Exome-Sequencing

Exome sequencing, or WES (Whole Exome Sequencing) for short, is a genomic technique for sequencing all protein-coding regions of genes in a genome - the exome. It comprises only about 1-2% of the entire genome (approx. 22,000 genes) and is much more highly conserved in its sequence than in the non-coding regions of the DNA. Around 85% of known disease-causing mutations, some of which can lead to serious diseases, are also found in this region. WES is an important molecular tool for research questions in medicine, for clinical studies and for the development of drugs.

A variation in a protein-coding region can cause different genetic diseases. In addition to identifying such disease-causing variants, whole exome sequencing is also used to answer research questions. These include the analysis of rare variants associated with complex traits or the further development of personalized medicine. Whole exome sequencing is also used to monitor the success of a therapy.

The exonic regions contain the majority of genetic changes that lead to disease phenotypes, including large genetic variants, copy number variations (CNVs), small insertions and deletions (indels), single nucleotide polymorphisms (SNPs) and single nucleotide variants (SNVs).

The technique used in whole exome sequencing consists of two steps. In the first step, the regions that code for proteins, i.e. the exons, are recorded. The detected targets are isolated, washed and eluted. After amplification, these targets are used in the second step - the sequencing of the exomic DNA.

Whole exome sequencing has several advantages over other technologies that can be used to identify genetic variants. In contrast to microarray-based genotyping, Whole Exome Sequencing can identify unexpected genetic changes. The previous limitations of microarray-based genotyping can therefore be overcome with Whole Exome Sequencing. Compared to Whole Genome Sequencing, Whole Exome Sequencing shows the large difference between the proportion of exonic and intronic regions: in exome sequencing, only 1 %-2 % of the entire genome is sequenced. This enables a higher sequencing depth and at the same time reduces the sequencing costs.