Primer Set Design for Interspersed Element Detection
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Solution Overview
Problem
Current methods for creating multiplex PCR reactions using interspersed genetic elements are challenging due to the high frequency and sequence similarity of these elements throughout the human genome, leading to difficulties in targeting specific polymorphic marker sites and achieving uniqueness, which results in inconsistent results and preferential amplification of 'empty' site fragments over 'filled' site fragments.
Innovation Solution
A primer set design that includes a first primer for a 'filled' site containing an interspersed element, a second primer complementary to a flanking genomic sequence and a direct repeat sequence next to the element, and a third primer for an 'empty' site without the element, which is complementary to a direct repeat sequence and flanking genomic sequences on both sides, allowing for the amplification of both 'filled' and 'empty' sites in a single reaction without preferential amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional primer design methods are used for interspersed genetic elements, then the elements can be targeted, but preferential amplification of 'empty' site fragments occurs and results are inconsistent
Solution Approach 1:
The primer design incorporates locus-specific sequences flanking the interspersed element along with the direct repeat sequence, creating a unique local identifier for each insertion site. This local quality differentiation allows specific targeting of filled sites while preventing non-specific amplification of empty sites, thereby improving both reliability and measurement precision
Solution Approach 2:
The primer is divided into distinct functional segments: a locus-specific flanking sequence portion and a direct repeat sequence portion. This segmentation allows the primer to simultaneously provide location-specific targeting and element-specific binding, resolving the contradiction between general amplification capability and specific marker identification
2Adaptability or versatility
If multiplex PCR reactions are created using interspersed genetic elements, then genetic diversity can be detected, but sequence similarity of elements throughout the genome causes difficulties in targeting specific sites
Solution Approach 1:
Each primer is designed with a unique locus-specific flanking sequence that is specific to the target insertion site. This local quality ensures that even though interspersed elements have high sequence similarity throughout the genome, the primer will only bind to the intended specific site, enabling precise targeting while maintaining the ability to detect genetic diversity across multiple loci
Solution Approach 2:
The direct repeat sequence acts as an intermediary binding element that is common to all interspersed elements of a particular type, while the flanking locus-specific sequence provides the unique addressing capability. This intermediary approach allows multiplexing while maintaining site-specificity
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 design enables efficient and consistent amplification of both 'filled' and 'empty' sites, reducing the risk of false results and allowing for the identification of polymorphic markers with high specificity, thereby improving genetic testing accuracy.
Implementation Method 1
carrying out a polymerase chain reaction (PCR) on a DNA sample with a primer set to produce amplified DNA products
Data Source
AI summary
The way to design a “filled” site (which contains an interspersed element) primer set to target a particular locus is to design one of the two primers such that it encompasses that unique information (e.g., interspersed element+flanking genomic sequence+direct repeat). The way to design an “empty” site primer is to design one of the two primers such that the entire direct repeat sequence in addition to flanking genomic sequence is included on both sides. To improve efficiency, the “empty” site primer designed around the direct repeat should not be too long. This primer design of the present invention allows for the ability to test any type of interspersed genetic element containing characteristic direct repeat sequences (direct repeats). This gives the option of many new polymorphic marker sites because Alu elements are not the only interspersed genetic elements having direct repeats flanking their core sequence.