Parallel Primer DNA Rearrangement Detection in Liquid Biopsies
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Solution Overview
Problem
Existing methods for analyzing cell-free DNA in liquid biopsies struggle with low sensitivity and specificity in detecting DNA rearrangements, leading to poor signal-to-noise ratios and missed biomarkers for cancer therapy, particularly in non-invasive liquid biopsies.
Innovation Solution
A method using 5' to 3' exonuclease negative, strand displacement negative DNA polymerase for primer extension, combined with parallel-oriented primers that block extension on wild-type regions and capture moieties, to selectively detect DNA rearrangements and other modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods are used to analyze cell-free DNA in liquid biopsies, then the procedure is non-invasive, but the detection sensitivity and specificity for DNA rearrangements are low resulting in poor signal-to-noise ratios
Solution Approach 1:
The method divides the detection process into multiple selective steps: (1) hybridization of DNA fragments with specific primers targeting rearrangement breakpoints, (2) selective extension only of primers bound to rearranged DNA using 5' exonuclease-negative polymerase, and (3) enrichment of extended products. This segmentation allows each step to contribute to improving signal-to-noise ratio by eliminating non-specific amplification at each stage.
Solution Approach 2:
The invention applies local quality by using 5' exonuclease-negative DNA polymerase specifically for the extension step, which prevents degradation of the primer-template hybrid and maintains the integrity of the rearrangement-specific signal. This localized enzymatic property enhancement improves detection specificity without affecting other steps of the process.
2Measurement precision
If existing methods are used to detect DNA rearrangements, then the analysis covers broad genomic regions, but the selectivity for rearrangements over wild type DNA is poor resulting in significant detection of wild type DNA
Solution Approach 1:
The method extracts and isolates only the rearrangement-specific signal by using primers that hybridize exclusively to rearranged DNA sequences. The 5' exonuclease-negative polymerase further extracts the specific signal by extending only those primers that are properly hybridized to rearrangement breakpoints, while leaving wild-type DNA untouched. This selective extraction dramatically improves rearrangement detection selectivity.
Solution Approach 2:
The invention performs preliminary hybridization of primers to the DNA sample before extension, allowing only rearrangement-specific primers to bind to their target sequences. This preliminary selective binding step ensures that subsequent extension and amplification occur only on rearranged DNA templates, preventing amplification of wild-type DNA and improving overall selectivity.
3Ease of operation
If liquid biopsy methods are used for cancer detection, then the procedure is non-invasive, but the amount of nucleic acids released into body fluids is low and variable
Solution Approach 1:
The method employs self-service by using the limited cell-free DNA present in the sample to drive the entire detection process. The rearrangement-specific primers automatically hybridize to and amplify only the relevant tumor-derived DNA fragments, eliminating the need for additional enrichment steps or larger sample volumes. This self-amplifying approach maximizes the utility of the small amount of nucleic acid available in liquid biopsy samples.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the detection of DNA rearrangements and modifications in cell-free DNA, improving the accuracy of cancer diagnosis and therapy prediction by enriching for relevant biomarkers in liquid biopsies.
Implementation Method 1
contacting the primer-annealed DNA with a 5' to 3' exonuclease negative, strand displacement negative DNA polymerase, thereby producing a primer-extended sample
Implementation Method 2
contacting the DNA with a plurality of primers, wherein the plurality of primers comprises at least two primers that anneal in a parallel orientation to a target region
Data Source
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AI summary
Provided herein is a DNA analysis method for detecting a presence or absence of a DNA molecule that comprises a structural variation, comprising contacting the DNA with at least two primers that anneal in a parallel orientation to a target region and contacting the primer-annealed DNA with a 5' to 3' exonuclease negative, strand displacement negative DNA polymerase.