DNA Methylation Markers for Forensic Body Fluid Identification

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Solution Overview

Problem

Current methods for identifying body fluids at crime scenes are often presumptive, unspecific, and can destroy the sample, making them impractical for forensic analysis, especially when distinguishing between semen, saliva, and blood.

Innovation Solution

The use of DNA methylation markers specific to semen, saliva, and blood, analyzed through pyrosequencing and high-resolution melt (HRM) analysis, allows for sensitive and tissue-specific identification of body fluids, even in forensic samples, using primers and reagents designed for specific genetic loci.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If serological or immunological methods are used for body fluid identification, then detection capability is provided, but the methods are presumptive and unspecific, cannot confirm presence, and may destroy the sample

Engineering Contradiction:

Improveconfirmation accuracyVSAvoidsample destruction

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces serological/immunological detection methods with DNA-based molecular biology methods. Specifically, it uses DNA extraction followed by PCR amplification of methylation-specific markers, substituting protein-based detection with nucleic acid-based detection to achieve confirmatory results without sample destruction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent detects DNA methylation patterns at specific genomic loci as a parameter to identify body fluid sources. By analyzing methylation status (methylated vs unmethylated) at tissue-specific loci, the method provides confirmatory identification while preserving the sample for further analysis

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If serological or immunological methods are used for body fluid identification, then detection capability is provided, but the methods require large sample amounts

Engineering Contradiction:

Improvesample amount requiredVSAvoididentification accuracy

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses PCR amplification to generate sufficient DNA signal from minimal starting material. By selectively amplifying only the relevant methylation markers at specific loci, the method achieves high identification accuracy from forensic-sized samples without requiring large quantities of body fluid

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent extracts and analyzes only the specific DNA methylation markers relevant to body fluid identification from the complex mixture of forensic samples. This targeted extraction of diagnostic information from minimal sample material enables accurate identification with small sample amounts

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If DNA methylation markers are used for body fluid identification, then tissue-specific and sensitive analysis is achieved, but the method complexity increases

Engineering Contradiction:

Improvetissue-specific identification accuracyVSAvoidassay complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the DNA analysis into separate loci-specific assays, with each primer pair targeting a specific genomic locus with known tissue-specific methylation patterns. This segmentation allows systematic analysis of multiple body fluid sources through individual locus assessments

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses methylation-specific primers as intermediaries to detect DNA methylation patterns. These primers are designed to bind only to methylated or unmethylated sequences at specific loci, serving as mediators that translate epigenetic information into detectable PCR signals for body fluid identification

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach provides accurate and sensitive identification of body fluids, avoiding sample destruction and requiring minimal sample amounts, enabling precise determination of DNA sources from single or multiple sources.

Implementation Method 1

the methods disclosed herein can be used for the identification of semen containing sperms, saliva, and blood using pyrosequencing and/or high-resolution melt (HRM) analysis

Methodology Applied

Scientific EffectPyrosequencing:

Implementation Method 2

the methods disclosed herein can be used for the identification of semen containing sperms, saliva, and blood using pyrosequencing and/or high-resolution melt (HRM) analysis

Methodology Applied

Scientific EffectHigh-resolution melt analysis:

Data Source

PatentUS10907203B1DNA methylation assays for body fluid identification

Publication Date: 2021.02.02 FLORIDA INTERNATIONAL UNIVERSITY

AI summary

The invention pertains to analyzing the DNA methylation levels at specific genetic loci. The DNA methylation levels at the specific genetic loci can be used to detect the presence in a sample of a specific body fluid, for example, semen containing sperm, saliva, or blood. Particularly, the DNA methylation levels at the genetic loci corresponding to SEQ ID NOs: 1, 7, 13, and 19 are used to detect sperms, saliva or blood cells. The DNA methylation levels at the specific loci can be determined by high-resolution melt (HRM) analysis or sequencing of the amplicons produced using specific primers designed to amplify the specific loci. Kits containing the primers and reagents for carrying out the methods disclosed herein are also provided.