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Multiplex padlock targeted sequencing reveals human hypermutable CpG variations.

ABSTRACT: Utilizing the full power of next-generation sequencing often requires the ability to perform large-scale multiplex enrichment of many specific genomic loci in multiple samples. Several technologies have been recently developed but await substantial improvements. We report the 10,000-fold improvement of a previously developed padlock-based approach, and apply the assay to identifying genetic variations in hypermutable CpG regions across human chromosome 21. From approximately 3 million reads derived from a single Illumina Genome Analyzer lane, approximately 94% (approximately 50,500) target sites can be observed with at least one read. The uniformity of coverage was also greatly improved; up to 93% and 57% of all targets fell within a 100- and 10-fold coverage range, respectively. Alleles at >400,000 target base positions were determined across six subjects and examined for single nucleotide polymorphisms (SNPs), and the concordance with independently obtained genotypes was 98.4%-100%. We detected >500 SNPs not currently in dbSNP, 362 of which were in targeted CpG locations. Transitions in CpG sites were at least 13.7 times more abundant than non-CpG transitions. Fractions of polymorphic CpG sites are lower in CpG-rich regions and show higher correlation with human-chimpanzee divergence within CpG versus non-CpG sites. This is consistent with the hypothesis that methylation rate heterogeneity along chromosomes contributes to mutation rate variation in humans. Our success suggests that targeted CpG resequencing is an efficient way to identify common and rare genetic variations. In addition, the significantly improved padlock capture technology can be readily applied to other projects that require multiplex sample preparation.

SUBMITTER: Li JB

PROVIDER: S-EPMC2752131 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Multiplex padlock targeted sequencing reveals human hypermutable CpG variations.

Li Jin Billy JB Gao Yuan Y Aach John J Zhang Kun K Kryukov Gregory V GV Xie Bin B Ahlford Annika A Yoon Jung-Ki JK Rosenbaum Abraham M AM Zaranek Alexander Wait AW LeProust Emily E Sunyaev Shamil R SR Church George M GM

Genome research 20090612 9

Utilizing the full power of next-generation sequencing often requires the ability to perform large-scale multiplex enrichment of many specific genomic loci in multiple samples. Several technologies have been recently developed but await substantial improvements. We report the 10,000-fold improvement of a previously developed padlock-based approach, and apply the assay to identifying genetic variations in hypermutable CpG regions across human chromosome 21. From approximately 3 million reads deri ...[more]

PMID: 19525355

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Project description:Whole transcriptome RNA-sequencing is a powerful tool, but is costly and yields complex data sets that limit its utility in molecular diagnostic testing. A targeted quantitative RNA-sequencing method that is reproducible and reduces the number of sequencing reads required to measure transcripts over the full range of expression would be better suited to diagnostic testing. Toward this goal, we developed a competitive multiplex PCR-based amplicon sequencing library preparation method that a) targets only the sequences of interest and b) controls for inter-target variation in PCR amplification during library preparation by measuring each transcript native template relative to a known number of synthetic competitive template internal standard copies. To determine the utility of this method, we intentionally selected PCR conditions that would cause transcript amplification products (amplicons) to converge toward equimolar concentrations (normalization) during library preparation. We then tested whether this approach would enable accurate and reproducible quantification of each transcript across multiple library preparations, and at the same time reduce (through normalization) total sequencing reads required for quantification of transcript targets across a large range of expression. We demonstrate excellent reproducibility (R²?=?0.997) with 97% accuracy to detect 2-fold change using External RNA Controls Consortium (ERCC) reference materials; high inter-day, inter-site and inter-library concordance (R²?=?0.97-0.99) using FDA Sequencing Quality Control (SEQC) reference materials; and cross-platform concordance with both TaqMan qPCR (R²??=?0.96) and whole transcriptome RNA-sequencing following "traditional" library preparation using Illumina NGS kits (R²?=?0.94). Using this method, sequencing reads required to accurately quantify more than 100 targeted transcripts expressed over a 10?-fold range was reduced more than 10,000-fold, from 2.3×10? to 1.4×10? sequencing reads. These studies demonstrate that the competitive multiplex-PCR amplicon library preparation method presented here provides the quality control, reproducibility, and reduced sequencing reads necessary for development and implementation of targeted quantitative RNA-sequencing biomarkers in molecular diagnostic testing.

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Multiplex padlock targeted sequencing reveals human hypermutable CpG variations.

Publications

Multiplex padlock targeted sequencing reveals human hypermutable CpG variations.

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