High-Tm PCR Amplification for MRD in Rearranged Ig/TCR Genes
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Solution Overview
Problem
Current PCR-based methods for detecting and quantifying minimal residual disease (MRD) in lymphoid cancers suffer from nonspecific amplification, leading to false positives and limited sensitivity, making it difficult to detect MRD below 10 -4< , especially in conditions like acute lymphoblastic leukemia and chronic lymphocytic leukemia.
Innovation Solution
A highly sensitive one-round PCR method using primers with a Tm of at least 67°C and an annealing temperature of at least 70°C, designed to hybridize to at least two N regions of rearranged Ig or TCR genes, significantly reducing non-specific amplification and enabling detection of MRD down to 10 -6< .
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR methods are used with standard primers and annealing temperatures, then the amplification process is simple and fast, but the sensitivity is limited and nonspecific amplification occurs, making it impossible to detect MRD below 10^-4
Solution Approach 1:
The patent applies parameter changes by optimizing primer Tm to at least 67°C and annealing temperature to at least 70°C, which fundamentally changes the thermal parameters of the PCR process. This resolves the contradiction by enabling detection sensitivity down to 10^-6 while maintaining a relatively simple one-round PCR protocol without requiring complex nested or multiplex approaches
2Reliability
If standard primers with lower Tm are used, then the PCR reaction proceeds efficiently at lower annealing temperatures, but nonspecific amplification increases leading to false positives
Solution Approach 1:
The patent changes the temperature parameter by setting the annealing temperature to at least 70°C, which is sufficiently high to prevent nonspecific binding while still allowing efficient amplification. This resolves the contradiction between reliability (specificity) and temperature by demonstrating that high annealing temperatures can achieve both specificity and efficiency when combined with appropriately designed high-Tm primers
3Measurement precision
If primers with Tm of at least 67°C and annealing temperature of at least 70°C are used, then detection sensitivity improves to 10^-6, but the risk of primer-dimer formation and amplification failure increases
Solution Approach 1:
The patent applies local quality by designing primers with specific local characteristics: Tm of at least 67°C, inclusion of A/T nucleotides at the 3' end, and hybridization to at least two N regions. These localized modifications to primer structure ensure high sensitivity detection while maintaining amplification efficiency by preventing primer-dimer formation and ensuring specific binding to the target sequence
4Measurement precision
If complex multiplex or nested PCR reactions are used, then detection sensitivity can be improved, but the procedure becomes more complex and expensive
Solution Approach 1:
The patent extracts and eliminates the need for complex multiplex or nested PCR procedures by using a simplified one-round PCR approach with optimized primers and temperature conditions. This resolves the contradiction by achieving high detection sensitivity (10^-6) through a single, simple amplification reaction rather than requiring multiple complex steps
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 method provides reproducible and sensitive detection and quantification of MRD, allowing for improved monitoring of clonal lymphoid cell populations, particularly in lymphoid neoplasias, without the need for complex multiplex or nested PCR reactions or expensive next-gen sequencing.
Implementation Method 1
both the forward primer and the reverse primer have a Tm of at least 67°C... amplifying said nucleic acid sample using an annealing temperature of at least 70°C
Data Source
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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 using primers which exhibit a high Tm and/or using a high annealing temperature enables higher levels of sensitivity than has previously been achievable in the context of prior art methods of amplifying rearranged immunological or T cell receptor genes. Still further improvements in sensitivity are achievable where the subject primer hybridises to at least two N regions of the recombined gene. 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.