MLH1 Methylation Assay for Reproducible FFPE Cancer Testing
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Solution Overview
Problem
Current methods for detecting methylation of cancer-related genes, particularly in formalin-fixed paraffin-embedded (FFPE) tissues, are labor-intensive, unsuitable for multiplex analysis, and suffer from reproducibility issues due to sensitivity to inhibitors and operator variability, making it difficult to accurately assess methylation status in large numbers of samples.
Innovation Solution
A method using a combination of methylation-sensitive and methylation-insensitive restriction enzymes, along with specific probes and primers, to detect methylation of the MLH1 promoter region, allowing for robust analysis of FFPE samples by forming hybridization complexes and amplifying target nucleic acids to determine methylation status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methylation detection methods (MSP, COBRA, Methylight) are used, then methylation status can be detected, but the methods are labor-intensive and allow study of only one gene at a time
Solution Approach 1:
The patent combines multiple methylation detection capabilities into a single multiplex assay that can analyze multiple genes simultaneously. The method integrates multiple primer sets and probes targeting different genes (including MLH1, MSH2, MSH6, PMS2, and other cancer-related genes) into one reaction system, enabling parallel detection of methylation status across multiple genes without requiring separate experiments for each gene.
Solution Approach 2:
The invention creates a universal methylation detection platform that can simultaneously detect methylation of multiple different genes using a single assay system. The method employs universal detection mechanisms (fluorescent probes and PCR amplification) that work across different target genes, making the system multi-functional and applicable to various cancer-related genes in one experiment.
2Measurement precision
If current methylation detection methods are applied to FFPE tissues, then methylation analysis is possible, but reproducibility is poor due to sensitivity to inhibitors and operator variability
Solution Approach 1:
The patent optimizes reaction parameters including primer concentrations, probe concentrations, buffer composition, and thermal cycling conditions to enhance robustness against inhibitors present in FFPE samples. The method uses carefully designed reaction conditions that maintain consistent performance across different sample qualities and operator techniques, reducing variability and improving reproducibility.
Solution Approach 2:
The invention incorporates internal controls and reference genes (such as ACTB or GAPDH) that provide feedback on reaction efficiency and sample quality. By monitoring these reference targets alongside the cancer-related genes, the method can detect and compensate for variations in DNA quality, inhibitor presence, and operator technique, thereby improving reproducibility.
3Quantity of substance
If large numbers of FFPE tissue samples are analyzed, then comprehensive methylation studies are possible, but the labor-intensive nature of current methods makes this impractical
Solution Approach 1:
The patent merges multiple detection functions into a single multiplex PCR reaction that can analyze multiple genes simultaneously. This consolidation reduces the number of separate experiments needed for each sample, thereby decreasing the time and labor required per sample while enabling analysis of larger sample cohorts.
Solution Approach 2:
The method uses a closed-tube real-time PCR system that creates a controlled reaction environment, minimizing contamination risks and reducing the need for extensive post-PCR processing. This streamlined approach accelerates the workflow and reduces manual handling time, making large-scale sample analysis more feasible.
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 a cost-effective, less labor-intensive, and highly sensitive assay for detecting MLH1 promoter methylation, improving reproducibility and accuracy in FFPE samples, enabling the exclusion of Lynch syndrome as a diagnosis in colorectal and endometrial cancers.
Implementation Method 1
the methylation-sensitive restriction enzyme cleaves the double-stranded genomic DNA at unmethylated recognition sites for the methylation-sensitive restriction enzyme, leaving methylated recognition sites for the methylation-sensitive restriction enzyme intact
Implementation Method 2
the methylation-insensitive restriction enzyme cleaves the double-stranded genomic DNA at both methylated and unmethylated recognition sites for the methylation-insensitive restriction enzyme
Implementation Method 3
hybridizing the plurality of probes to the plurality of target nucleic acids in the sample to form a plurality of hybridization complexes
Implementation Method 4
amplifying the plurality of hybridization complexes to produce a plurality of amplicons
Data Source
AI summary
The present technology relates to methods for excluding Lynch syndrome as a possible diagnosis in patients suffering from colorectal cancers or endometrial cancers. These methods are based on detecting the methylation status of the MLH1 promoter ‘C’ region in colorectal and endometrial cancer patients using an improved and highly sensitive methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay.