Downloadable Patient Explainers

Almost all of us carry a few non-working genes for rare genetic conditions without ever knowing it. Carriers are healthy, usually with no symptoms and nothing in the family history to hint at it. The chance of having a child with a serious genetic condition rises when both partners happen to carry a non-working copy of the same gene, or when a female partner carries an X-linked genetic condition. Expanded carrier testing lets you and your partner find this out before starting a family (or early in pregnancy), while your options are open. GeneScreen helps you understand your risk from the comfort of home, with a board-certified genetic counsellor beside you from start to finish.

Expanded Carrier Screening (ECS) looks at your DNA to see if you are a carrier of any non-working genes associated with recessive genetic conditions. Being a carrier is not the same as having the condition - most carriers would have no signs or symptoms. However, if your partner is also a carrier of the same non-working gene, you will have an increased chance to have a child with a genetic condition.

You may be offered both Expanded Carrier Screening (ECS) and Non-Invasive Prenatal Testing (NIPT) during pregnancy or before conceiving. They are both genetic tests but they are asking completely different questions about your pregnancy. Understanding the difference helps you make sense of your results.

A carrier has one working copy and one nonworking copy of a specific gene (also called a pathogenic variant). The working copy does its job and can make up for the non-working copy of the gene. Usually being a carrier would not cause symptoms in any way. In rare cases, some carriersmay experience mild effects.

Everyone carries genetic changes (pathogenic variants) in their genes. Most people are carriers for several conditions, and being a carrier does not typically affect your own health.  When both partners carry a change in the same gene, each pregnancy has a chance of the condition being inherited, commonly 1 in 4 for recessive conditions.

Women who are carriers of an X-linked condition have a non-working gene (pathogenic variant) on one of their two X chromosomes. Their second X chromosome has a working copy of that same gene. In most cases, the working copy compensates for the non-working one, so carriers don't show signs of the condition themselves. Some carriers do experience mild symptoms. Men only have one X chromosome in every cell (paired with a Y chromosome). So if a man has a non-working gene on their X chromosome, they would have the condition as they don’t have a second X to protect them. This means a man either has the condition or he doesn't, there's no in-between "carrier" state for them.