Health Information and Tools >  Exome sequencing: About this test

Main Content

Exome sequencing: About this test

Exome Sequencing

About this test

Exome sequencing is a test that can help to understand if certain health concerns have a genetic cause. From a simple blood test, exome sequencing can look at thousands of genes all at the same time.

What is a gene?

Genes are the instructions that tell your body how to develop and function. They are like a recipe for making cookies or the blueprints for a house.

You have 2 copies of almost every gene. One copy comes from the egg and one from the sperm that formed you. There are thousands of genes that are important for our health.

What is exome sequencing?

Exome sequencing looks for differences in a gene that may stop a gene from working properly and cause health concerns. These differences are called pathogenic (or disease-causing) variants.

Imagine your genetic instructions as a large library and your genes as books in the library. You have around 20,000 books in your genetic library. Exome sequencing reads through some of these books, looking for words that are misspelled, extra words, or words that are missing. Exome sequencing does not read through every single book in the genetic library. It only reads the books that are important for health and development.

Exome sequencing is usually done on a blood sample. In special circumstances, other samples, like a saliva (spit) sample, may be used. To help understand the results, family members such as biological parents may also be asked to give a sample.

There is no cost to you for this test. It may take several months to get the results. Ask your healthcare provider how you will get the results.

What type of results could I get?

  • Positive result (pathogenic variant): A positive result means that a genetic cause is found for the health concern. Sometimes, knowing the genetic cause of a health concern can lead to specific treatment or change how your medical team follows you. A positive result often does not change recommendations for your medical care that are already in place. In most cases, a positive result will also tell you how the health concern may be passed down in your family.
  • Negative or uninformative result (no variant detected): A negative or uninformative result means that the test did not find a genetic cause for the health concern. Exome sequencing does not look at all of your genes, so it is possible that there is a genetic cause that was not found by exome sequencing. Although our understanding of genetics is growing every day, there are limitations to what is known at this time.
  • Uncertain result (variant of uncertain significance): An uncertain result means that a genetic difference was found that is not well understood. It may or may not explain the health concern. If you have an uncertain result, your healthcare team will discuss possible next steps to try to better understand this result.

It is important to know that genetic testing using a sample from parents and a child may reveal if the child has a different biological father or mother. Let your healthcare team know if this is a possibility.

What are secondary findings?

If you decide to have exome sequencing, you also have the option to learn about secondary findings.

Secondary findings are results from a specific set of genes that are important for health but are not related to the main reason that exome sequencing was recommended by your healthcare team.

Differences in one of these genes may increase your chance of developing certain health concerns in the future. For example, secondary findings may show that you or your child has a higher chance of developing a certain type of inherited cancer or inherited heart problem. These are rare conditions.

Not everyone with a secondary finding will actually develop health concerns. Secondary finding results will not tell you if you will develop symptoms or at what age you could develop them. But secondary findings could lead to your healthcare provider recommending a new medicine, regular screening, or surgery. If you choose to learn about secondary findings and a secondary finding is found, your healthcare team will talk to you about recommended next steps.

People can have many different reactions when they learn about health concerns that they may develop later on. Sometimes people want this information. Other people may not want this information. Talk to your healthcare team about how this feels for you.

Every person who has exome sequencing needs to decide if they want to learn about secondary findings. For example, a parent will decide if they want to know secondary findings for their child and will also decide if they want to know their own secondary findings. Secondary findings will only be included in your or your child’s results with your consent. The decision of whether or not you choose to learn about secondary findings will not impact your ability to have exome sequencing.

What do my test results mean for life insurance?

Because genetic testing can tell you information about your health, it may bring up questions regarding life insurance. There is currently a law in Canada that provides some protection. For example, an application for life insurance should not ask about genetic results. However, the application may ask about medical conditions for you and for your close biological relatives.

To see this information online and learn more, visit


Related to Exome Sequencing

For 24/7 nurse advice and general health information call Health Link at 811.

Current as of: February 22, 2024

Author: Clinical and Metabolic Genetics Program, Alberta Health Services

This material is not a substitute for the advice of a qualified health professional. This material is intended for general information only and is provided on an "as is", "where is" basis. Although reasonable efforts were made to confirm the accuracy of the information, Alberta Health Services does not make any representation or warranty, express, implied or statutory, as to the accuracy, reliability, completeness, applicability or fitness for a particular purpose of such information. Alberta Health Services expressly disclaims all liability for the use of these materials, and for any claims, actions, demands or suits arising from such use.