Exome sequencing includes the sequencing of the protein coding regions and their flanking intronic regions in ~20,000 genes of the human genome. The coding region represents 1-2% of the human genome but contains approximately 85% of disease-causing mutations. Exome sequencing is performed on the HiSeq 2500 sequencer, Illumina Inc with the following characteristics: 70x mean read coverage, target region size 37 Mb, 214,405 target exons.
Trio exome sequencing of family members, usually affected child with parents is highly recommended for faster and more precise identifying of disease-causing mutation and determining the pattern of inheritance. In addition to patient’s phenotype/disease associated variants, incidental findings are reported according to ACMG recommendations for reporting of incidental findings in clinical exome and genome sequencing.
Exome sequencing can be an efficient tool for clinicians to confirm patients’ diagnosis of complicated conditions not covered by conventional testing approaches.
Indications for genetic testing:
1. Confirmation of clinical diagnosis
2. Diagnosing of genetically and phenotypically heterogeneous group of disorders
3. Testing patients with atypical phenotype
4. Diagnosis of patients with genetic disorders for which diagnostic panels are not available
5. Genetic counseling