Cell-Free DNA Rearrangement Detection via Linear Amplification
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Solution Overview
Problem
Current methods are inadequate for rapidly, accurately, and sensitively detecting genomic rearrangements such as gene fusions in cancer DNA, particularly in fragmented and low-concentration samples like cell-free DNA and formalin-fixed paraffin-embedded tissue, due to challenges in probe tiling and capture efficiency.
Innovation Solution
The method involves tagging DNA molecules with adapters, linear amplification using primers with a rearrangement detection barcode, and capturing on a solid support using a non-nucleotide binding partner like biotin, allowing for efficient enrichment and detection of genomic rearrangements without requiring advance knowledge of breakpoint sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capture methods with oligonucleotide baits are used, then gene fusions can be detected in high-quality DNA samples, but the method fails to achieve sufficient sensitivity and accuracy in fragmented and low-concentration samples like cell-free DNA
Solution Approach 1:
The method segments the detection process into distinct stages: (1) capturing DNA fragments with adapters, (2) linear amplification to enrich rare fusion events, and (3) sequencing. This segmentation allows each stage to be optimized independently, particularly enabling the linear amplification step to boost signals from low-concentration samples without introducing the biases of traditional capture methods
Solution Approach 2:
The method performs preliminary linear amplification of captured DNA fragments before sequencing. This preliminary action enriches rare genomic rearrangement events in low-concentration samples, making them detectable with sufficient statistical power. The amplification occurs before any potential loss or degradation could affect the rare fusion fragments
2Adaptability or versatility
If probe tiling is used to cover all possible breakpoint locations in long introns, then comprehensive gene fusion detection is achieved, but the method becomes cost prohibitive and technically challenging
Solution Approach 1:
Instead of using probes to directly capture breakpoint sequences (the traditional approach), the method inverts the strategy by using adapters to capture any DNA fragment and then relying on linear amplification to enrich fusion events. This inversion eliminates the need for complex probe tiling designs while maintaining comprehensive breakpoint coverage
Solution Approach 2:
The adapter-based capture system serves multiple functions: it captures DNA fragments regardless of sequence composition, enables linear amplification of rare events, and works across all possible breakpoint locations. This universal approach replaces the need for location-specific probes, simplifying the overall system while maintaining versatility
3Reliability
If conventional DNA capture and enrichment methods are used, then standard genomic analyses can be performed, but the methods lack the sensitivity to detect rare genomic rearrangements in processed tissue samples and cell-free DNA
Solution Approach 1:
The method introduces linear amplification as an intermediary step between DNA capture and sequencing. This intermediary process selectively amplifies fusion-containing fragments while suppressing background noise from normal DNA, thereby enhancing detection sensitivity without compromising reliability. The amplification acts as a mediator that bridges the gap between low-input samples and the detection threshold
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
This approach enhances the detection of genomic rearrangements in challenging sample types, improving the accuracy and sensitivity of cancer diagnosis and treatment selection by facilitating the identification of gene fusions and other rearrangements in cancer DNA.
Implementation Method 1
capturing on a solid support using a non-nucleotide binding partner like biotin
Data Source
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AI summary
Disclosed are methods of detecting the presence or absence of a genomic rearrangement in which a sample of tagged DNA molecules is divided into aliquots. The isolated molecules are linearly amplified with a set of primers that targeting loci of interest and comprise a rearrangement detection barcode, a sequencing adapter, and a non-nucleotide binding partner, thereby producing a first population of processed DNA, which is then captured on a solid support using binding to the non-nucleotide binding partner and amplified or eluted. A second aliquot is enriched for a second plurality of loci of interest, thereby producing a second population of processed DNA. At least a portion of the amplified and/or eluted first population of processed DNA and at least a portion of the second population of processed DNA are sequenced; and the presence or absence of genomic rearrangement(s) in the first population of processed DNA is detected.