Digital PCR Genotoxicity Assessment for Gene Editing Integrity
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Solution Overview
Problem
Current methods for evaluating targeted genetic modifications, such as those using designer nucleases, fail to accurately detect large deletions or mutations at off-target sites and underestimate or overestimate the safety and efficacy of such modifications, particularly in gene therapy applications, lacking a standardized and unbiased technique for assessing chromosomal aberrations and therapeutic transgene integration.
Innovation Solution
A method named MEGA (Multipurpose Editing Genotoxicity Assessment) using digital PCR (dPCR) with specific primer pairs and labeled probes to analyze mutation events, including flanking, on-target, loss of heterozygosity, and knock-in/off-target integration, providing a comprehensive and rapid overview of genetic integrity and chromosomal aberrations post-treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital PCR with multiple primer pairs and labeled probes is used to comprehensively detect mutation events, then measurement precision and reliability are improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent segments the detection process into multiple independent dPCR assays, each targeting specific mutation event types (flanking deletions, on-target indels, LOH, knock-in integration). Each assay uses dedicated primer pairs and labeled probes, allowing comprehensive detection while maintaining manageable complexity through modular organization of detection components
Solution Approach 2:
The patent employs a universal dPCR platform that can perform multiple detection functions using the same core technology. Different primer pairs and labeled probes are designed to target various mutation types, but all assays run on the same dPCR system, providing multi-functionality without requiring separate complex devices for each detection type
2Measurement precision
If comprehensive mutation event determination is performed on targeted chromosome, then measurement precision is improved, but loss of time increases due to multiple analyses
Solution Approach 1:
The patent merges multiple detection functions into a single integrated genotoxicity assessment workflow. All four types of mutation events (flanking deletions, on-target indels, LOH, knock-in integration) are detected through coordinated dPCR assays that can be performed in parallel or sequence, providing comprehensive evaluation in one unified process rather than separate analyses
Solution Approach 2:
The patent performs preliminary design of specific primer pairs and labeled probes for each mutation type before sample analysis. This preparatory work enables rapid execution of comprehensive detection during the actual genotoxicity assessment, as all detection components are pre-optimized and ready for simultaneous or sequential deployment without time-consuming setup during sample processing
3Measurement precision
If flanking analysis with dPCR is used to detect large deletions, then measurement precision is improved, but ease of operation deteriorates due to specialized assay requirements
Solution Approach 1:
The patent uses specifically designed flanking primer pairs as intermediaries that bind to regions adjacent to the target cleavage site. These intermediary primers enable detection of large deletions by amplifying flanking regions that remain intact even when central target sequences are deleted, providing indirect but reliable detection of deletion events through mediator sequences
4Measurement precision
If on-target analysis with dPCR is used to detect indels, then measurement precision is improved, but loss of time increases due to additional analysis steps
Solution Approach 1:
The patent employs labeled probes with different fluorescent labels (e.g., FAM, HEX, Cy3) that emit different colors when bound to target sequences. This color-based detection allows simultaneous or sequential monitoring of multiple indel events through fluorescent signal detection, providing precise quantification while enabling parallel analysis that reduces overall assessment time compared to sequential non-fluorescent methods
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
MEGA offers a quick, unbiased, and high-throughput method to quantify double-strand breaks, large deletions, and chromosomal aberrations, ensuring accurate assessment of genetic modifications in therapeutically relevant cells, enhancing the safety and efficacy of gene editing technologies.
Implementation Method 1
a first labelled probe arranged to hybridise with and assay the level of the amplified first region of DNA and a second labelled probe arranged to hybridise with and assay the level of the amplified second region of DNA
Implementation Method 2
the labels of the first and second labelled probes are different to each other, wherein the relative quantity of dPCR droplets having combined first and second labelled probe detections
Data Source
Figure 1A~1C
Figure 2A~2E
Figure 3A~3E
AI summary
The invention relates to a method for determining the level and type of mutation events associated with the use of a targeted genetic modification, such as in the use of designer nucleases, to modify a target site of nucleic acid in a cell or virus population. The method comprises carrying out a mutation event determination on a targeted nucleic acid in a population of modified nucleic acids that have been treated with the targeted genetic modification, and a reference control analysis on a non-targeted nucleic acid. The invention further relates to the use of the method for screening of potential targeted genetic modification agents for therapeutic use and to estimate the genomic integrity and stability of a nucleic acid such as a viral vector or genomic DNA.