Mismatch-introduced DNA probes constructed on the basis ofthermodynamic analysis enable the discrimination of single nucleotide variants.

Abstract

Genotyping of single nucleotide variants (SNVs) has enabled the assessment of disease-related risk factors and significantly improved the potency of diagnosis and prognosis. Meanwhile, genotyping of SNVs is challenging due to the high sequence similarity between wild-type (WT) and SNV. To increase the discrimination between WT and SNV, probes are modified with nucleic acid analogues such as locked nucleic acid (LNA), or deliberate mismatches are introduced to the probe sequence. However, nucleic acid analogues have limitation in high cost and complexity in their synthesis. And a generalized methodology has not been proposed for determining the position and type of deliberate mismatches at the designated experimental conditions to the best of our knowledge. Herein, we propose a reliable workflow for designing mismatch-introduced probes (MIPs) based on nucleic acid thermodynamic analysis and rejection sampling. The theoretical hybridization state of MIP was calculated using nucleic acid thermodynamics, and the detectability was estimated by rejection sampling that simulates the errors from experimental environments. We fabricated MIPs for SNVs in epidermal growth factor receptor, and experimentally demonstrated optimized detectability. The detectability increased up to 7.19-fold depending on the position and type of mismatch; moreover, the optimized MIP showed higher detectability than the LNA probe. This indicates that the workflow can be broadly applied to the optimization of probe sequence for the detection of various disease-related SNVs.