By Guest Blogger Stephany Foster, Recombine
Your genes encode the instructions for all parts of your body to grow and function. Changes in your genes, called mutations, can disrupt those instructions and may lead to genetic disease.
Carrier screening allows you to learn about what changes you carry in your genes and what risk you and your partner have of passing those mutations on to a future baby. Whether you’re thinking about starting a family now or in the future, learning about your genes can help you make decisions about your health and that of your future family.
Carrier screening takes a look at your and your partner’s genes, by way of a blood or saliva sample, in search of mutations that can lead to genetic disease. Most of the diseases screened for are autosomal recessive, meaning that both parents must be carriers in order to have a 25% chance of having an affected child. Carrier screening panels also include X-linked diseases. In this case, the biological mother’s carrier status is important. If the mother carries an X-linked disease, there is a 50% chance of having an affected son. Knowing your carrier status helps us identify your risk and should be followed by a conversation about your results with a genetic counselor to determine any next steps.
The technology used for carrier screening has evolved quickly. The newest technology, called sequencing, looks throughout your genes for both common and rare disease-causing changes in your DNA, providing the most comprehensive assessment of your carrier status. Sequencing provides high detection rates (in other words, it’s good at finding disease-causing mutations) and thus low residual risks (the chance that you could still be a carrier after a negative test); results usually take a few weeks.
For those looking for a quicker, lower cost option, genotyping is also available. This technology specifically looks for common mutations in your genes but would miss any rarer mutations that it’s not targeting. While genotyping can provide high detection rates for some diseases, it doesn’t always do so for all genes and may differ based on your ethnicity; this means that residual risks may not be as low as when sequencing is ordered. However, genotyping results are usually ready in 1-2 weeks and the test will typically cost a little less.
Given its comprehensive approach, your doctor may recommend sequencing, but you can always discuss both offerings with your doctor as well as a genetic counselor to decide which test is best for you. Please find more information on carrier screening, here.