This test involves reanalysis and interpretation of previously generated data from an outside laboratory whole exome sequencing test. All variants identified will be analyzed according to American College of Medical Genetics and Genomics (ACMG) guidelines. In addition to SNVs, our WES analysis will attempt to reliably detect CNVs of 3 exons or greater. Smaller CNV events may also be detected and reported, but additional follow-up testing is recommended if a smaller CNV is suspected. Due to differences in laboratory sequencing protocols and procedures, it is possible that additional limitations will be detected. It is recommended that updated clinical notes and phenotypes are provided to aid in the reanalysis.

Whole exome sequencing is performed by an external laboratory and the FASTQ files are provided directly to Revvity Omics. A base is considered to have sufficient coverage at 20X and an exon is considered fully covered if all coding bases plus three nucleotides of flanking sequence on either side are covered at 20X or more. A list of these regions, if any, is available upon request. Alignment to the human reference genome (GRCh37) is performed and annotated variants are identified in the targeted region. Variants reviewed have a minimum coverage of 8X and an alternate allele frequency of 20% or higher. Indel and single nucleotide variants (SNVs) may be confirmed by Sanger sequence analysis before reporting at director discretion. This assay cannot detect variants in regions of the exome that are not covered, such as deep intronic, promoter and enhancer regions, areas containing large numbers of tandem repeats, and variants in mitochondrial DNA. Copy number variation (CNV) analysis detects deletions and duplications; in some instances, due to the size of the exons, sequence complexity, or other factors, not all CNVs may be analyzed or may be difficult to detect. When reported, copy number variant size is approximate. Actual breakpoint locations may lie outside of the targeted regions. CNV analysis will not detect tandem repeats, balanced alterations (reciprocal translocations, Robertsonian translocations, inversions, and balanced insertions), methylation abnormalities, triploidy, and genomic imbalances in segmentally duplicated regions. This assay is not designed to detect mosaicism; possible cases of mosaicism may be investigated at the discretion of the laboratory director. The external FASTQ data is analyzed using Illumina DRAGEN Bio-IT Platform v.3.10.8. Tertiary data analysis is performed using SnpEff v5.0 and Revvity Omics’ internal ODIN v.1.01 software. CNV and absence of heterozygosity are assessed using BioDiscovery’s NxClinical v6.1 software.