detect MYD88 L265P mutation in DLBCL. Designs and methodsThe sensitivity of HRMA in the detection of MYD88 L265P mutation was evaluated. MYD88 L265P mutation was further screened in 120 patients with DLBCL. The results of HRMA were validated by direct DNA sequencing. ResultsFor the detection of MYD88 L265P mutation, the reproducible maximal sensitivity of HRMA was 5% higher than that obtained by direct DNA sequencing (25%). Heterozygous MYD88 L265P mutations were identified in 11 (9.2%) DLBCL cases, all of which were diagnosed as non-germinal-center B cell (non-GCB) DLBCL. ConclusionsThe HRMA assay is a rapid, sensitive, reliable, and high-throughput method to screen MYD88 L265P mutation and could be used in clinical diagnostic laboratories.

High Resolution Melting Analysis of the Cytochrome Oxidase I Gene Identifies Three Haplotypes of the Potato Psyllid in the United States

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a vector of the bacterium “Candidatus Liberibacter solanacearum,” the putative causal agent of potato zebra chip disease that has seriously affected the potato industry in the Central and Southwestern United States for the past decade. The 2011 potato growing season saw the first report of zebra chip disease in Washington, Oregon, and Idaho; however, B. cockerelli has been recorded in this region every season at least for the past 7 yr. Studies were conducted to determine the relationship between psyllids collected from the Pacific Northwest potatoes in 2011 and those from the Southwestern and Central United States. High resolution melting analysis of the B. cockerelli mitochondrial Cytochrome C Oxidase subunit I-like gene was conducted on over 450 psyllids collected from numerous locations across the Central and Western United States. Results suggest that at least three potato psyllid haplotypes exist in the United States, correlating to the Central, Western, and Northwestern United States geographical regions. The high resolution melting analysis results were subsequently supported by DNA sequencing data.

Abstract 2103: High resolution melting analysis: a sensitive screening method for the detection of MDM2 promotor SNP309

Abstract Background: Murine double minutes-2 (MDM2) protein plays a key role in physiological processes like growth arrest, senescence and apoptosis. MDM2 negatively regulates key proteins like p53 by inhibiting its transcriptional activity and promoting its proteosomal degradation through ubiquitinylation. In turn, the MDM2 expression is regulated in part by a p53-responsive promotor. This negative feedback control mechanism assures that both p53 and MDM2 are kept at very low levels in proliferating cells. However, in about half of all human tumors, the normal regulation of p53 might be disrupted through direct overexpression of MDM2 caused by e.g. MDM2 gene amplification or a T to G substitution (SNP309) in the promotor region of MDM2. High resolution melting analysis (HRMA) provides a valid approach to efficiently detect DNA mutations. The current study aimed at validating and implementing HRMA for screening of colorectal cancer patients (CRC) to detect MDM2 promotor SNP309. Pyrosequencing was used to confirm and characterize HRMA results. Materials and Methods: First, HRMA sensitivity was established using a cell line and a FFPE (formalin-fixed paraffin embedded) dilution model. Then, the sensitivity of pyrosequencing to detect MDM2 promotor SNP309 was evaluated using the same dilution models. Next, HRMA was validated on 10 cell lines. Since the MDM2 SNP309 status for these cell lines was unavailable, all HRMA results were confirmed and characterized by pyrosequencing. Results: The cell line dilution model revealed a detection limit of 6% while the detection limit in a background of FFPE wild-type DNA was found to be 3%. The detection limit of pyrosequencing to analyze SNP309 in a background of wild-type cell line DNA seems to be between 20% and 15%. In a background of FFPE wild-type DNA, the detection limit seems to be 3%. HRMA revealed abnormal melting patterns in 5/10 cell lines and pyrosequencing confirmed the presence of 2 homozygous (G/G) and 3 heterozygous (G/T) genotypes. Preliminary results on FFPE material from CRC patient samples showed abnormal melting patterns in 6/13 samples. These are currently being confirmed using pyrosequencing. Discussion: HRMA was found to be a fast, efficient, sensitive and reproducible screening method for MDM2 promotor SNP309 detection with a detection limit between 3% and 6%, which is higher than that of conventional sequencing methods. Preliminary results indicate that HRMA can be used as a screening method for MDM2 SNP309 by which DNA from FFPE tissues can be tested. Currently, a cohort of CRC patients is being tested for the presence of SNP309 using HRMA and pyrosequencing. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2103. doi:1538-7445.AM2012-2103

Diagnosis of Spinal Muscular Atrophy Via High-Resolution Melting Analysis Symmetric Polymerase Chain Reaction Without Probe: A Screening Evaluation forSMN1Deletions and Intragenic Mutations

