Amelogenin SNP Primer Design for Allelic Dropout
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Solution Overview
Problem
Current DNA-based technologies for gender determination and genotyping face challenges in accurately distinguishing between the X and Y chromosomes due to allelic dropout caused by single nucleotide polymorphisms, particularly at the amelogenin locus, which affects the sensitivity and specificity of DNA analysis.
Innovation Solution
A method involving the use of specific primers that bind to a single nucleotide polymorphism (SNP) at position 83 of the amelogenin gene on the X chromosome, with the inclusion of a universal base to prevent allelic dropout, allowing for the differentiation between X and Y chromosome amplification products through PCR, and the use of fluorescent labels for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard PCR amplification is used to determine gender, then the process is simple and quick, but allelic dropout occurs due to SNPs causing inaccurate results
Solution Approach 1:
The patent applies preliminary action by designing primers with universal bases incorporated before the PCR reaction begins. This pre-designed primer structure anticipates and prevents allelic dropout caused by SNPs at known positions, ensuring that the amplification will succeed regardless of which allele is present in the sample.
Solution Approach 2:
The universal base in the primer acts as an intermediary element that bridges the gap between the primer and the variable SNP site. This intermediary base (such as inosine or other universal nucleotides) can pair with multiple different bases, allowing the primer to bind successfully to both alleles despite sequence variations, thereby preventing amplification failure.
2Productivity
If primers are designed to be highly specific to a particular allele, then amplification efficiency is high, but allelic dropout occurs when SNP variants are present
Solution Approach 1:
The patent applies universality by designing primers that can function with multiple different target sequences. The universal base in the primer allows it to bind to multiple different alleles at the SNP site, making the primer multi-functional rather than allele-specific. This ensures that both alleles can be amplified with the same primer, preventing allelic dropout while maintaining amplification efficiency.
Solution Approach 2:
The patent changes the chemical parameter of the primer by incorporating universal bases (such as inosine, xanthosine, or other non-canonical nucleotides) that have different base-pairing properties than standard nucleotides. This parameter change allows the primer to tolerate sequence variations at the SNP position while still maintaining sufficient binding affinity for efficient amplification.
3Reliability
If universal bases are incorporated into primers to prevent allelic dropout, then amplification success rate improves, but primer design complexity increases
Solution Approach 1:
The patent changes the chemical composition parameter of the primer by incorporating universal bases such as inosine, xanthosine, or other non-canonical nucleotides at specific positions. This parameter change allows the primer to bind to multiple alleles while maintaining manageable design complexity through established guidelines for universal base placement and selection.
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 enables accurate gender determination by producing amplification products of distinct lengths, improving the sensitivity and specificity of DNA analysis and avoiding allelic dropout, thereby enhancing the reliability of gender identification.
Implementation Method 1
binding a first primer to a first amelogenin primer binding site in a target nucleic acid sequence; binding a second primer to a second amelogenin primer binding site in said target nucleic acid sequence
Implementation Method 2
amplifying said target nucleic acid, wherein the amplifying yields at least a first amplified sequence
Implementation Method 3
the use of fluorescent labels for detection
Data Source
AI summary
Disclosed are methods for gender determination in the intron 1 region of the amelogenin locus and a newly discovered single nucleotide polymorphism (SNP) within the X chromosome of the amelogenin locus which can cause allelic dropout. Also disclosed are kits useful in gender determination.