Exome sequencing is a technique used to determine the sequence of DNA sequences in an individual's genetic code and to detect genetic defects.
Exome sequencing is a technique used to determine the sequence of DNA sequences in an individual's genetic code and to detect genetic defects. Today, this technique is applied in the health sector to determine genetic variations and is used more in research. For this reason, many of the mutations known to trigger the disease occur in the exome. Exome sequencing is thought to be an effective technique for identifying disease-causing mutations. Continuous examination of exome and genome sequences will aid disease diagnosis in the future. In addition, it determines whether new genetic variations are associated with health conditions.
The exome sequencing technique allows the identification and information of variations in the protein-coding region of any gene, not just a select few genes. Exome sequencing has
proven successful in identifying novel causative mutations for previously undetected unknown diseases with whole-exome sequencing technology targeting protein-coding regions of the genome. In particular, it has the potential to increase the ability to act as a preventative before disease development or to initiate treatment for an as-yet undiagnosed disease. Accordingly, coding variants can be efficiently identified in a wide range of applications, including genetic disease and cancer studies, by exome sequencing. This method is one of the new-generation sequencing methods for the detection of genetic diseases and diseases for which many genes are responsible, especially in patients that cannot be diagnosed by clinical and laboratory examinations. In this context, the interpretation of exome sequencing data with the relevant method and the accurate and safe reporting of the findings per patient requires expertise in genomic informatics and clinical medicine. In addition, the test can also interpret situations such as genetic cancer predispositions, evaluation of risky pregnancy/childhood status of individuals with consanguineous marriages, and detection of patients who may require clinical follow-up. The purpose of this test is to conclude 20,500 genes at once, at less cost and in a short time, according to 2021 data.
Evaluation of exome sequencing data; It is carried out in the light of current scientific data according to the clinical findings and family histories of the individuals. Today, 8,000 of the more than 20,500 genes in humans are known to be associated with diseases. The diseases/findings investigated in the patient are evaluated in terms of the findings of the cases reported in the literature, and the pathogenicity of the detected variants is reported according to the criteria of in silico evaluation tools (SIFT, PolyPhen-2, MutationTaster, MetaLR..) and ACMG (American College of Medical Genetics). As a result of these studies, it is possible to determine the treatment methods, if any, for the diagnosis of the patient, to detect the individuals at risk of disease/carrier by screening family members, and to prevent this disease in the next pregnancies of the family. The results of these analyses take
approximately 1-2 months under normal conditions.
In exome sequencing;
• Sequence analysis of 20,500 genes
• Copies Variations
• Clinically significant HLA variants are evaluated.
In analysis;
• Variants that can explain the patient's clinical findings
• If the person wishes, variants that will be important in his future life and can be treated (https://www.ncbi.nlm.nih.gov/clinvar/docs/acmg/ web page and similar) are reported.
The analysis consists of four stages;
• Data generation in the laboratory
• Bioinformatics
• Clinical evaluation
• Confirmation
For a quality analysis;
• Resolution of the data produced in the laboratory
• Elaboration of data in bioinformatics, quality assessment, and identification of high-risk variants
• Review of the process and clinical perspective by a physician experienced in patient examination and evaluation.
• Additional analyzes required for confirmation of the data obtained, family screening, and evaluation of the pathogenicity of the detected variant (requesting and evaluation of additional tests such as RNA sequencing, Western Blot, X-ray from the patient, biochemistry)
• Having statistics obtained from the data held by the center
• The data of undiagnosed or suspected patients should be reviewed at appropriate intervals and reinterpreted in the light of current literature.
Reporting;
It is the process of transforming the data obtained by the analysis team into a clinical report that is beneficial to the patient and clinician. Reports containing the necessary data are prepared for the correct interpretation of the selected variants from a data stack and for guiding the clinician.