Oligonucleotide Probe Design for ABL Gene Mutation Detection
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Solution Overview
Problem
Current methods for detecting point mutations in abl genes, particularly in leukemia patients, face challenges such as low sensitivity and specificity, leading to difficulties in distinguishing between mutated and normal sequences, which can result in false-negative detections and reduced diagnostic accuracy.
Innovation Solution
Development of specific oligonucleotide probes that can differentiate between mutated and normal abl gene sequences by utilizing unique base sequences and fluorescence quenching mechanisms to enhance signal separation in melting curve analysis, allowing for improved detection sensitivity and specificity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional probes are used for detecting point mutations in abl genes, then the detection method is simple, but the sensitivity is low and false-negative results occur when mutated and normal sequences coexist
Solution Approach 1:
The probe is divided into three distinct regions: a 5′ region (1-9 bases) with high affinity for mutated sequences, a middle region (10-18 bases) that binds to both mutated and normal sequences, and a 3′ region (19-25 bases) that provides additional binding stability. This segmentation allows the probe to differentiate between mutated and normal sequences by creating distinct melting temperature profiles for each target type.
Solution Approach 2:
Different regions of the probe are designed with different binding characteristics: the 5′ region is optimized for high specificity to mutated sequences with higher GC content, while the middle and 3′ regions provide general binding capability. This local optimization of binding affinity and specificity in different probe regions enables the detection to achieve high sensitivity (detecting mutations even when normal sequences are present) while maintaining a relatively simple overall probe structure.
2Measurement precision
If Tm analysis is used to detect point mutations, then the method can identify mutations, but the sensitivity decreases when normal sequences are present alongside mutated sequences
Solution Approach 1:
The probe is pre-designed with a specific base composition distribution before the detection process: the 5′ region is engineered to have higher GC content (60-80% GC) to create a higher melting temperature for mutated sequence hybrids, while the middle and 3′ regions have lower GC content (30-50%). This preliminary structural arrangement ensures that when both mutated and normal sequences are present, the mutated sequence hybrid will melt at a distinctly higher temperature, allowing reliable detection despite the presence of normal sequences.
3Measurement precision
If direct sequencing or pyrosequencing is used for mutation detection, then comprehensive sequence analysis is achieved, but the sensitivity is only approximately 5-20% and considerable time and labor are required
Solution Approach 1:
Instead of sequencing the entire amplified region, the method extracts and detects only the specific point mutation of interest using a specially designed probe. The probe's 5′ region is complementary to the mutated sequence at the specific position, allowing selective detection of the mutation without requiring comprehensive sequencing of the entire gene region. This extraction of the critical detection element from the full sequencing process achieves high sensitivity (detecting mutations even in the presence of normal sequences) while dramatically reducing the time and labor required compared to full sequencing 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
The new probes enable more accurate detection of mutated abl genes even when present with normal genes, enhancing diagnostic sensitivity and specificity, thereby improving the management of leukemia, especially in cases resistant to imatinib treatment.
Implementation Method 1
a probe complementary to a sequence to be detected containing a target point mutation is used to form a hybrid (double-stranded DNA) between the aforementioned probe and a target single-stranded DNA
Implementation Method 2
this hybridization product is heat-treated, so that dissociation (melting) of the hybrid accompanying the temperature rise is detected
Data Source
AI summary
Detection probes are provided that are capable of detecting a sequence to be detected containing a mutation even when a sequence not to be detected containing no mutation coexists with the sequence to be detected containing a mutation, which are different only in a single base from each other. At least one oligonucleotide selected from the group consisting of SEQ ID NOs: 2˜16 is used as a probe. Even in a sample containing an abl gene in which a mutation has occurred and an abl gene in which no mutation has occurred, the use of such probes in, for example, Tm analysis allows the mutation to be detected.