Overview

All of our genes come in pairs. We get a copy from each parent. Genes help determine everything from our eye colour to our height. We can also inherit gene changes. Gene changes can increase our risk for getting diseases like cancer. Or we can inherit gene changes that cause genetic diseases. These may include conditions like cystic fibrosis or sickle cell anemia. To have certain genetic conditions, you must get a copy of the changed gene from each parent.

Some genetic conditions are more common in certain ethnic groups. A screening test can be done to see if you are a carrier for the condition tested. A carrier is a person who has a gene change but is not affected by the condition. A carrier has an increased chance of having an affected child if their partner is also a carrier of the same condition. Testing often involves checking your DNA in a sample of your blood or saliva.

The results of genetic screening can help you make choices about having children. If you test positive, your partner should usually be tested too.

Which conditions can this test find?

Depending on your background, you can be tested to see if you or your partner might pass down gene changes to your child. You may be tested for:

• Inherited anemias. This group of conditions affects red blood cells. It includes sickle cell anemia and thalassemia. Sickle cell disease occurs most often in people of African background. Thalassemia occurs most often in those of Asian, African, or Mediterranean background.
• Cystic fibrosis. This is much more common in people who have family origins from the Quebec regions of Saguenay Lac-St-Jean and Charlevoix region.
• Tay-Sachs disease. This is more common in people of Ashkenazi Jewish backgrounds and people who have family origins from the Quebec regions of Saguenay Lac-St-Jean and Charlevoix region.
• Diseases that occur more often in people of Ashkenazi Jewish backgrounds. These include Tay-Sachs, Canavan disease, familial dysautonomia, and others.

Should you be tested?

If you think you might be the carrier of a genetic condition that you could pass along to your child, you may want to think about having genetic testing. Seeing a genetic counsellor may also help. They can explain what is involved.

Certain conditions are more common in some ethnic groups, such as those listed above. Some close-knit religious communities also have higher rates of certain conditions.

People with a family history of one of these conditions also may want to think about testing. You may want to have carrier screening and counselling before you have a child. The tests will help you understand the risks as well as your options. Speak with your doctor about whether this type of testing is available in your area.

What should you think about when deciding about this test?

• Your doctor may have you talk to a genetic counsellor. The counsellor can help you understand the test. You'll learn what the results could mean.
• Testing is not 100% accurate. But if you are in one of the higher-risk ethnic groups, testing is more accurate for certain diseases.
• You may choose to have testing if you are pregnant or considering a pregnancy in the near future. The genetic information may affect prenatal testing available during a pregnancy, whether or not a couple chooses to continue a pregnancy, and will often help parents make choices about the care of a newborn child.
• If you are planning to become pregnant, it is best to consider genetic testing before you are pregnant.