Comparison of Three BRAF Mutation Tests in Formalin-Fixed Paraffin Embedded Clinical Samples

BACKGROUND: Recently, BRAF inhibitors showed dramatic treatment outcomes in BRAF V600 mutant melanoma. Therefore, the accuracy of BRAF mutation test is critical. METHODS: BRAF mutations were tested by dual-priming oligonucleotide-polymerase chain reaction (DPO-PCR), direct sequencing and subsequently retested with a real-time PCR assay, cobas 4800 V600 mutation test. In total, 64 tumors including 34 malignant melanomas and 16 papillary thyroid carcinomas were analyzed. DNA was extracted from formalin-fixed paraffin embedded tissue samples and the results of cobas test were directly compared with those of DPO-PCR and direct sequencing. RESULTS: BRAF mutations were found in 23 of 64 (35.9%) tumors. There was 9.4% discordance among 3 methods. Out of 6 discordant cases, 4 cases were melanomas; 3 cases were BRAF V600E detected only by cobas test, but were not detected by DPO-PCR and direct sequencing. One melanoma patient with BRAF mutation detected only by cobas test has been on vemurafenib treatment for 6 months and showed a dramatic response to vemurafenib. DPO-PCR failed to detect V600K mutation in one case identified by both direct sequencing and cobas test. CONCLUSIONS: In direct comparison of the currently available DPO-PCR, direct sequencing and real-time cobas test for BRAF mutation, real-time PCR assay is the most sensitive method.

Evaluation of Multiplex PCR Assay Using Dual Priming Oligonucleotide System for Detection Mutation in the Duchenne Muscular Dystrophy Gene / 대한진단검사의학회지

BACKGROUND: Exon deletions of Duchenne muscular dystrophy (DMD) gene account for most of the alterations found in DMD and Becker muscular dystrophy (BMD). This study was to evaluate the usefulness of dual priming oligonucleotide multiplex PCR (DPO PCR) in detection of exon deletions of DMD gene. METHODS: Thirty-seven DMD or BMD patients who had known exon deletions detected by conventional multiplex PCR (conventional PCR) and nine control subjects were enrolled in this study. When a discrepancy was shown between the results of conventional PCR and DPO PCR, the multiplex ligation-dependent probe amplification (MLPA) technique was performed as a confirmation test. RESULTS: The same deletions previously identified by conventional PCR in 32 out of 37 subjects were also detected by DPO PCR. For the five subjects (13.5%) showing discrepant results between the conventional PCR and DPO PCR, MLPA was performed and its results were found to correlate better with those of DPO PCR. The discrepancies were due to false positive or false negative results of the conventional PCR. CONCLUSIONS: DPO PCR shows a high agreement of results with the conventional PCR and is considered an adequate method to be used as a primary genetic test for the diagnosis of DMD. Because of an improved accuracy, especially for determining the boundaries of DMD gene deletions, DPO PCR can be very useful as a supplement to the conventional PCR.