Methodology
- Molecular Genetics
- DDeletion/duplication analysis
- Next-Generation (NGS)/Massively parallel sequencing (MPS)
- CSequence analysis of the entire coding region
- Next-Generation (NGS)/Massively parallel sequencing (MPS)
- TTargeted variant analysis
- Bi-directional Sanger Sequence Analysis
- Applied Biosystems 3730 capillary sequencing instrument
Test developed by laboratory (no manufacturer test name)
For the PGxome we use Next Generation Sequencing (NGS) technologies to cover the coding regions of targeted genes plus ~10 bases of non-coding DNA flanking each exon. As required, genomic DNA is extracted from patient specimens. Patient DNA corresponding to these regions is captured using Agilent Clinical Research Exome hybridization probes. Captured DNA is sequenced on the NovaSeq 6000 using 2x150 bp paired-end reads (Illumina, San Diego, CA, USA). The following quality control metrics are generally achieved: >97% of target bases are covered at >20x, and mean coverage of target bases >120x. Data analysis and interpretation is performed by the internally developed Infinity pipeline. Variant calls are made by the GATK haplotype caller (through Sentieon) and annotated using in house software and Jannovar. Common benign, likely benign, and low quality variants are filtered from analysis. All reported pathogenic, likely pathogenic, and variants of uncertain significance are confirmed by Sanger sequencing. For Sanger sequencing, polymerase chain reaction (PCR) is used to amplify targeted regions. After purification of the PCR products, cycle sequencing is carried out using the ABI Big Dye Terminator v.3.0 kit. PCR products are resolved by electrophoresis on an ABI 3730xl capillary sequencer. In nearly all cases, cycle sequencing is performed separately in both the forward and reverse directions. Copy number variants (CNVs) are also detected from NGS data. We utilize a CNV calling algorithm that compares mean read depth and distribution for each target in the test sample against multiple matched controls. Neighboring target read depth and distribution and zygosity of any variants within each target region are used to reinforce CNV calls. All CNVs are confirmed using another technology such as aCGH, MLPA, or PCR before they are reported. Our most favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please contact us (clinicaldnatesting@preventiongenetics.com) for Test Code, pricing, and turnaround time information.
Citations
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