//Test Details
WES - Additional Affected Sibling
What is WES - Additional Affected Sibling?
The WES - Additional Affected Sibling test is a highly complex test that is developed for the identification of changes in a patient's DNA that are causative or related to their medical concerns. In contrast to panel sequencing tests that analyze one gene or small groups of related genes at a time, WES will analyze the exons (coding regions) of thousands of genes simultaneously using next-generation sequencing techniques.

This test should be ordered along with or after a completed Trio (test code 1600) for the same biological family. The sibling is expected to be symptomatic but may not have the exact same symptoms as the proband. In general, the test is used when a patient's medical history and physical exam findings suggest an underlying genetic etiology. In some cases, the patient may have had an extensive evaluation consisting of multiple genetic tests, without identifying an etiology. If a complete Trio is not able to be sent with or before the Sibling Trio, a physician may opt to order the proband only whole exome sequencing test (test code 1500) to expedite a possible diagnosis.

The exome refers to the portion of the human genome that contains functionally important DNA sequences that direct the body to make proteins essential for the body to function properly. These regions of DNA are referred to as exons. There are approximately 180,000 exons in the human genome which represents about 3% of the genome. These 180,000 exons are arranged in about 22,000 genes. It is known that most of the errors in DNA sequences that then lead to genetic disorders are located in exons. Therefore, sequencing of the exome is thought to be an efficient method of analyzing a patient's DNA to discover the genetic cause of diseases or disabilities.

This test sequences the exome nucleotide by nucleotide, to a depth of coverage necessary to build a consensus sequence with high accuracy. This consensus sequence is then compared to normal population standards and references, and the result is interpreted by board-certified laboratory directors and clinicians. By sequencing the exome of a patient and comparing it to normal reference sequence, variations in an individual's DNA sequence are identified and associated with medical conditions.
Indications for Testing
• Patients with an undiagnosed suspected genetic syndrome
Special Note
A complete Trio for the same biological family is required to interpret Sibling Trio results.

If a qualified variant is found by this test, RNA sequencing (RNAseq) can be performed to aid in the reclassification of the variant. A qualified variant meets our prediction algorithm criteria (SpliceAI) that RNAseq will provide additional functional information.

Select RNAseq at the time of order to reflex to RNAseq if a qualified variant is found by WES. RNAseq can only be performed on blood samples; if an additional sample is required to perform RNAseq, Client Services will reach out to the ordering provider.
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