Genomic Rearrangement Detection via Paired-End Ditags
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Solution Overview
Problem
Current methods are inadequate for accurately detecting chromosomal rearrangements and translocations, which are associated with various diseases and cancers, as they lack sensitivity and specificity in identifying genetic abnormalities at a genome-wide level.
Innovation Solution
The method involves capturing and amplifying a chromosome from a sample using hybrid selection and then hybridizing the captured material to a whole-genome tiling array to assess for translocations and large-scale rearrangements by generating and sequencing paired-end ditags, which are compared to the reference human genome sequence to identify variant fragments indicative of rearrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional cytogenetics and karyotyping methods are used to detect translocations, then the detection process is relatively simple, but the sensitivity and specificity in identifying genetic abnormalities at a genome-wide level is insufficient
Solution Approach 1:
The method segments the complex task of detecting all types of chromosomal rearrangements into distinct analytical steps: (1) capturing and amplifying specific chromosomes using hybrid selection, (2) generating paired-end ditags from restriction fragments, (3) hybridizing to whole-genome tiling arrays, and (4) bioinformatic analysis. This segmentation allows each step to be optimized independently while achieving comprehensive detection capability.
Solution Approach 2:
The patent introduces several intermediary components that bridge the gap between simple detection and comprehensive analysis: (1) hybrid selection probes as intermediaries to capture specific chromosomes, (2) paired-end ditags as intermediaries to encode restriction fragment information, and (3) whole-genome tiling arrays as intermediaries to provide comprehensive genomic coverage. These intermediaries enable the system to achieve high sensitivity and specificity without requiring direct complex analysis of entire genomes.
2Measurement precision
If hybrid selection and whole-genome tiling arrays are used to detect translocations, then detection sensitivity and specificity are improved, but the assay complexity and time required increase
Solution Approach 1:
The method performs preliminary actions that prepare the sample in advance for comprehensive analysis: (1) capturing and amplifying specific chromosomes before analysis, (2) generating paired-end ditags that encode restriction fragment information, and (3) preparing the DNA for hybridization to tiling arrays. These preliminary steps organize the complex information in advance, allowing for faster and more accurate detection when the actual analysis is performed.
3Adaptability or versatility
If paired-end ditag sequencing is performed to identify all rearrangements, then comprehensive assessment of chromosomal changes is achieved, but the complexity of data analysis increases
Solution Approach 1:
The method creates a simplified copy of the complex genomic information through paired-end ditags. Each restriction fragment is represented by two short tags (approximately 18 bp each) from its ends, which are ligated together to form a ditag. This copying process reduces the complex genomic data into manageable units that can be systematically analyzed against the reference sequence to identify rearrangements.
Solution Approach 2:
The analysis process incorporates feedback mechanisms where the observed ditag sequences are compared against the reference human genome sequence. Variant ditags that do not match the reference indicate potential rearrangements, and this feedback loop allows the system to systematically identify and characterize different types of chromosomal abnormalities including translocations, insertions, deletions, and inversions.
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 the detection of translocations and rearrangements with high sensitivity and specificity, allowing for the identification of genetic abnormalities that may contribute to diseases and cancers, providing a comprehensive assessment of chromosomal changes.
Implementation Method 1
hybridizing the captured material to a whole-genome tiling array
Implementation Method 2
digest a genomic DNA of interest with a restriction enzyme
Implementation Method 3
hybridize the population of ditags to a 'ditag sequencing array'
Data Source
AI summary
Methods for detecting genomic rearrangements are provided. In one embodiment, methods are provided for the use of paired end tags from restriction fragments to detect genomic rearrangements. Sequences from the ends of the fragments are brought together to form ditags and the ditags are detected. Combinations of ditags are detected by an on-chip sequencing strategy that is described herein, using inosine for de novo sequencing of short segments of DNA. In another aspect, translocations are identified by using target specific capture and analysis of the captured products on a tiling array.