Whole Exome Sequencing

Via whole exome sequencing (WES), it is possible to reduce the genomic information to only the coding DNA. While the majority of all known disease causing mutations are located in coding regions, it only makes up approximately 1% of the entire human genome. So, despite the fact this procedure is more complex than whole genome sequencing (WGS), it is more cost beneficial since the sequencing cost is vastly reduced.

The WES procedure is different from the WGS procedure, in the sense that an extra PCR and capturing step is performed on the shotgun WGS library. For this, target specific biotinylated ssDNA probes (50-100 nt) are added to enrich for the coding regions. Blocking oligonucleotides prevent enrichment of both repetitive sequences (using COT-1) as adapter mediated co-enrichment of noncoding DNA (using reverse complement adapter sequences). Via magnetic streptavidin beads, all biotinylated ssDNA probes - hybridized to their complementary targets of interest - are selected and non-hybridized DNA is washed away. Following PCR, sufficient material is obtained to proceed to massive parallel sequencing (MPS), where 2x125 bp reads are generated.

Methodology

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Minimum requirements

Following are the minimum requirements for us to proceed with WES. If compliance with any of the following points is not possible, please contact us up front.

 

  • Amount : at least 2 µg DNA (determined fluorometrically, eg. Qubit)

    • Exceptions are possible for precious samples, however we ought to be informed/contacted up front

  • Concentration : should exceed or be equal to 30 ng/µl

  • DNA should not be degraded

  • At least 2 identifiers are required to identify the sample (eg. unique lab number + [surname+name, initials , date of birth,…])

  • A sample list should be provided to us digitally (all delimiters should be included in this list)

    • Please download sample submission form here or see "Downloads" section

  • Tubes should be labelled correctly (with 2 identifiers), preferably with a printed label

  • Per biological sample, only 1 tube should be shipped (no multiple aliquots of the same sample)

Compatible platforms

WES is performed on the Illumina HiSeq and the Illumina NovaSeq 6000.

Kits

Our routine WES procedure uses the following kits :

  • KAPA Hyper prep

  • Roche SeqCap EZ Human Exome v3.0 (64 Mb)

BRIGHTcore / T +32 (0)2 477 64 79 / F +32 (0)2 477 68 59 / © 2015 by BRIGHTcore

Photography / Bart Moens / http://www.fotobart.be

Content & illustrations / Ben Caljon