A Novel Approach to Detect IDH Point Mutations in Gliomas Using Nanopore Sequencing: Test Validation for the Clinical Laboratory.

The use of standard next-generation sequencing technologies to detect key mutations in IDH genes for glioma diagnosis imposes several challenges, including high capital cost and turnaround delays associated with the need for batch testing. For both glioma testing and testing in other tumor types where highly specific mutation identification is required, the high-throughput nature of next-generation sequencing limits the feasibility of using it as a primary approach in clinical laboratories. We hypothesized that third-generation nanopore sequencing by Oxford Nanopore Technologies has the capability to overcome these limitations. This study aimed to develop and validate a nanopore-based IDH mutation detection assay for clinical practice using glioma formalin-fixed, paraffin-embedded (FFPE) tissue. Glioma FFPE (n = 66) samples with confirmed IDH gene mutational status were sequenced on the MinION device using an amplicon-based approach. All cases were concordant when compared with the reference results. Limit of blank and limit of detection for the variant allele fraction were 1.5% and 3.3%, respectively, at 500× read depth per gene. Total sequencing cost per sample was CAD$50 to CAD$134 with results being available in 9 to 15 hours. These findings demonstrate that nanopore-sequencing technology can be leveraged to develop low-cost, high-performance clinical sequencing-based assays with quick turnaround times to support the detection of targeted mutations in FFPE tumor tissue.

Quantitative Echocardiographic Assessment and Optimal Criteria for Early Intervention in Asymptomatic Tricuspid Regurgitation.

BACKGROUND: Significant tricuspid regurgitation (TR) is associated with poor outcome and high operative mortality resulting from late presentation. Yet, the optimal timing for intervention is unknown. OBJECTIVES: The purpose of this study was to evaluate the prognostic value of echocardiographic parameters to inform early intervention in asymptomatic TR. METHODS: Using the Cleveland Clinic echocardiography database 2004 to 2018, the authors identified a consecutive cohort of asymptomatic patients with moderate to severe (3+) or severe (4+) TR. Quantitative TR and right heart parameters were retrospectively determined, and their prognostic utility for all-cause mortality was assessed. RESULTS: In 325 asymptomatic patients (mean age: 67.9 years; 79.4% female) with at least 3+ TR, there were 132 deaths (40.6%), with a median survival time of 9.9 years (95% CI: 7.9-12.7 years). By contrast, the median survival time in an age- and sex-matched cohort of symptomatic TR patients was 4.4 years (95% CI: 2.8-5.9 years). Among all the echocardiographic parameters evaluated, right ventricle free wall strain (RVFWS) and tricuspid regurgitant volume (RVol) were the strongest predictors of mortality in asymptomatic TR. The optimal discriminatory thresholds for these parameters were RVFWS <-19% and RVol >45 mL. The 5-year survival rates by number of risk factors (RF) were 93% (95% CI: 86%-96%), 65% (95% CI: 55%-74%), and 38% (95% CI: 26%-49%) for no RF, 1 RF, and both RFs, respectively. Compared with symptomatic TR, mortality was lower for asymptomatic TR with no RF (HR: 0.10; 95% CI: 0.04-0.29) or 1 RF (HR: 0.29; 95% CI: 0.14-0.58), but similar for asymptomatic TR with both RFs (HR: 1.11; 95% CI: 0.56-2.19). CONCLUSIONS: RVFWS and RVol are key prognostic markers that can be serially monitored to inform optimal timing of intervention for severe asymptomatic TR.