Ultrasensitive detection of NOTCH1 delCT mutations in chronic lymphocytic leukemia by ddPCR reveals high frequency of subclonal mutations and predicts clinical outcome in cases with trisomy 12

Publication date: Available online 6 February 2020Source: The Journal of Molecular DiagnosticsAuthor(s): Catherine Hoofd, Steven J. Huang, Samuel Gusscott, Sonya Lam, Rachel Wong, Alexa Johnston, Susana Ben-Neriah, Christian Steidl, David W. Scott, Helene Bruyere, Tanya L. Gillan, Cynthia L. Toze, Alina S. Gerrie, Andrew P. WengAbstractNOTCH1 is recurrently mutated in chronic lymphocytic leukemia (CLL), most commonly as a two base-pair frameshift deletion (c.7541_7542delCT). This mutated allele encodes a truncated form of the receptor (P2514fs*4) lacking the C-terminal PEST degradation domain, and results in increased NOTCH1 signaling duration. NOTCH1 mutation has been associated with poor clinical outcomes in CLL. We sought to validate a highly sensitive and quantitative droplet digital PCR (ddPCR) assay for the NOTCH1 delCT mutation which we anticipated would perform well as compared to Sanger sequencing and allele-specific PCR.Performance characteristics of this assay were tested on 126 samples from an unselected CLL cohort, and a separate cohort of 85 samples from patients with trisomy 12 CLL. The delCT mutation was detected at allele frequencies as low as 0.024% and found 25% of unselected cases and 55% of trisomy 12 cases were positive at the 0.024% detection threshold. Mutational burdens ≥1% were found to be significantly associated with shorter overall survival (OS) in patients with trisomy 12+ disease in multivariate analysis (median OS 9.1 vs. 13 years with hazard...
Source: The Journal of Molecular Diagnostics - Category: Pathology Source Type: research