Forensic RNA Marker Panels for Low-Quantity Sample Identification
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Solution Overview
Problem
Traditional methods for identifying body fluids and tissue samples at crime scenes are labor-intensive, time-consuming, and expensive, and existing gene expression analysis techniques require large amounts of mRNA or miRNA, which are not readily available from small forensic samples.
Innovation Solution
The use of marker panels comprising differentially expressed genes for mRNA and miRNA, combined with PCR amplification and microarray analysis, to generate gene expression profiles that allow for the identification of forensic samples by comparing the relative concentration of RNA species in the sample to known profiles of tissues and body fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional methods are used for identifying body fluids, then identification can be achieved, but the process becomes labor-intensive, time-consuming, and expensive
Solution Approach 1:
The patent replaces traditional mechanical/manual identification methods with automated gene expression analysis using PCR amplification and microarray hybridization. This substitution automates the identification process, reducing labor intensity and time while maintaining reliability through objective molecular biomarker detection
Solution Approach 2:
The patent changes the identification approach from macroscopic physical/chemical analysis to molecular-level gene expression analysis. By detecting differential expression patterns of specific genes (such as PSAAP for prostate tissue or PRL for pituitary tissue), the method achieves rapid and reliable identification through quantitative molecular parameters
2Measurement precision
If gene expression analysis techniques are used, then identification accuracy is improved, but large amounts of mRNA or miRNA are required which are not available from small forensic samples
Solution Approach 1:
The patent performs preliminary amplification of target nucleic acid sequences using PCR before hybridization to the microarray. This preliminary action increases the quantity of detectable target molecules from limited forensic samples, enabling subsequent precise gene expression analysis that would otherwise be impossible with such small sample sizes
Solution Approach 2:
The patent introduces cDNA (complementary DNA) as an intermediary molecule. RNA samples are first reverse-transcribed into cDNA, which is then amplified and used for microarray hybridization. This intermediary approach allows the method to work with small amounts of original RNA while maintaining measurement precision through the amplification and stabilization provided by the cDNA intermediate
3Adaptability or versatility
If more nucleic acid could be obtained from crime scene samples, then gene expression analysis could be employed, but forensic samples are often small with low nucleic acid quantity
Solution Approach 1:
The patent performs preliminary amplification of target nucleic acid sequences using PCR before hybridization to the microarray. This preliminary action increases the quantity of detectable target molecules from limited forensic samples, enabling subsequent precise gene expression analysis that would otherwise be impossible with such small sample sizes
Solution Approach 2:
The patent changes the physical state and quantity parameters of the nucleic acid through amplification. By exponentially increasing the copy number of target sequences through PCR cycles, the method transforms insufficient sample quantities into adequate amounts for reliable detection, thereby expanding method applicability to small forensic samples
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 method enables efficient and cost-effective identification of forensic samples by amplifying and quantitating specific RNA markers, overcoming the limitations of low nucleic acid quantities in crime scene samples, and providing reliable results for sample source determination.
Implementation Method 1
a reverse transcriptase or a DNA-dependent DNA polymerase with reverse transcriptase activity, for example but not limited to, Tth DNA polymerase is combined with a gene-specific first primer for each target to be analyzed and a DNA complement of the RNA target is generated
Implementation Method 2
This is followed by PCR amplification using a gene-specific primer pair or a gene-specific primer and a universal primer for each marker
Implementation Method 3
mRNA and/or miRNA profiling comprises a microarray, including but not limited to a planar array and a bead-based array, wherein the relative concentration of two different species of miRNA and/or mRNA are determined using well-known hybridization-based techniques
Data Source
AI summary
Methods for identifying forensic samples using panels of markers and gene expression profiling, including without limitation, mRNA profiling, miRNA profiling, or both, are disclosed. Panels of markers for identifying certain tissue samples and certain body fluid samples are also disclosed. Kits for expediting performance of certain of the disclosed methods are provided.