Snapback Primers for Genotyping via dsDNA Dye Melting
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Solution Overview
Problem
Current DNA analysis methods for disease detection are complex, expensive, and time-consuming, especially when dealing with complex genetic diseases that require the analysis of multiple sequence alterations, and existing genotyping techniques rely on costly fluorescent probes and post-amplification gel separation.
Innovation Solution
The use of Snapback primers that incorporate a 5′-tail of nucleotides on at least one primer for intramolecular hybridization during PCR, allowing for genotyping and mutation scanning using dsDNA dye melting analysis without the need for covalent fluorophores, quenchers, or blockers, thereby simplifying the process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fluorescent probes (TaqMan probes) are used for closed-tube genotyping, then genotyping can be performed in a single tube without post-PCR processing, but the cost increases significantly due to expensive fluorescent dyes and quenchers
Solution Approach 1:
The patent replaces expensive fluorescent probes with inexpensive, unmodified oligonucleotide primers that serve as disposable genotyping reagents. These primers are synthesized without costly fluorescent labels or quenchers, making the genotyping process affordable while maintaining closed-tube simplicity
Solution Approach 2:
The invention extracts and eliminates the expensive fluorescent labeling components from the genotyping system. By removing fluorophores and quenchers from the primer design, the patent achieves cost reduction while preserving the essential genotyping function through alternative detection methods
2Speed
If Scorpion primers with multiple modifications (fluorophore, quencher, blocker) are used, then intramolecular hybridization enables fast genotyping, but the synthesis cost and complexity increase due to three modifications per primer
Solution Approach 1:
The patent removes the fluorophore, quencher, and blocker modifications from Scorpion primers, retaining only the essential intramolecular hybridization capability. This extraction of unnecessary components reduces primer complexity and synthesis cost while preserving fast hybridization kinetics
Solution Approach 2:
The invention uses simple, unmodified oligonucleotide primers that are inexpensive to synthesize. These disposable primers achieve genotyping through basic intramolecular hybridization without requiring costly modifications, making the process economically viable
3Measurement precision
If post-amplification gel separation is used for Snapback SSCP, then mutation scanning can be performed, but the process becomes more complex and time-consuming
Solution Approach 1:
The patent replaces the mechanical gel separation system with a thermal melting analysis system. By using temperature-dependent denaturation and reannealing of intramolecular hairpin structures, the invention achieves mutation detection without requiring physical gel electrophoresis, thereby simplifying the workflow and reducing processing time
4Measurement precision
If multiple fluorescent dyes and functional groups are attached to probes, then specific allele detection is improved, but the cost and synthesis complexity increase significantly
Solution Approach 1:
The patent uses inexpensive, unmodified oligonucleotide primers instead of expensive fluorescently labeled probes. These simple primers are easily synthesized by standard oligonucleotide synthesis methods without requiring costly post-synthesis labeling or purification steps
Solution Approach 2:
The invention extracts and removes all fluorescent dyes and functional groups from the detection system. Allele-specific detection is achieved through the natural base-pairing properties of unmodified nucleotides during intramolecular hybridization, eliminating the need for complex chemical modifications
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 enables rapid, inexpensive, and simultaneous genotyping and mutation scanning, potentially eliminating the need for sequencing in up to 99% of complex genetic disease analysis by using only PCR reagents and a dsDNA dye, while maintaining high resolution and accuracy.
Implementation Method 1
a dsDNA binding dye, wherein the dye is not covalently bound to the first primer
Implementation Method 2
the probe element to hybridize to the locus to form a hairpin
Implementation Method 3
generating a melting curve for the probe element by measuring fluorescence from a dsDNA binding dye as the mixture is heated
Data Source
AI summary
Methods and kits are provided for nucleic acid analysis. In an illustrative method a target nucleic acid is amplified using a first primer and a second primer, wherein the first primer comprises a probe element specific for a locus of the target nucleic acid and a template-specific primer region, and the probe element is 5′ of the template-specific primer region, subsequently allowing the probe element to hybridize to the locus to form a hairpin, generating a melting curve for the probe element by measuring fluorescence from a dsDNA binding dye as the mixture is heated, wherein the dye is not covalently bound to the first primer, and analyzing the shape of the melting curve. Kits may include one or more of the first and second primers, the dsDNA binding dye, a polymerase, and dNTPs.