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Genetic Carrier Testing

What is a carrier test?

This usually refers to a genetic test that is used to find out if an individual has one copy of a disorder-causing gene. For certain disorders, carrier testing can be performed using biochemical tests that measure enzyme levels in the blood rather than test the genetic material.

The term ‘carrier’ is primarily used in the context of recessive disordersRecessive disorders require both parents to carry a specific disorder-related mutation and pass it onto their child for the disorder to be inherited.. Carriers of recessive disorders may pass a genetic condition on to their children even though they themselves are unaffected.

Even when there is no family history, carrier testing for recessive disorders is important for ‘at risk’ populations because these disorders, by nature, often do not manifest for many generations.

What does carrier testing involve and how can it be arranged?

Testing usually involves taking a simple blood sample. With genetic carrier testing, also known as molecular testing, genetic material is extracted from the blood for analysis. With biochemical carrier testing, enzyme levels in the blood are measured to assess whether or not a person is a carrier.

Carrier testing can be performed at any time but is generally targeted at people of reproductive age. Testing can be done during pregnancy but is preferable prior to conception so that couples can identify the risk in advance and have the widest range of options available to them for family planning.

For Tay-Sachs disease, there are a number of routes through which carrier testing can be arranged. Please see the Tay-Sachs carrier screening section for details.

Information about carrier testing for other genetic conditions that are relatively more common among people of Jewish ancestry can be found in the section carrier testing for other JGDs.

Things to consider prior to having carrier testing

When considering carrier testing, it is good to have an understanding of what the test is assessing and what the results may mean for you.  Please refer to our frequently asked questions section that answers common questions relating to carrier testing for Tay-Sachs disease and other serious Jewish genetic disorders.

It is beneficial to see a genetic counsellor prior to having a carrier test but not always necessary. If you have a family history of the condition that you are going to be tested for, then it is advisable to speak to a genetic counsellor first.

If you, and particularly if both you and your partner, are found to be carriers, it is important that you have the opportunity to meet with a genetic counsellor after getting the results to discuss the implications and the options available for family planning. Further details about genetic counselling and how it can be accessed is available in the genetic counselling section.

The information for carriers section offers more information about the significance of being a carrier, and options available to couples where both partners are found to be carriers.