EGFR Exon 21 Primer Set for L858R Mutation Detection
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Solution Overview
Problem
Current methods for detecting EGFR exon 21 polymorphisms in lung cancer samples, such as direct sequencing and SMAP, face challenges in specificity and complexity, particularly when using soluble DNA from plasma or serum, where existing techniques may not provide sufficient sensitivity or ease of primer design and manipulation.
Innovation Solution
A primer set comprising P1 and P2 oligonucleotides, designed to amplify a region including the 172792nd base of SEQ ID NO: 1, with specific length and melting temperature relationships, and optionally incorporating non-complementary bases or mismatch bases, to enhance specificity and sensitivity for detecting EGFR exon 21 L858R mutations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct sequencing method is used to detect EGFR exon 21 polymorphism, then the detection can be performed with simple procedure, but the specificity is only about 10% which is insufficient for soluble DNA detection
Solution Approach 1:
The invention changes the parameters of the primers by designing specific melting temperature relationships (Tm differences) and incorporating mismatch bases at specific positions. This allows the primer set to preferentially amplify mutant sequences while maintaining simple PCR-based detection procedures, thereby improving specificity without complicating the overall detection method.
2Measurement precision
If SMAP method is used to detect EGFR exon 21 polymorphism, then the sensitivity is sufficient for mutation detection, but the primer design and actual manipulation become complicated
Solution Approach 1:
The invention simplifies primer design by establishing clear parameter guidelines: Tm differences of 0.1-20°C between P1 and P2 oligonucleotides, and specific placement of 1-5 mismatch bases in the P1 oligonucleotide. These defined parameters enable sensitive mutation detection while making primer design systematic and manageable rather than complicated.
Solution Approach 2:
The invention introduces local quality changes by placing mismatch bases at specific local positions within the P1 oligonucleotide (not uniformly distributed). This localized modification at critical positions enhances sensitivity for detecting the specific L858R mutation while keeping the overall primer structure simple and manageable.
3Ease of operation
If both mutant type and wild type primers are used in one reaction to preferentially amplify mutated sequences, then the detection becomes easy and sensitive, but the primer design requires specific Tm relationships and mismatch positioning that increases design complexity
Solution Approach 1:
The invention establishes specific parameter ranges for primer design: Tm differences of 0.1-20°C between P1 and P2, and 1-5 mismatch bases positioned specifically in P1. These defined parameters enable the method to achieve both ease of operation and acceptable design complexity by providing clear design guidelines rather than requiring complex optimization.
Solution Approach 2:
The invention creates a composite primer system where P1 and P2 oligonucleotides work together with specific Tm relationships and mismatch configurations. This composite approach allows preferential amplification of mutant sequences while maintaining manageable design requirements through systematic parameter relationships between the two primer components.
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
The primer set enables high-sensitivity detection of EGFR exon 21 polymorphisms, improving diagnostic accuracy and ease of use by preferentially amplifying mutant-type sequences, thereby aiding in predicting the effectiveness of EGFR tyrosine kinase inhibitors.
Implementation Method 1
the primer set comprising a P1 oligonucleotide and a P2 oligonucleotide and being capable of performing amplification by using a region in SEQ ID NO: 1 as a template
Implementation Method 2
the P1 oligonucleotide and the P2 oligonucleotide satisfying at least one of the following relationships: the melting temperature of the P1 oligonucleotide is higher than the melting temperature of the P2 oligonucleotide
Data Source
AI summary
The invention provides a primer set for detecting a polymorphism in EGFR exon 21 L858R. The primer set has a P1 oligonucleotide and a P2 oligonucleotide and can performing amplification by using a region including the 172792nd base of SEQ ID NO: 1 as a template. As a base that is complementary to the 172792nd base of SEQ ID NO: 1, the P1 oligonucleotide has cytosine and the P2 oligonucleotide has adenine. The melting temperature of the P1 oligonucleotide is higher than the melting temperature of the P2 oligonucleotide, and/or the P1 oligonucleotide is one or more bases longer than the P2 oligonucleotide. The invention further provides a polymorphism detection primer, a polymorphism detection method using the primer set, a method of evaluating a EGFR tyrosine kinase inhibitor using the primer set, a primer used in the polymorphism detection method, and a kit including the primer set.