PCR Primer Annealing for Sensitive MRD Gene Rearrangement Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current PCR-based methods for detecting minimal residual disease (MRD) in lymphoid cancers suffer from nonspecific amplification, limiting sensitivity to below 10^-4, leading to false positives and poor quantification precision, especially when MRD levels are close to the detection limit.
Innovation Solution
A PCR method using annealing temperatures within 3°C below the critical annealing temperature (Tc) and incorporating primers with A or T nucleotides at the 3' terminal position, optionally combined with melting curve analysis, to enhance sensitivity and specificity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR-based methods are used for detecting minimal residual disease, then the detection process is relatively simple, but the sensitivity is limited to below 10^-4 due to nonspecific amplification
Solution Approach 1:
The patent applies parameter changes by optimizing the annealing temperature to be 3°C below the critical annealing temperature (Tc-3°C) and modifying primer sequences to include A or T nucleotides at the 3' terminal position. These parameter changes resolve the contradiction by enhancing detection sensitivity to 10^-6 while suppressing nonspecific amplification, as the optimized parameters create more stringent conditions that favor specific binding over nonspecific binding.
Solution Approach 2:
The patent implements dynamics by introducing melting curve analysis as an additional dynamic step in the PCR process. The melting curve analysis dynamically distinguishes specific from nonspecific amplification products by monitoring the dissociation behavior of DNA duplexes at different temperatures. This dynamic approach enables the system to maintain high sensitivity while automatically filtering out nonspecific amplification artifacts.
2Measurement precision
If nested PCR or next-gen sequencing is used to improve sensitivity, then detection sensitivity increases, but the process complexity increases significantly
Solution Approach 1:
The patent resolves this contradiction by applying parameter changes to the standard PCR protocol - specifically setting the annealing temperature to Tc-3°C and designing primers with A/T at the 3' end. These modified parameters enable a single-round PCR to achieve sensitivity comparable to or exceeding nested PCR and next-gen sequencing, thereby eliminating the need for complex multi-step procedures while maintaining high detection sensitivity.
Solution Approach 2:
The patent incorporates feedback through melting curve analysis, which provides real-time information about the specificity of amplification products. The melting curve data feeds back into the interpretation of PCR results, allowing specific amplification products to be distinguished from nonspecific ones. This feedback mechanism enables a simple single-round PCR to achieve the sensitivity of complex methods by dynamically verifying amplification specificity.
3Reliability
If annealing temperature is optimized to reduce nonsspecific amplification, then specificity improves, but amplification efficiency may decrease
Solution Approach 1:
The patent applies parameter changes by identifying and implementing the optimal annealing temperature (Tc-3°C) that balances specificity and efficiency. Additionally, the primer modification (adding A/T at the 3' end) is a parameter change that enhances specificity without significantly compromising efficiency, as these nucleotides are chemically similar and maintain stable binding. The combination of these parameter changes resolves the contradiction by achieving both high specificity and maintained amplification efficiency.
Solution Approach 2:
The patent applies preliminary action by determining the critical annealing temperature (Tc) through preliminary experiments before conducting the actual diagnostic PCR. This preliminary characterization of the primer-template interaction allows the selection of an optimal annealing temperature (Tc-3°C) that预先 ensures both high specificity and efficient amplification, resolving the contradiction before the main amplification process begins.
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 detection and quantification of MRD down to 10^-6 levels with reduced non-specific amplification, simplifying the process and eliminating the need for complex nested PCR or next-gen sequencing.
Implementation Method 1
amplifying by PCR an Ig or TCR nucleic acid region
Implementation Method 2
an annealing temperature within the range between Tc and (Tc- 3°C) of the subject amplification reaction
Implementation Method 3
amplifying by PCR an Ig or TCR nucleic acid region
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates generally to an improved method of amplifying a nucleic acid region of interest and to primers for use therein. More particularly, the present invention is directed to an improved method of amplifying a nucleic acid region which has resulted from the recombination of two or more immunoglobulin or T cell receptor gene segments and primers for use therein. The method of the present invention is based on the determination that performing the amplification step at an annealing temperature determined relative to the critical annealing temperature unique to a given reaction and/or using optimised primers enables higher levels of sensitivity than have previously been achievable in the context of prior art methods of amplifying rearranged immunological or T cell receptor genes. The method of the present invention is particularly useful where the subject recombination target comprises only one N region. The provision of a highly sensitive yet simple means of detecting specific immunological and T cell receptor nucleic acid recombination events is useful in a range of applications including, but not limited to, the diagnosis and/or monitoring of clonal lymphoid cell populations or disease conditions which are characterised by specific V/D/J recombination events (such as detecting minimal residual disease in leukaemias) or the analysis or identification of immunological or T cell receptor gene regions of interest.