DNA Methylation Profiling Using Restriction Enzymes and Sequencing
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Solution Overview
Problem
Existing methods for detecting genetic and epigenetic changes in cell-free DNA from biological fluids, such as plasma and urine, are cumbersome, prone to noise, and require multiple assays, making them inefficient for early cancer detection due to low DNA concentrations and sequence alteration issues.
Innovation Solution
The use of methylation-sensitive restriction enzymes for DNA digestion followed by high-throughput sequencing, without bisulfite conversion, allows for sensitive and accurate profiling of methylation, mutation, and other epigenetic characteristics from a single run, preserving sequence information at DNA ends and enabling direct determination of methylated and unmethylated levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sodium bisulfite treatment is used to convert unmethylated cytosine to uracil, then methylation detection capability is improved, but template DNA degradation occurs and assay complexity increases
Solution Approach 1:
The invention extracts and utilizes only the methylation-sensitive property of specific restriction enzymes without employing the harmful bisulfite conversion step. By selecting enzymes like HpaII and HheCI that are sensitive to methylation at specific sites, the method achieves methylation detection while preserving DNA integrity, directly resolving the contradiction between detection capability and template integrity
Solution Approach 2:
The invention introduces methylation-sensitive restriction enzymes as intermediary tools that mediate between the DNA sample and detection. These enzymes specifically recognize and cleave unmethylated sites while leaving methylated sites intact, providing an indirect but accurate measure of methylation status without directly chemically modifying the DNA template, thus avoiding degradation
2Measurement precision
If sodium bisulfite treatment is applied, then methylation conversion is achieved, but sequence information is altered and mutation analysis is hampered
Solution Approach 1:
The invention turns the potential harm of DNA modification into a benefit by using restriction enzymes that naturally exhibit methylation sensitivity. Instead of forcing chemical conversion that destroys sequence information, the method exploits the enzymatic recognition of methylated versus unmethylated states, converting the methylation difference directly into a detectable pattern while preserving the original sequence
Solution Approach 2:
The invention creates a copy of the methylation status information through restriction enzyme digestion patterns. By digesting DNA with methylation-sensitive enzymes and analyzing the resulting fragment patterns via sequencing, the method copies the methylation information into a detectable format without altering the original DNA sequence, thereby preserving both methylation and mutation data
3Adaptability or versatility
If multiple assays are performed for genetic and epigenetic analysis, then comprehensive information is obtained, but procedure complexity and time consumption increase
Solution Approach 1:
The invention merges multiple detection capabilities into a single unified assay. By using methylation-sensitive restriction enzymes followed by high-throughput sequencing, the method simultaneously detects methylation patterns, genetic mutations, and other epigenetic characteristics in one integrated workflow, eliminating the need for separate bisulfite conversion and PCR assays
Solution Approach 2:
The invention creates a universal detection platform that can analyze multiple types of genetic and epigenetic information simultaneously. The restriction enzyme digestion followed by sequencing approach serves multiple functions: detecting methylation at restriction sites, identifying mutations in the sequence, and providing fragment length information, all from a single assay rather than requiring multiple specialized tests
4Measurement precision
If high DNA amounts are used for sequencing, then data quality is improved, but sample requirements increase and low-concentration cell-free DNA cannot be effectively analyzed
Solution Approach 1:
The invention changes the key parameter of DNA input requirement by using restriction enzyme digestion to enrich for methylated fragments before sequencing. This parameter change allows high-quality sequencing data to be obtained from very low amounts of cell-free DNA (as low as 1-10 ng), transforming the method from requiring large DNA inputs to being effective with trace amounts typical of liquid biopsy samples
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
This method provides high-quality sequencing data from low DNA amounts, enabling sensitive detection of early-stage cancer markers and comprehensive genetic and epigenetic information, with improved coverage and reduced noise, without the need for amplification or bisulfite conversion.
Implementation Method 1
subjecting the cell-free DNA sample to digestion with at least one methylation-sensitive restriction endonuclease, to obtain restriction endonuclease-treated DNA in which methylated restriction sites are intact and unmethylated restriction sites are cut
Data Source
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AI summary
Methods and systems for genetic and epigenetic profiling of DNA samples and detecting genetic and epigenetic changes in DNA samples are provided, which involve digestion of DNA with methylation-sensitive restriction enzymes, followed by high- throughput sequencing and analysis of sequence reads. Advantageously, the methods and systems of the present invention are sensitive yet accurate, and enable working with very low amounts of DNA and receive vast amount of information, including methylation data, mutation data and more, based on sequencing data from a single run.