PNA Probe PCR Clamp for Mutant DNA Detection
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Solution Overview
Problem
Current methods for detecting somatic mutations in clinical samples are inefficient and prone to contamination due to the excess of wild-type DNA, which masks the mutant DNA signal, and require multiple time-consuming and costly procedures.
Innovation Solution
A method using a pair of primers and a detectable peptide nucleic acid (PNA) probe that complements the target sequence without nucleotide variations, where the PNA probe forms a duplex with the target sequence, and the PCR process is conducted at a temperature lower than the melting temperature of the duplex, allowing for the detection of nucleotide variations by melting analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR amplification is used to detect mutant DNA, then the mutant DNA signal can be detected, but the excess of wild-type DNA masks the mutant DNA signal and exhausts essential reagents
Solution Approach 1:
The patent extracts and removes the wild-type DNA signal from the detection system by using a blocking oligonucleotide that specifically binds to and suppresses amplification of wild-type DNA during PCR. This allows the mutant DNA signal to be detected without competition from the abundant wild-type template, effectively separating the detection of mutant and wild-type alleles.
Solution Approach 2:
The blocking oligonucleotide acts as an intermediary molecule that mediates the suppression of wild-type DNA amplification. It binds to the wild-type template and prevents primer annealing or polymerase extension, thereby indirectly protecting the mutant DNA detection process from reagent exhaustion and signal masking by wild-type DNA.
2Measurement precision
If multiple procedures are used to enrich mutant allele or suppress wild-type allele, then mutant DNA detection accuracy improves, but the process becomes time-consuming and costly
Solution Approach 1:
The patent merges the functions of wild-type suppression and mutant detection into a single PCR reaction by incorporating the blocking oligonucleotide directly into the amplification mixture. This eliminates the need for separate enrichment or suppression steps, reducing both time and cost while maintaining high detection accuracy through real-time monitoring of amplification kinetics.
Solution Approach 2:
The blocking oligonucleotide serves multiple functions simultaneously: it suppresses wild-type DNA amplification, enables mutant allele enrichment, and provides a basis for detection through melting curve analysis or other post-PCR methods. This multi-functionality consolidates what would traditionally require multiple separate procedures into a single integrated assay.
3Measurement precision
If multiple transfers and manipulations are performed to enrich or detect mutant DNA, then detection resolution improves, but the risk of contamination increases
Solution Approach 1:
The blocking oligonucleotide performs preliminary suppression of wild-type DNA amplification before the actual detection step. By pre-establishing selective amplification conditions within the closed PCR system, the method eliminates the need for subsequent manipulations such as gel electrophoresis or colony picking that would require opening the system and increase contamination risk.
Solution Approach 2:
The patent replaces mechanical separation methods (such as gel electrophoresis or centrifugation) with a biochemical suppression mechanism using the blocking oligonucleotide. This substitution allows selective enrichment and detection to occur in solution within the closed PCR tube, eliminating the need for mechanical transfers and associated contamination risks while maintaining high resolution through kinetic or thermal analysis.
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 achieves high sensitivity and reproducibility in detecting trace amounts of mutant DNA, even in the presence of a large excess of wild-type DNA, simplifying the detection process and reducing the risk of contamination.
Implementation Method 1
a detectable peptide nucleic acid (PNA) probe that complements the target sequence without nucleotide variations, where the PNA probe forms a duplex with the target sequence
Implementation Method 2
the PCR process is conducted at a temperature lower than the melting temperature of the duplex
Implementation Method 3
the detection of nucleotide variations by melting analysis
Data Source
AI summary
Disclosed herein is a method for determining whether a target polynucleotide sequence contained in a nucleic acid sample has nucleotide variation(s) in a selected region thereof, the steps of which involve the use of a pair of primers that allows the formation of a PCR product having a sequence covering that of the selected region of the target polynucleotide sequence via a PCR process, and a peptide nucleic acid (PNA) that acts as a PCR clamp as well as a sensor probe. Also disclosed herein is a kit for use in determining the presence of nucleotide variation(s) in the target polynucleotide sequence, which includes the pair of primers and the PNA.