Microarray Assay for Low-Frequency Mutation Detection
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Solution Overview
Problem
Current methods for detecting low-frequency single nucleotide mutations in cancer biopsy samples, such as liquid biopsies, face challenges due to the low abundance of mutant DNA and the need for high sensitivity and specificity, particularly in detecting KRAS gene mutations, which are often time-consuming and costly.
Innovation Solution
A microarray-based assay method using in-tube specific hybridization between single-stranded tagged-PCR products and dual-domain oligonucleotide reporters, combined with surface capture, allows for the detection of KRAS, NRAS, BRAF, and PIK3CA mutations with high sensitivity by isolating and detecting single-stranded DNA on a microarray surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard sequencing techniques (Sanger sequencing or pyrosequencing) are used to detect ctDNA, then the detection can be performed with simple methodology, but the sensitivity is insufficient to detect low-frequency mutations when ctDNA accounts for less than 1% of total circulating free DNA
Solution Approach 1:
The method segments the detection process into distinct stages: (1) enrichment of mutant alleles through COLD-PCR or other pre-enrichment techniques, (2) amplification of enriched products, and (3) sequencing analysis. This segmentation allows each stage to be optimized independently, achieving high sensitivity without requiring complete redesign of the entire workflow.
Solution Approach 2:
The patent applies preliminary enrichment actions before the main sequencing detection. Techniques such as COLD-PCR are performed first to pre-concentrate mutant alleles from the complex background of wild-type DNA and normal cellular DNA, thereby preparing the sample for more effective subsequent detection.
2Measurement precision
If droplet digital PCR (ddPCR) is used to detect mutant alleles with high sensitivity (0.01-0.001%), then the detection sensitivity is improved, but the method lacks multiplexing capability and requires complex droplet generation and counting procedures
Solution Approach 1:
The patent employs universal sequencing primers and protocols that can detect multiple different mutations simultaneously. The same sequencing reaction and analysis pipeline can identify various mutant alleles across different genes (KRAS, NRAS, BRAF, PIK3CA), providing multi-functional detection capability without requiring separate specialized assays for each mutation type.
3Measurement precision
If targeted amplicon sequencing with Next Generation Sequencing (NGS) is used to achieve high sensitivity for ctDNA analysis, then the detection sensitivity is improved, but the cost increases and the processing time extends significantly
Solution Approach 1:
The patent applies partial sequencing coverage focused specifically on known mutation hotspots rather than whole-exome or whole-genome sequencing. By targeting only the critical regions where mutations are most likely to occur (e.g., specific codons in KRAS, NRAS, BRAF), the method achieves sufficient sensitivity for clinical detection while dramatically reducing sequencing depth requirements, processing time, and costs compared to comprehensive NGS approaches.
4Productivity
If microarray based approach is used for high-throughput detection of single nucleotide mutations, then the productivity is improved, but the sensitivity for low-frequency mutations in liquid biopsy samples is insufficient
Solution Approach 1:
The patent performs preliminary enrichment of mutant alleles using COLD-PCR or other pre-enrichment techniques before the microarray detection step. This preliminary action concentrates the rare mutant sequences, ensuring that when the enriched sample is analyzed by microarray, the mutant signals are sufficiently amplified to be detected above the background noise, thereby achieving both high throughput and high sensitivity.
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 method enables the accurate detection of KRAS mutations at low frequencies, improving sensitivity to less than 0.1% mutant DNA in a wild-type background, making it suitable for routine clinical diagnosis and liquid biopsy applications.
Implementation Method 1
hybridize in solution the single strand amplification product with at least one reporter molecule which comprises at least two, different domains of oligonucleotide
Implementation Method 2
contact the solution of the hybridized single strand amplification product with the at least one microarray probe surface which comprises at least one capture probe to allow for hybridization
Data Source
AI summary
An assay for detecting gene fragments, including: amplifying gene fragments comprising single-nucleotide polymorphisms (SNPs) to form an initial amplification product; isolating single strand oligonucleotides of interest from the initial amplification product; forming a solution comprising the oligonucleotides of interest and reporter molecules, each reporter molecule having a first oligonucleotide domain configured to hybridize with a complementary oligonucleotide of interest, and a second oligonucleotide domain configured to hybridize with a complementary capture probe; hybridizing, in the solution, the oligonucleotides of interest with the reporter molecules that have complementary first domains; applying the solution to the surface of a microarray including an array of capture probes fixed to a microarray slide; capturing the oligonucleotides of interest on the microarray by hybridizing the second oligonucleotide domains of the reporter molecules with complementary capture probes of the microarray; and detecting the hybridized oligonucleotides of interest captured on the microarray.