Consider whole exome sequencing (WES) when a patient’s personal medical history and physical examination findings strongly suggest that there is an underlying genetic cause but no clear clinical diagnosis.
This test could also provide a more cost effective method of obtaining a diagnosis when there is a broad differential diagnosis that might otherwise require multiple genetic tests to rule out or confirm a diagnosis.
Currently, there are about 20,000-25,000 genes in the human genome. Our genes are made up of exons, the portions of the genes that are expressed, and introns, the portions of the genes in between the exons. Relatively little is known about the introns.
It is believed that the large majority of mutations that lead to genetic disorders occur in the exons. WES is therefore considered to be a comprehensive and effective means of investigating the cause of genetic disease. With our current technology, WES is able to determine the genetic cause of a condition of approximately 30% of individuals who seek testing.
What type of sample is used?
A blood sample will be needed to perform this test.
Why are parental samples requested?
When WES is ordered we request samples from the patient’s mother and father. We try to obtain samples from the parents for comparison with the patient’s sample to help interpret the patient’s result. We do not perform complete whole exome sequencing on the parental samples.
Rather, we test for specific changes in the gene(s) that are identified in the patient when further data is needed to interpret the significance of the genetic change. Samples from parents are NOT required but can offer useful information for interpreting the patient’s result.
We do NOT issue separate results for parents. If a parent’s sample is tested then their result may be noted on the patient’s report. It is up to the patient to share the information with their parent at the patient’s discretion.
What information is included in a WES report?
There are four main categories of results:
- Mutations and variants of unknown significance suspected to be associated with the patient’s clinical phenotype
- Variants associated with medically actionable conditions
- Carrier status for autosomal recessive conditions that are recommended by ACMG or ACOG for reproductive carrier screening
- Pharmacogentic information regarding how the body metabolizes certain medications
The last three categories are optional, meaning patients can decide if they wish to receive these results or not. There is no additional charge to receive all four categories of information and no additional turn-around-time for results if all four types of information are requested.
What is the adult screening exome?
The adult screening exome provides information about a patient’s risk to develop medically actionable conditions and information about their body processes certain medications. It can also provide information about conditions that they can pass on to their children.
This information has the potential to guide management and even to prevent certain conditions. Healthy individuals might consider this testing to better understand and reduce their risk for future health problems.
How long does it take to get results?
Exome results are available approximately 4-5 months after testing.