Whole exome sequencing (WES) is targeted to protein coding regions only. If unlimited resources and time, whole genome sequencing (WGS) is still preferable over whole exome sequencing as it allows you to interrogate single-nucleotide variants (SNVs), indels, structural variants (SVs) and copy number variants (CNVs) in both the ~1% part of the genome that encodes protein sequences and the ~99% of remaining non-coding sequences. However, whole exome sequencing still costs a lot less than WGS, allowing researchers to increase sample number, an important factor for large population studies. WES does however have its limitations as it is based on probes capturing the protein coding sequences. Due to differences in the hybridization efficiency of these probes this can result in regions of the genome with little or no coverage. Additionally WES suffers from reference bias as capture probes tend to preferentially enrich reference alleles at heterozygous sites producing false negative SNV calls.
Advantages of Whole Exome Sequencing
- Reduced cost per sample as only the protein coding regions are targetted and sequenced
- Reduced costs allow to sequence target regions at a higher depth at the same cost
- Reduced costs make it feasible to increase the number of samples to be sequenced, enabling large population based comparisons
Whole Exome Sequencing Workflow
First, we will perform a quality analysis of the DNA samples provided to us by you. We will need at least 1µg of DNA. Only when the provided genomic DNA is of sufficient quality and quantity will we proceed with the next steps. In case the DNA provided to us is of insufficient quality and/or quantity, we will contact you and discuss how to proceed.
Then, the DNA contained within the exome will be captured, and sequencing libraries are prepared by adding indexes and primer adapters. After another quality assessment step these libraries are sequenced on one of our Illumina Sequencers. The technical quality of the sequencing run is monitored in real time.
Sequencing data can be transferred to you via the Illumina BaseSpace platform or our own server (FTP download).
Feel free to contact us for more information.