Whole Genome & Whole Exome Sequencing (WGS & WES)
What do we mean by "Whole Exome Sequencing (WES)"?
This test involves identifying the sequence of the entire human coding (exon) genome, that is, all the genomic regions that "give the necessary commands" for the production of proteins that mediate the proper functioning of the human body. Changes in the sequence of these regions, which are referred to as pathogenic mutations, can cause changes in the structure of the proteins produced that make them non-functional / partially functional or completely inhibit their production. In particular, WES covers about 85% of the pathogenic mutations associated with the onset of the disease, although WES "represents" less than 2% of the human genome.
Conducting WES requires the use of Next-Generation-Sequencing (NGS) technology, which enables the export of large volumes of sequencing data. The processing of this data is carried out with specialized algorithms (BWA, GATK4, Freebayes), the use of which results in an extensive list of mutations, along the entire length of the encoding human genome.
The following is a description of these mutations (variant annotation), in terms of the likelihood that they are associated with the onset of clinical symptoms, with the help of a number of international scientific databases, some of which are: "Ensembl Variant Effect Predictor", "1000 Genomes Project" , “Exome Variant Server database”, “Exome Aggregation Consortium”, “Combined Annotation Dependent Depletion” (CADD), “OMIM”, “Orphanet”.
The preference of WES over WGS has so far been based solely on high cost. This obstacle tends to be removed as WGS is now offered at a cost approaching WES, well below € 1000.
Whole Genome Sequencing (WGS) involves the complete sequencing of the human genome, both exons and introns, in which more and more pathogenic mutations are now detected.