@article {36, title = {Characterization and remediation of sample index swaps by non-redundant dual indexing on massively parallel sequencing platforms.}, journal = {BMC Genomics}, volume = {19}, year = {2018}, month = {2018 May 08}, pages = {332}, abstract = {

BACKGROUND: Here we present an in-depth characterization of the mechanism of sequencer-induced sample contamination due to the phenomenon of index swapping that impacts Illumina sequencers employing patterned flow cells with Exclusion Amplification (ExAmp) chemistry (HiSeqX, HiSeq4000, and NovaSeq). We also present a remediation method that minimizes the impact of such swaps.

RESULTS: Leveraging data collected over a two-year period, we demonstrate the widespread prevalence of index swapping in patterned flow cell data. We calculate mean swap rates across multiple sample preparation methods and sequencer models, demonstrating that different library methods can have vastly different swapping rates and that even non-ExAmp chemistry instruments display trace levels of index swapping. We provide methods for eliminating sample data cross contamination by utilizing non-redundant dual indexing for complete filtering of index swapped reads, and share the sequences for 96 non-combinatorial dual indexes we have validated across various library preparation methods and sequencer models. Finally, using computational methods we provide a greater insight into the mechanism of index swapping.

CONCLUSIONS: Index swapping in pooled libraries is a prevalent phenomenon that we observe at a rate of 0.2 to 6\% in all sequencing runs on HiSeqX, HiSeq 4000/3000, and NovaSeq. Utilizing non-redundant dual indexing allows for the removal (flagging/filtering) of these swapped reads and eliminates swapping induced sample contamination, which is critical for sensitive applications such as RNA-seq, single cell, blood biopsy using circulating tumor DNA, or clinical sequencing.

}, keywords = {DNA, Gene Library, Genome, Human, High-Throughput Nucleotide Sequencing, Humans, Sequence Analysis, Sequence Analysis, DNA}, issn = {1471-2164}, doi = {10.1186/s12864-018-4703-0}, author = {Costello, Maura and Fleharty, Mark and Abreu, Justin and Farjoun, Yossi and Ferriera, Steven and Holmes, Laurie and Granger, Brian and Green, Lisa and Howd, Tom and Mason, Tamara and Vicente, Gina and Dasilva, Michael and Brodeur, Wendy and DeSmet, Timothy and Dodge, Sheila and Lennon, Niall J and Gabriel, Stacey} } @article {10, title = {Genome Sequencing of Autism-Affected Families Reveals Disruption of Putative Noncoding Regulatory DNA.}, journal = {Am J Hum Genet}, volume = {98}, year = {2016}, month = {2016 Jan 07}, pages = {58-74}, abstract = {

We performed whole-genome sequencing (WGS) of 208 genomes from 53 families affected by simplex autism. For the majority of these families, no copy-number variant (CNV) or candidate de novo gene-disruptive single-nucleotide variant (SNV) had been detected by microarray or whole-exome sequencing (WES). We integrated multiple CNV and SNV analyses and extensive experimental validation to identify additional candidate mutations in eight families. We report that compared to control individuals, probands showed a significant (p = 0.03) enrichment of de novo and private disruptive mutations within fetal CNS DNase I hypersensitive sites (i.e., putative regulatory regions). This effect was only observed within 50 kb of genes that have been previously associated with autism risk, including genes where dosage sensitivity has already been established by recurrent disruptive de novo protein-coding mutations (ARID1B, SCN2A, NR3C2, PRKCA, and DSCAM). In addition, we provide evidence of gene-disruptive CNVs (in DISC1, WNT7A, RBFOX1, and MBD5), as well as smaller de novo CNVs and exon-specific SNVs missed by exome sequencing in neurodevelopmental genes (e.g., CANX, SAE1, and PIK3CA). Our results suggest that the detection of smaller, often multiple CNVs affecting putative regulatory elements might help explain additional risk of simplex autism.

}, keywords = {Autistic Disorder, DNA, Exome, Female, Genome, Human, Humans, Male, Pedigree, Polymorphism, Single Nucleotide}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.11.023}, author = {Turner, Tychele N and Hormozdiari, Fereydoun and Duyzend, Michael H and McClymont, Sarah A and Hook, Paul W and Iossifov, Ivan and Raja, Archana and Baker, Carl and Hoekzema, Kendra and Stessman, Holly A and Zody, Michael C and Nelson, Bradley J and Huddleston, John and Sandstrom, Richard and Smith, Joshua D and Hanna, David and Swanson, James M and Faustman, Elaine M and Bamshad, Michael J and Stamatoyannopoulos, John and Nickerson, Deborah A and McCallion, Andrew S and Darnell, Robert and Eichler, Evan E} }