Genes are the regions on DNA that are responsible for the coding of proteins. Within each gene, there are sub-regions called exons and introns. Intron regions are removed during the production of proteins and introns do not take place in the final form of the protein. The actual code that constitutes the protein is located in the exon regions. Exome is the totality of the DNA sequences of the genes that enable the production of proteins necessary for the function of the body.
2% of the human genome corresponds to protein-coding genes; this refers to about 200,000 exons of about 20,000 genes. Exome sequencing is the sequence of protein-coding regions of all of a human-owned genes. With this test, whole exons of the total genome is sequenced. This means a sequencing process of approximately 20,000 genes and 650 million nucleotides per person.
Most of the genetic tests performed until recently scan only a single gene or several genes thought to be related to the disease, while WES tests scan thousands of genes simultaneously. This makes WES one of the most effective methods to identify the causes of complex genetic problems. The WES test is ideal for finding new mutations and identifying atypical signs of the disease. With WES analysis, all exons in the human genome are subjected to sequence analysis and are of great importance for the definitive diagnosis of the disease, especially in patients who have not been clinically diagnosed. In families carrying genetic disease, it is important to make a definitive diagnosis by mutation detection of the disease in order to maintain a healthy lineage of the family. In addition, the presence of the gene responsible for the disease enables the determination of whether the baby is sick or not in the in vitro fertilization stage in the new pregnancies of families with sick children and the disease can be prevented by genetic examination.
After obtaining DNA from different biological materials such as blood, tissue or saliva samples, exome data is obtained by a next generation sequencing (NGS) system. Genetic variant lists in the person are prepared (Standard bioinformatics), then these genetic variants are interpreted with clinical data (Clinical bioinformatics) and finally a clinical report is prepared to the patient.