Trinucleotide Repeat Screening via DNA Melt Curve Analysis
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Solution Overview
Problem
Current methods for diagnosing Fragile X syndrome (FXS) are time-consuming and costly due to the need for combination of PCR and Southern blot analysis, and existing PCR-based approaches struggle with large expansions and methylation state analysis, particularly in females.
Innovation Solution
A method using specific primers and DNA melt curve analysis to screen for trinucleotide repeat expansions in the FMR1 gene, allowing for rapid and reliable differentiation of normal, premutation, and full mutation alleles in both males and females without requiring Southern blot validation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PCR and Southern blot analysis are combined for diagnosing Fragile X syndrome, then diagnostic accuracy is improved, but diagnostic time and cost increase
Solution Approach 1:
The patent combines PCR amplification with DNA melt curve analysis in a single integrated assay. The method uses fluorescently labeled primers that anneal to the FMR1 gene region, and the resulting PCR products are analyzed by melt curve analysis to detect trinucleotide repeat expansions. This merging of functions allows accurate diagnosis of Fragile X syndrome without requiring separate Southern blot analysis, thereby reducing diagnostic time and cost while maintaining accuracy.
2Ease of operation
If conventional PCR-based approaches are used for screening, then simplicity is improved, but ability to detect large expansions and methylation states deteriorates
Solution Approach 1:
The patent utilizes DNA melt curve analysis which measures the melting temperature (Tm) of PCR amplification products. The Tm value is directly related to the length of the trinucleotide repeat expansion - larger expansions produce lower Tm values. This parameter change approach allows the simple PCR-based system to reliably detect large expansions and differentiate between normal, premutation, and full mutation alleles based on their characteristic melt curves, thereby maintaining simplicity while improving detection capability.
3Productivity
If rapid screening is implemented within 24 hours, then productivity is improved, but complexity of the screening method increases
Solution Approach 1:
The patent replaces complex Southern blot analysis with a simplified PCR-based melt curve analysis system. The method uses real-time PCR with fluorescent detection and automated melt curve analysis, which can be performed within 24 hours. The complexity is managed through automated data analysis algorithms that interpret melt curve patterns to identify trinucleotide repeat expansions, thereby achieving rapid screening without requiring manual interpretation of complex gel electrophoresis results.
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
Enables accurate and efficient screening within 24 hours, distinguishing large premutation alleles from full mutations in both sexes, and identifying mosaic females, reducing diagnostic costs and time.
Implementation Method 1
a first primer, wherein said first primer has a target sequence in a region 3′ or 5′ of a trinucleotide repeat sequence in the nucleic acid sequence; ii) a second primer, wherein said second primer has a target sequence within the trinucleotide repeat sequence
Implementation Method 2
contacting a nucleic acid sequence obtained or derived from the biological sample under amplification conditions to generate an amplified product comprising a trinucleotide repeat sequence
Implementation Method 3
A method using specific primers and DNA melt curve analysis to screen for trinucleotide repeat expansions in the FMR1 gene
Data Source
AI summary
A method for screening for a trinucleotide repeat sequence in a biological sample is provided. The method comprises the step of contacting a nucleic acid sequence obtained or derived from the biological sample under amplification conditions with i) a first primer having a target sequence in a region 3′ or 5′ of a trinucleotide repeat sequence; ii) a second primer having a target sequence within the trinucleotide repeat sequence and a unique 5′ tail sequence; and iii) a third primer, having a target within the unique 5′ tail sequence of the second primer to generate an amplified product comprising a trinucleotide repeat sequence. Primers, kits of primers together with the use of the primers in methods of screening are also provided.