Genotyping Intensity Normalization for Heterozygous Accuracy
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Solution Overview
Problem
Current genotyping methods face challenges in accurately calling heterozygous genotypes due to asymmetry in intensity measurements between alleles, leading to frequent 'no calls' and reduced accuracy in identifying heterozygous loci.
Innovation Solution
The method involves a normalization step where intensity measurements for one allele are adjusted using reference ratios calculated from a training set, allowing for improved genotype calling by minimizing asymmetry and enhancing the ability to identify heterozygous polymorphisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intensity measurements are used directly for genotype calling, then the process is simple and fast, but the accuracy of heterozygous genotype calling is poor due to asymmetry between alleles
Solution Approach 1:
The patent applies preliminary action by performing a normalization step before genotype calling. Reference ratios are calculated from training data in advance, and these pre-computed ratios are then used to adjust test intensity measurements. This preliminary preparation of normalization factors resolves the asymmetry problem without adding complexity to the actual genotype calling process.
Solution Approach 2:
The patent changes the parameter of intensity measurements by applying a normalization transformation. The raw intensity values are adjusted using reference ratios to produce normalized intensity measurements that account for allele-specific asymmetry. This parameter transformation improves measurement precision while maintaining a relatively simple processing pipeline.
2Reliability
If no normalization is applied, then the genotyping process is quick and straightforward, but heterozygous loci are frequently misclassified or result in 'no calls'
Solution Approach 1:
The normalization factors are pre-calculated from training data, allowing rapid adjustment of test samples. This preliminary action ensures reliable genotype calling without requiring time-consuming iterative adjustments during actual genotyping, thus maintaining efficiency while improving reliability.
Solution Approach 2:
The patent uses feedback from training data to establish reference ratios that reflect the true relationship between allele intensities. This feedback mechanism allows the system to learn and correct for systematic biases, improving genotype call reliability while the pre-computed nature of the feedback keeps processing time minimal.
3Measurement precision
If intensity measurements are adjusted using reference ratios, then heterozygous genotype accuracy improves, but the computational steps increase
Solution Approach 1:
The patent applies a straightforward parameter transformation by multiplying intensity measurements by pre-computed reference ratios. This simple mathematical adjustment corrects for allele-specific asymmetry and improves heterozygous genotype accuracy without introducing complex normalization procedures. The method maintains computational simplicity while achieving high measurement precision.
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 significantly improves the accuracy of genotyping, particularly for heterozygous loci, by reducing 'no calls' and enhancing the reliability of genotype calls, as demonstrated by substantial improvements in genotyping quality.
Implementation Method 1
The intensity measurements represent intensity of signal associated with one or more features on said genotyping array
Data Source
AI summary
Methods for genotyping polymorphisms using allele specific probes are disclosed. A training set is used to generate a model for each polymorphism to be interrogated. The training set is used to obtain an estimate of the asymmetry between an intensity measurement for a first allele and an intensity measurement for a second allele of the same polymorphism. The intensity measurement obtained for a test sample is adjusted using the estimate of asymmetry prior to using the intensity measurements to make a genotyping call. In preferred embodiments the adjustment is applied to polymorphisms that have a likelihood of being heterozygous that is above a specified threshold.