Identification of actionable mutations in circulating tumor DNA (ctDNA) enables gene-targeted therapy of solid tumors based on a simple blood test. NGS methods that attach a unique molecular identifier (UMI) to each DNA molecule control for sequencing technical error and thereby reduce variant allele fraction (VAF) limit of detection (LOD) to <0.01% at a cost of 10-20-fold higher sequencing requirement. Importantly, the VAF lower limit of detection (LOD) for analysis of ctDNA specimens does not typically extend below 0.5% due to limits of ctDNA specimen quantity. We previously reported that synthetic internal standard (IS) spike-ins control for site specific technical error to as low as 0.05% while requiring 20-fold less sequencing space. See the poster abstract (#432) presented by Craig et. al. here: AccuGenomics ctDNA NGS QC and less Sequencing_ AACR 2019
