FFPET DNA Isolation Using Q-Ratio Quality-Mass Constant
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Solution Overview
Problem
The process of genotyping tumor tissues from formalin-fixed paraffin-embedded (FFPET) samples is hindered by DNA damage, leading to inefficient and variable DNA isolation, which complicates accurate variant detection due to increased noise and decreased signal quality.
Innovation Solution
A method involving the isolation and quantification of DNA using qPCR-based assays to determine the quality-mass constant (kQm) and Q-ratio, ensuring sufficient DNA input for sequencing, along with uracil N-glycosylase treatment and DNA fragmentation, to enhance DNA quality and quantity for next-generation sequencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard molecular biology techniques are used to process FFPET-derived DNA, then the processing can be performed with conventional methods, but the efficiency is decreased due to chemical damage from fixation and embedding
Solution Approach 1:
The patent modifies standard molecular biology protocols by adjusting parameters such as DNA extraction conditions, amplification cycles, and sequencing library preparation steps to accommodate damaged FFPET DNA, thereby maintaining ease of processing while improving efficiency
Solution Approach 2:
The patent performs preliminary damage assessment and repair steps before main processing, including pre-extraction evaluation of DNA quality and preliminary repair of formalin-induced damage, to prevent downstream processing failures
2Duration of action of stationary object
If FFPET samples are stored for long periods, then sample availability is improved for retrospective studies, but chemical damage to DNA increases making variant identification more difficult
Solution Approach 1:
The patent converts the harmful effects of long-term storage and chemical damage into beneficial information by using the damage pattern itself as a diagnostic feature and by developing computational methods that specifically account for and correct storage-induced artifacts
Solution Approach 2:
The patent introduces intermediary steps including DNA repair enzymes, protective chemicals, and computational correction algorithms that mediate between the damaged historical sample and the modern sequencing technology
3Device complexity
If DNA isolation is performed using conventional methods, then the process is simpler, but the quantity and quality of isolated DNA are highly variable
Solution Approach 1:
The patent implements feedback mechanisms where DNA quality and quantity are measured at intermediate steps, and subsequent processing parameters are adjusted based on these measurements to ensure consistent output
Solution Approach 2:
The patent divides the DNA isolation process into multiple controlled stages with quality checkpoints, allowing optimization of each step independently while maintaining overall process simplicity
4Productivity
If standard sequencing is performed on damaged DNA, then the workflow remains straightforward, but the signal-to-noise ratio decreases making variant detection less confident
Solution Approach 1:
The patent performs preliminary damage repair and enrichment of intact DNA fragments before sequencing, removing damaged portions that would generate noise signals during sequencing
Solution Approach 2:
The patent applies different processing strategies to different regions of the genome, focusing intensive repair and enrichment on regions of high clinical interest while using standard processing for other areas
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 approach enables more confident and efficient variant detection at a lower limit of detection by improving DNA quality and quantity, reducing error rates, and maximizing signal-to-noise ratios in sequencing.
Implementation Method 1
quantifying a first quantification cycle (Cq) of the first target region and a second Cq of the second target region in the composition
Data Source
AI summary
Present disclosure provides a method including isolating DNA from a source, thereby providing a composition including the isolated DNA. The isolated DNA has at least first and second target regions, where the length of the second target region is greater than the length of the first target region. The method further includes quantifying a total mass of the isolated DNA, quantifying a first quantification cycle (Cq) of the first target region and a second Cq of the second target region, and calculating a Q-ratio for the isolated DNA by dividing the second Cq by the first Cq. The method further includes determining a value for a quality-mass constant (kQm), estimating a required input mass by dividing kQm by the Q-ratio, and preparing the isolated DNA for sequencing if the total mass of the isolated DNA in the composition is equal or greater than the required input mass.