Spinal muscular atrophy (SMA) is a well-defined autosomal recessive neuromuscular disorder caused by mutations in the survival motor neuron 1 (SMN1) gene. The most frequently observed mutation is a deletion of exon 7, which has been documented in >95% of SMA patients. A novel technique for detecting mutations known as high-resolution melting analysis (HRMA) has rapidly become the tool of choice for screening pathogenic genetic variants. In the present study, we attempt to validate the applicability of HRMA to the detection of exon 7 deletions and other intragenic mutations in SMN1. Three primer sets were adopted in our HRMA screening for deletion of SMN1 exon 7. In screening attempts utilizing two primer sets, the results of HRMA were not compatible with those obtained by polymerase chain reaction-restriction fragment length polymorphism. Therefore, we applied a modified protocol using revised primer sets, which resulted in an absolute compatibility of results between HRMA and polymerase chain reaction-restriction fragment length polymorphism. With regard to screenings for intragenic mutations in SMN1 exon 3, two primer sets were adopted for use in HRMA. In the initial HRMA screening using the first primer set, we failed to identify any intragenic mutations; however, when using a revised primer set, HRMA successfully detected the presence of a c.275G>C mutation. HRMA is a simple but versatile tool to add to the existing arsenal of diagnostic techniques that could aid clinicians/researchers in diagnosing SMA. However, as we demonstrate in the present study, the design and selection of primers is of monumental importance in ensuring the successful application of HRMA to screening for pathogenic variants.

Rapid and reliable detection of IDH1 R132 mutations in acute myeloid leukemia using high-resolution melting curve analysis

Objective The mutations of isocitrate dehydrogenase 1 (IDH1) gene have been identified in a proportion of hematologic malignancies including acute myeloid leukemia (AML). The aim of the present study was to explore the reliability of the high-resolution melting analysis (HRMA) for the identification of IDH1 R132 mutations in AML. Designs and methods We evaluated the sensitivity of HRMA in the detection of IDH1 R132 mutation and screened IDH1 mutations in 110 AML patients using HRMA. The results of HRMA were validated by direct DNA sequencing. Results The reproducible sensitivity of HRMA was 5% for the detection of IDH1 R132 mutation, higher than 10% of direct DNA sequencing. Heterozygous IDH1 mutations were identified in 4 (3.6%) AML cases, which were R132H in 3 cases and R132S in 1 case confirmed by DNA sequencing. Conclusion The HRMA is a rapid, accurate, reliable, high-throughput method to screen IDH1 gene mutations.

Rapid and Efficient Detection of EGFR Mutations in Problematic Cytologic Specimens by High-Resolution Melting Analysis

Chemotherapy for advanced non-small-cell lung cancer (NSCLC) remains marginally effective, with a 5-year overall survival rate of approximately 5%. Recently, the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib was approved in Slovakia for the treatment of metastatic NSCLC. Gefitinib is a selective EGFR inhibitor that binds to the adenosine triphosphate binding pocket of the kinase domain and blocks downstream signaling pathways. Mutations of the EGFR gene, particularly an in-frame 15 bp deletion (delE746_A750) in exon 19 and the L858R mutation in exon 21, correlate with enhanced clinical responsiveness to EGFR tyrosine kinase inhibitors. However, the detection of these mutations and thereby prediction of the therapy outcome is sometimes unreliable due to the low sensitivity of direct sequencing if the proportion of tumor cells in the tissue is less than 25%. Therefore we decided to test the applicability of other methods, particularly high-resolution melting analysis (HRMA), for detection of these mutations in clinical samples. We analyzed 53 archival cytologic specimens for the presence of EGFR mutations, using the HRMA method. Results were verified by direct sequencing. For samples containing less than 25% tumor cells, we used mutant-enriched PCR before sequencing. We also performed a titration assay to establish the lower limit of the proportion of tumor cells for detection of EGFR mutations. EGFR mutations were detected in 13 cases (24%). In-frame deletions in exon 19 were detected in eight cases (15%) and the L858R mutation in exon 21 was detected in five cases (9%). The positive results of the HRMA were confirmed by direct sequencing only in five of 13 cases. In the remaining eight positive samples, HRMA results were confirmed by sequencing analysis after mutant-DNA enrichment. The titration assay established that the lower limit for detection of EGFR mutations by HMRA was 1% tumor cells in the clinical sample. Our results indicated that HRMA in combination with mutant-enriched PCR represents a sensitive method for detection of EGFR mutations from cytologic specimens. When properly executed, this protocol allows identification of EGFR mutations in specimens containing a minimal percentage of tumor cells.

