Multiplex PCR Kit Using Mini-STRs for Degraded DNA Analysis
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Solution Overview
Problem
Current STR analysis techniques struggle with degraded or denatured DNA samples, leading to incomplete genotype profiles in forensic investigations, as existing methods like GlobalFiler™ PCR amplification card and PowerPlex® fusion system fail to analyze DNA samples effectively at loci with large amplified products, limiting identity determination and database inclusion.
Innovation Solution
A multiplex PCR kit using a new mini-STR combination at 7 gene loci, including the SE33 locus, which reduces the size of amplified products to enhance sensitivity, allowing for simultaneous analysis of multiple STR alleles and sex discrimination, thereby improving the success rate of STR analysis and enabling identification even from degraded DNA samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional STR analysis methods (GlobalFiler™ PCR amplification card, PowerPlex® fusion system) are used, then standard genotype identification can be achieved, but analysis fails at loci with large amplified products when DNA is degraded or denatured
Solution Approach 1:
The patent changes the key parameter of amplified product size by developing mini-STR markers with smaller amplicon lengths (100-300 bp) compared to conventional STR markers. This parameter change enables successful amplification and analysis of degraded DNA samples where conventional methods fail, as smaller fragments are more likely to survive degradation and can be amplified even from partially denatured templates.
2Adaptability or versatility
If mini-STR markers with smaller amplified products are used, then analysis of degraded DNA samples becomes possible, but gene identification sensitivity must be maintained
Solution Approach 1:
The patent applies local quality by selecting specific genomic loci for mini-STR development that maintain high discriminatory power despite reduced amplicon size. The mini-STR markers are designed at carefully chosen locations where the repeat regions provide sufficient variability for accurate genotype identification, ensuring that local genetic characteristics are preserved even as overall fragment length is reduced.
3Reliability
If STR allele genotype analysis is performed on degraded DNA samples, then incomplete profiles are obtained at loci with large amplified products, but complete identity determination is required
Solution Approach 1:
The patent segments the STR analysis into two categories: conventional STR markers for intact DNA samples and mini-STR markers for degraded DNA samples. This segmentation allows forensic practitioners to select the appropriate marker type based on DNA quality, ensuring complete genotype profiles can be obtained regardless of sample condition. The mini-STR markers specifically target loci that would otherwise fail in degraded samples, preventing information loss.
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 multiplex PCR kit effectively discriminates mini-STRs at previously unanalyzable loci, increasing the success rate of STR analysis, enhancing identity determination, and providing reliable forensic evidence for crime scene reconstruction by enabling gene identification from degraded DNA samples.
Implementation Method 1
amplifying specific DNA sites in chromosomes (STR regions in autosomes and sex chromosomes) based on PCR
Implementation Method 2
when STR analysis is conducted through existing capillary electrophoresis (CE), STR allele genotype analysis results cannot be obtained
Data Source
AI summary
The present invention provides a multiplex PCR kit with improved STR analysis success rate by introducing mini-STRs at 7 gene loci including a mini-STR at SE33 locus, which has high gene identification sensitivity, into a human genotype profile identification technique, as well as a method for identification of human genotype profiles using the same. According to the present invention, the STR analysis success rate is improved by identifying an STR at a locus that cannot be discriminated depending on DNA degradation level, thereby offering a lot of DNA information. Further, the present invention may contribute to more efficient DNA identification such as extension of database record, increase in identity determination success rate, etc. Still further, clues for reconstruction of a crime scene may be offered while improving reliability of forensic investigation results, simultaneously, thereby contributing to solving the crime.