MOMA Primer Design for Donor-Specific DNA Detection
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Solution Overview
Problem
Current methods are inadequate for accurately quantifying low-frequency non-native nucleic acids in heterogeneous samples, particularly in the context of transplant rejection monitoring, where detecting donor-specific cell-free DNA at low concentrations is crucial for predicting rejection risk.
Innovation Solution
The use of multiplexed optimized mismatch amplification (MOMA) techniques, which design primers with a 3' penultimate mismatch for specific sequence amplification, allowing for the quantitative determination of non-native DNA even at concentrations below 1% or 0.5% in a sample, by employing primer pairs with a 3' double mismatch relative to alternate sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional amplification methods are used, then the detection method is simple, but the measurement precision for low-frequency non-native nucleic acids deteriorates
Solution Approach 1:
The patent applies local quality by introducing a 3' penultimate mismatch specifically at the penultimate position of the primer, rather than uniformly modifying the entire primer sequence. This localized modification creates selective amplification bias against non-native alleles while maintaining overall primer functionality, enabling precise detection of low-frequency non-native nucleic acids without requiring complete redesign of the amplification system.
Solution Approach 2:
The patent changes the chemical parameter of the primer sequence by introducing a mismatch at a specific position (3' penultimate). This parameter change alters the binding affinity and amplification efficiency in a controlled manner, creating sufficient discrimination between native and non-native sequences to detect low-frequency variants (0.5-2%) while maintaining amplification of the dominant native sequence.
2Measurement precision
If conventional amplification methods are used, then the assay procedure is simple, but the measurement precision for donor-specific cell-free DNA deteriorates
Solution Approach 1:
The patent introduces a localized 3' penultimate mismatch in the primer design, which creates selective amplification bias against non-native alleles. This localized modification enables precise quantification of donor-specific cell-free DNA at levels as low as 0.5-2% without requiring complex multi-step procedures, as the specificity is built into the primer structure itself.
3Reliability
If standard PCR primers are used, then the amplification is non-specific, but the primer design is simple
Solution Approach 1:
The patent achieves high amplification specificity by introducing a 3' penultimate mismatch at a localized position in the primer. This creates differential binding affinity where the primer efficiently amplifies the native allele but shows reduced efficiency for non-native alleles with mismatched sequences. This localized modification provides reliable allele-specific amplification without requiring complex primer structures or multiple primer combinations.
Solution Approach 2:
The patent modifies the primer sequence parameter by introducing a controlled mismatch at the 3' penultimate position. This parameter change creates sufficient thermodynamic difference in binding affinity between matching and mismatching templates, ensuring that only the intended native allele is efficiently amplified while non-native alleles are suppressed, thereby achieving high specificity.
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
Enables sensitive and specific detection and quantification of donor-specific cell-free DNA, facilitating early prediction of transplant rejection and improving clinical outcomes by providing a non-invasive, cost-effective surveillance method.
Implementation Method 1
performing an amplification-based quantification assay on the sample, or portion thereof, with at least two primer pairs, wherein each primer pair comprises a forward primer and a reverse primer, wherein one of the at least two primer pairs comprises a 3' penultimate mismatch in a primer relative to one allele of the SNV target but a 3' double mismatch relative to another allele of the SNV target and specifically amplifies the one allele of the SNV target
Data Source
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AI summary
This invention relates to methods and compositions for assessing an amount of non- native nucleic acids in a sample, such as from a subject. The methods and compositions provided herein can be used to determine risk of a condition in a subject.