Whole Genome Amplification Using Phi29 Polymerase
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current whole genome amplification methods introduce artifacts and errors, especially when starting with limited DNA or RNA samples, making it difficult to detect rare mutations due to issues like allele dropout and template-independent DNA amplification (TIDA).
Innovation Solution
The use of phi29 polymerase and a heat-stable DNA polymerase with specific primer designs for whole genome amplification (WGA) and next-generation sequencing (NGS) that eliminates sample clean-up steps, reduces TIDA, and allows for high-fidelity amplification of nucleic acids from limited samples, such as single cells, with optional enrichment for specific targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing whole genome amplification methods are used to amplify limited DNA samples, then amplification is achieved, but artifacts and errors are introduced making it difficult to detect rare mutations
Solution Approach 1:
The patent employs multiple displacement amplification (MDA) using phi29 polymerase with optimized reaction conditions (pH 8.8, 12 mM Tris, 60 mM KCl, 2 mM MgCl2, 100 µg/mL BSA, 1.5 mM dNTPs) to achieve high-fidelity amplification. The reaction is conducted at 30°C for 8-16 hours to minimize errors and artifacts while maximizing amplification of limited DNA samples
Solution Approach 2:
The patent introduces an intermediary purification step using magnetic beads to remove amplification artifacts and contaminants before sequencing. This intermediate purification step eliminates harmful factors while preserving the amplified DNA for accurate mutation detection
2Quantity of substance
If conventional WGA methods are used on single cells, then genome amplification is achieved, but template-independent DNA amplification (TIDA) occurs reducing fidelity
Solution Approach 1:
The patent optimizes reaction parameters including pH 8.8, temperature 30°C, and extended incubation time (8-16 hours) to maximize template-dependent amplification while minimizing template-independent amplification. The use of phi29 polymerase with proofreading activity further ensures high fidelity amplification from single cell DNA
Solution Approach 2:
Magnetic bead purification serves as an intermediary step that selectively removes TIDA products and other artifacts while retaining authentic amplified DNA, thereby restoring and maintaining amplification fidelity
3Productivity
If existing WGA methods are used with limited samples, then amplification is achieved, but sample clean-up steps are required increasing complexity
Solution Approach 1:
The patent combines the amplification and purification steps into a streamlined workflow where magnetic bead-based cleanup is integrated directly after the MDA reaction. This merging of steps eliminates intermediate transfers and reduces overall processing complexity while maintaining high amplification efficiency
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 provides accurate and efficient detection of nucleic acid variants by minimizing errors and artifacts, achieving high polymerase processivity and coverage with reduced chimera and allele dropout, enabling robust amplification and sequencing of single cell samples with improved fidelity and scalability.
Implementation Method 1
contacting a sample of genomic DNA with a phi29 polymerase and a heat stable DNA polymerase; and amplifying the genomic DNA to generate amplified DNA
Data Source
AI summary
Provided herein are systems and methods for whole genome amplification and sequencing. In particular, provided herein are systems and methods for detection of nucleic acid variants (e.g., rare variants) in limited samples.