Sequencing Intensity Normalization via Transfer Functions

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Solution Overview

Problem

Next-generation sequencing (NGS) technologies face challenges in accurately deducing nucleotide sequences due to channel-specific bias and noise, which current correction methods cannot fully address, especially when unknown phenomena introduce systematic offsets and fluctuations.

Innovation Solution

A method for normalizing intensity values by parametrizing and combining channel-specific intensity distributions to create a common distribution, using transfer functions to map each channel's intensity to this common distribution, thereby reducing bias and noise effects without requiring knowledge of the specific biasing phenomena, and applying smoothing functions across cycles to maintain consistent intensity levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If model-based correction approaches (background correction and crosstalk correction) are used, then known bias phenomena can be corrected, but unknown biasing phenomena cannot be addressed

Engineering Contradiction:
Improvebase-calling accuracyVSAvoidability to handle unknown bias phenomena
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system performs self-correction by using the observed intensity distributions themselves to identify and correct biases. The method calculates median intensities and determines correction factors from the data without requiring external knowledge of bias sources, allowing the system to adapt to both known and unknown biasing phenomena automatically

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention transforms the correction approach by changing from model-based parameters (assuming known bias mechanisms) to data-driven parameters (using observed intensity distributions). By parametrizing the intensity distributions and using empirical statistics like medians, the system can adapt to any bias pattern present in the data regardless of its origin

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If channel-specific correction models are applied, then systematic offsets can be corrected for known phenomena, but the complexity of the correction algorithm increases

Engineering Contradiction:
Improveintensity profile accuracyVSAvoidcorrection algorithm complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The method extracts only the essential correction information (median intensities and correction factors) from the intensity distributions, separating the critical normalization step from complex model-based corrections. This extraction approach simplifies the algorithm by focusing only on what is necessary for effective normalization

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of applying complex forward models to predict and correct biases, the invention inverts the approach by directly observing the intensity distributions and deriving correction factors from the data itself. This reverse engineering approach simplifies the algorithm by working from observed effects rather than theoretical models

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP3642746B1Method and apparatus for performing a normalization in the context of sequencing analysis
Publication Date: 2023.11.01 QIAGEN GMBH
  • EP3642746B1 patent drawingFigure 1a
  • EP3642746B1 patent drawingFigure 1b
  • EP3642746B1 patent drawingFigure 1c

AI summary

A method for performing a normalization of intensity values obtained to perform sequencing analysis comprises the steps: receiving (110) a plurality of image data for a plurality of channels, each image data (11a-11d, 15a-15d) describes for the respective channel (a-d) an intensity distribution over all positions of an image of the a plurality of image data (11 a-11 d, 15a-15d); parametrization (120) of the intensity distribution over all positions for the plurality of channels (a-d) to obtain parametrized distributions for the plurality of channels (a-d); combining (130) the parametrized distributions for the plurality of channels (a-d) to obtain a common distribution for all of the plurality of channels (a-d); and determining (140) for each of the plurality of channels (a-d) a transfer function such that the respective transfer function for the respective channel (a-d) maps the corresponding intensity distribution to the common distribution.