Prenatal Paternity Testing Using Fetal cfDNA Likelihood Analysis
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Solution Overview
Problem
Current methods for determining fetal paternity prenatally are invasive and carry a risk of miscarriage, while non-invasive techniques face challenges in isolating and analyzing fetal DNA from maternal blood, which is mixed with maternal DNA, leading to difficulties in accurate genetic analysis.
Innovation Solution
A method involving obtaining genetic material from the alleged father and mother, making genotypic measurements at polymorphic loci, and using maximum likelihood estimation to determine the probability of paternity based on genotypic data from mixed fetal and maternal DNA samples, allowing for non-invasive prenatal paternity testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If invasive procedures such as chorionic villus sampling or amniocentesis are used to obtain fetal genetic material, then genetic analysis can be performed prenatally, but the risk of miscarriage increases
Solution Approach 1:
The patent extracts fetal genetic material (cfDNA) from maternal blood plasma without invasive procedures. The method isolates and analyzes cell-free DNA fragments circulating in maternal blood that originate from the fetus, enabling prenatal genetic testing while avoiding the miscarriage risks associated with invasive sampling techniques.
2Object-affected harmful factors
If non-invasive methods using maternal blood are used to obtain fetal DNA, then miscarriage risk is eliminated, but the fetal DNA concentration is very low (1-40 cells per milliliter) making isolation and analysis difficult
Solution Approach 1:
The patent replaces traditional mechanical cell isolation methods with molecular-based detection. Instead of physically isolating rare fetal cells from maternal blood, the method uses PCR amplification and genetic fingerprinting to detect and analyze fetal-specific DNA sequences directly from the mixed cfDNA population in maternal plasma, overcoming the low concentration challenge.
3Ease of operation
If fetal cfDNA is analyzed directly from maternal blood, then non-invasive testing is achieved, but the maternal genotypic signal interferes with accurate fetal DNA analysis
Solution Approach 1:
The patent applies local quality by targeting specific fetal-specific genetic sequences within the mixed DNA population. The method uses polymorphic markers and paternal-specific sequences to identify and analyze only the fetal contribution to the cfDNA mixture, effectively filtering out the maternal background signal and enabling precise fetal genetic analysis.
4Quantity of substance
If traditional cell isolation techniques such as density centrifugation or FACS are used to enrich fetal cells, then some fetal cells can be isolated, but the enrichment to high purity is difficult to achieve
Solution Approach 1:
The patent replaces mechanical enrichment techniques (density centrifugation, FACS) with molecular amplification and specific sequence detection. By using PCR to amplify fetal-specific DNA sequences and genetic fingerprinting to identify paternal markers, the method achieves high purity fetal DNA analysis without relying on physical cell separation, which is limited by the rarity and similarity of fetal cells in maternal blood.
Data Source
AI summary
Methods for non-invasive prenatal paternity testing are disclosed herein. The method uses genetic measurements made on plasma taken from a pregnant mother, along with genetic measurements of the alleged father, and genetic measurements of the mother, to determine whether or not the alleged father is the biological father of the fetus. This is accomplished by way of an informatics based method that can compare the genetic fingerprint of the fetal DNA found in maternal plasma to the genetic fingerprint of the alleged father.