Abstract 2122: KRAS mutation detection using high resolution melting analysis and its prognostic value in archival colorectal cancer tissues

Abstract Introduction: The development of targeted therapies has created a pressing clinical need for the rapid and robust molecular characterization of cancers. High resolution melting analysis (HRMA) provides a valid approach to efficiently detect DNA mutations. In the current study, HRMA was validated and implemented for screening of 164 colorectal cancer (CRC) patients to detect hot spot mutations (codon 12/13) in the KRAS oncogene. Direct sequencing was used to confirm and characterize HRMA results. In addition, the prognostic potential of KRAS in CRC was evaluated. Materials and Methods: Initially, the HRMA sensitivity was established using a cell line dilution model, enabling us to detect 3% mutant DNA in a background of wildtype DNA. Next, HRMA was validated on 7 cell lines with or without a known KRAS mutation. All mutations were readily detectable using HRMA. Subsequently, inter- and intravariation was analyzed. Results: HRMA revealed abnormal melting patterns in 57/164 (34.8%) CRC samples with G12D substitution the most prevalent type. However, only 50/164 (30.5%) samples could be confirmed by sequencing. The presence of KRAS mutation was associated with proximal location, advanced stage and microsatellite stability (MSS). Kaplan-Meier survival analysis revealed a significantly shorter overall and disease free survival for CRC patients harboring a KRAS mutation, especially for the G12C substitution. In Cox regression, KRAS mutation was still found to be a negative predictor of survival, however, significance was lost. Conclusions: In conclusion, HRMA was found to be a fast, efficient and reproducible screening method for KRAS mutation detection by which degraded DNA from formalin-fixed, paraffin-embedded tissues can be tested. Additionally, accurate detection of KRAS mutations in CRC shows potential as a prognostic marker and evidence is accumulating that poor outcome could be linked to specific mutations. These results might have an impact on patient selection for adjuvant treatment. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2122.

Prospective Study of the Accuracy of EGFR Mutational Analysis by High-Resolution Melting Analysis in Small Samples Obtained from Patients with Non–Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) mutations, especially in-frame deletions in exon 19 (DEL) and a point mutation in exon 21 (L858R), predict gefitinib sensitivity in patients with non-small cell lung cancer (NSCLC). In this study, we verified the accuracy of EGFR mutation analysis in small samples by high-resolution melting analysis (HRMA), which is a rapid method using PCR amplification with a dye to analyze the melting curves in NSCLC. We designed a prospective study to compare the sensitivity and specificity of HRMA and DNA sequencing with laser capture microdissection. Eligible patients with lung lesions were screened by bronchoscopy or percutaneous needle biopsy to histologically confirm the diagnosis, followed by surgical resection of the NSCLC. Small diagnostic specimens were analyzed for EGFR mutations by HRMA, and the surgically resected specimens were examined for mutations by HRMA and DNA sequencing. The analyses for EGFR mutations were conducted in 52 eligible cases of the 92 enrolled patients. EGFR mutations were detected in 18 (34.6%) patients. The results of HRMA from surgically resected specimens as well as DNA sequencing revealed 100% sensitivity and specificity. On the other hand, the sensitivity and specificity of HRMA from the small diagnostic specimens were 83.3% and 100%, respectively. In this study, we showed that HRMA is a highly accurate method for detecting DEL and L858R mutations in patients with NSCLC, although it is necessary to consider the identification of patients with a false-negative result when the analysis is conducted using small samples.

High-Resolution Melting Analysis for Rapid Detection ofKRAS, BRAF,andPIK3CAGene Mutations in Colorectal Cancer

High-resolution melting analysis (HRMA) provides a valid approach to efficiently detect DNA genetic and somatic mutations. In this study, HRMA was used for the screening of 116 colorectal cancers (CRCs) to detect hot-spot mutations in the KRAS and BRAF oncogenes. Mutational hot spots on the PIK3CA gene, exons 9 and 20, were also screened. Direct sequencing was used to confirm and characterize HRMA results. HRMA revealed abnormal melting profiles in 65 CRCs (56.0%), 16 of them harboring mutations in 2 different genes simultaneously. The frequency of mutations was 17.2% for PIK3CA (11.2% in exon 9 and 6.0% in exon 20), 43.1% for KRAS exon 2, and 9.5% in exon 15 of the BRAF gene. We found a significant association between PIK3CA and KRAS mutations (P = .008), whereas KRAS and BRAF mutations were mutually exclusive (P = .001). This report describes a novel approach for the detection of PIK3CA somatic mutations by HRMA.