Clinical information
Diagnostic Utility:
Identifying genetic variants related to a disease or haemostatic disorder.
Whole Exome Sequencing (WES) is based on the capture of fragmented DNA, obtained from total blood, through the hybridization of specific probes. This test allows for the sequencing of the entire human exome, which includes genomic regions encoding proteins and contains approximately 85% of known disease-causing variants. This design offers cost-benefit advantages compared to other gene panel sequencing techniques, as it allows for the updating of candidate gene selection and the reanalysis of results based on current knowledge.
This test is particularly indicated in cases of diseases with different candidate genes or with a phenotype lacking clear genetic basis. The main application is the diagnosis of genetically heterogeneous or poorly understood haemorrhagic diatheses such as hereditary platelet disorders, congenital glycosylation defects, or connective tissue deficiencies. Since this approach can be used in the diagnosis of various diseases, you can consult its application with the laboratory responsible.
Especially in the study of complex phenotypes or in cases of difficult assessment of identified variants, trio analysis (patient and two direct family members) is recommended. This strategy can simplify and enhance analyses, providing information on the inheritance of the disease.
Method:
Massive sequencing of exons and flanking intronic regions of all genes.
Traditional Sanger sequencing to confirm the candidate mutation(s) detected by NGS in patients, in order to arrive at an unequivocal result. Specific primer design may be necessary to analyze the specific region where the variant is located.
If no candidate mutation potentially causing the pathology is identified, it will be reported and discussed with the requesting medical team the possibility of performing additional studies.
Reference Values
Not applicable
Diagnostic Algorithm:
Not applicable
Turnaround Time:
To be determined
Specimen information
Sample: Whole blood
Tube: EDTA K3 tube 5-10 ml if it is a blood sample
Minimum essential volume: 3 ml
Stability:
- At room temperature: 4 days
- In refrigeration: 10 days
Transport instructions: Preferably at room temperature
Reason for rejection: Coagulated sample and/or incorrectly identified sample.
Other accepted sample types:
- Purified DNA, minimum 300 ng (30 ng/µL)
- Buccal mucosa: contact the laboratory to inquire about sample collection specifications.
Administrative information
BST Code: LRD2829
Test Description: Complete Exome
Synonyms: Whole exome sequencing, WES, molecular study of genetically based diseases.
Section: Congenital Coagulopathies
BST Fee: Check the updated fees here.
In the molecular study request form, the Other box must be checked, specify that the complete exome is to be studied, and fill in (attach) the phenotypic data available.
Profiles:
Not applicable.
References
- LaDuca H, Farwell KD, Vuong H, Lu HM, Mu W, Shahmirzadi L, Tang S, Chen J, Bhide S, Chao EC. Exome sequencing covers >98% of mutations identified on targeted next generation sequencing panels. PLoS One. 2017;12(2):e0170843.
- Protocolo Nextera Flex for Enrichment Reference Guide (1000000048041) de Illumina.
Base de dades de mutacions
- Human Gene Mutation Database: http://www.hgmd.cf.ac.uk
- Leiden Open Variation Database: https://databases.lovd.nl/shared/genes
- Genome Aggregation Database: https://gnomad.broadinstitute.org
- 1000 Genomes Database: https://www.internationalgenome.org