CALR Mutation Detection via Fragment Length Analysis
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Solution Overview
Problem
Current diagnostic methods for myeloproliferative neoplasms (MPNs) face challenges in distinguishing essential thrombocythemia without JAK2 mutations from reactive thrombocytosis and in accurately detecting calreticulin (CALR) mutations, which are difficult with conventional sequencing techniques, and require invasive tumor sampling for disease monitoring.
Innovation Solution
The method involves extracting cell-free DNA from peripheral blood plasma or serum for fragment length analysis (FLA) of the CALR gene, combined with bidirectional sequencing, using specific primers to quantify allele burden and determine tumor load, allowing non-invasive monitoring and differentiation of MPNs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sequencing techniques are used to detect CALR mutations, then the diagnostic process is simple and familiar, but the detection sensitivity and accuracy are insufficient for indel mutations
Solution Approach 1:
The patent changes the detection parameter from sequence composition (conventional sequencing) to fragment length (FLA). By amplifying the CALR exon 9 region and measuring the length of amplified fragments, the method can detect indel mutations with high sensitivity. The fragment length directly reflects the presence of insertions or deletions, providing accurate detection without complex sequencing analysis.
Solution Approach 2:
The patent replaces the complex mechanical/electrical system of conventional sequencing with a simpler fragment length analysis approach. Instead of using sequencing machines to read nucleotide sequences, the method uses PCR amplification followed by fragment length measurement (e.g., via capillary electrophoresis), which is simpler and more suitable for detecting indel mutations in clinical settings.
2Measurement precision
If invasive tumor sampling is performed for disease monitoring, then accurate tumor information can be obtained, but patient discomfort and procedural complexity increase
Solution Approach 1:
The patent uses cell-free DNA in plasma as an intermediary to obtain tumor information without directly sampling tumor tissue. The cell-free DNA circulates in the blood and contains genetic information from the tumor, serving as a non-invasive proxy for tumor analysis. This allows accurate tumor load measurement through simple blood draws rather than invasive biopsies.
Solution Approach 2:
The patent extracts and analyzes cell-free DNA from plasma as a separate, non-invasive source of tumor information. Instead of extracting DNA from invasive tumor samples, the method isolates circulating cell-free DNA that originates from tumor cells, enabling disease monitoring through routine blood collection rather than painful procedures.
3Productivity
If JAK2 mutation testing is performed alone, then the diagnostic process is straightforward, but essential thrombocythemia cases without JAK2 mutations cannot be distinguished from reactive thrombocytosis
Solution Approach 1:
The patent makes the diagnostic approach universal by developing a method that works for both JAK2-mutated and JAK2-wild type cases. The fragment length analysis of CALR exon 9 provides a single diagnostic tool that can identify mutations across different MPN subtypes, eliminating the need for separate diagnostic pathways and improving both efficiency and accuracy.
Solution Approach 2:
The patent performs preliminary CALR fragment length analysis on all suspected MPN cases before making a diagnosis. This preliminary screening using FLA ensures that both JAK2-mutated and JAK2-wild type cases are accurately identified, preventing misdiagnosis of reactive thrombocytosis as essential thrombocythemia in JAK2-negative patients.
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 a sensitive and accurate method for detecting CALR mutations and determining tumor load, improving diagnosis and monitoring of MPNs, particularly in cases without JAK2 or MPL mutations, and offering prognostic insights through biallelic mutation detection.
Implementation Method 1
separating the labeled fragments by size using capillary electrophoresis
Data Source
AI summary
Compositions and fragment length analysis methods are provided for detecting CALR mutations and determining tumor load in patients with myeloproliferative neoplasms.