STR Analysis Kits Using QS and QL Primers for Low-DNA Profiling
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Solution Overview
Problem
Rapid DNA testing faces challenges with noisy results due to stochastic effects, low DNA amounts, DNA degradation, and inhibited amplification, which can be exacerbated by mixed samples and environmental debris, leading to ambiguous profiles and reduced sensitivity, especially in low DNA samples.
Innovation Solution
Incorporation of quantification standards (QS and QL) and internal quality controls (IQCS and IQCL) to bracket STR regions, using primers that target specific sequences, and optimizing sample collection and PCR cycles to improve DNA quantitation and reduce stochastic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peak height thresholds are increased to eliminate artifacts from stochastic effects, then reliability of DNA profile improves, but sensitivity decreases and real alleles below threshold are missed
Solution Approach 1:
The patent introduces quantification standards (QS and QL) as intermediary elements that mediate between the stochastic amplification process and the final profile interpretation. These standards provide reference peaks of known intensity that serve as a benchmark for evaluating whether sample peaks represent true alleles or stochastic artifacts, enabling more accurate threshold determination without arbitrarily discarding low-intensity genuine alleles
Solution Approach 2:
The patent implements feedback by using the intensities of quantification standard peaks to inform the interpretation of sample peaks. The system compares sample peak intensities against the established quantification standard intensities, allowing dynamic adjustment of interpretation criteria based on the actual performance of the amplification reaction in each sample, thereby improving both reliability and sensitivity
2Productivity
If rapid DNA testing is performed with limited processing steps and human intervention, then productivity increases and results are obtained quickly, but measurement precision decreases due to noisy results from low DNA amounts and stochastic effects
Solution Approach 1:
The patent applies preliminary action by incorporating quantification standards into the amplification reaction before the actual STR loci are amplified. This allows the system to预先 establish reference intensity levels that will be used to interpret sample peaks, enabling accurate profile generation even with rapid, automated processing and minimal human intervention
Solution Approach 2:
The quantification standards serve as intermediary elements that bridge the gap between rapid automated processing and accurate profile interpretation. By providing known reference peaks early in the process, they enable the system to compensate for stochastic effects and low DNA amounts without requiring additional manual analysis steps
3Measurement precision
If quantification standards with different amplicon lengths are used to assess DNA degradation, then measurement precision improves, but device complexity increases due to additional primers and analysis steps
Solution Approach 1:
The patent applies universality by designing quantification standards that serve multiple functions: they quantify total DNA amount, assess DNA degradation state, and provide intensity references for allele interpretation. The same QS and QL primers and amplicons are used for all these purposes simultaneously, avoiding the need for separate assessment systems and reducing overall kit complexity
Solution Approach 2:
The patent merges the functions of DNA quantitation, degradation assessment, and profile interpretation by using the quantification standards for all three purposes. Instead of separate controls for each function, the system combines these requirements into a single integrated approach using QS and QL amplicons with different lengths that bracket the STR regions
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
Enhances DNA profile accuracy and sensitivity by quantifying DNA levels and identifying degradation or inhibition, allowing for reliable analysis even in low DNA samples, reducing artifacts, and maintaining rapid processing times.
Implementation Method 1
multiplex PCR amplification of STR markers
Implementation Method 2
electrophoresis to separate DNA within a sample based on size
Implementation Method 3
capillary electrophoresis applications in which nucleic acid samples are labelled with dyes, size-separated
Data Source
Figure 1A~1B
Figure 2A
Figure 2A
AI summary
Disclosed are compositions, kits, and methods for use in applications involving electrophoretic separation of nucleic acids, including capillary electrophoresis applications in which nucleic acid samples are labelled with dyes, size-separated, and subjected to short tandem repeat (STR) analysis. A sample containing DNA is mixed with a composition that includes at least one set of primers that target an STR region of the sample nucleic acid, a set of short quantification primers (QS primers) that target a first multi-copy sequence (QS sequence) of the sample nucleic acid, and a set of long quantification primers (QL primers) that target a second multi-copy sequence (QL sequence) of the sample nucleic acid, wherein the QS sequence is shorter than the QL sequence.