Possible results and their implications

This result means that you do not carry the defective gene associated with any of the screened disorders. You therefore do not need any particular medical follow-up.

The “not a carrier” result is more than 99% reliable. Even if a person receives a “not a carrier” result, there is still a minimal chance that they carry a defective gene for one of the screened disorders. In fact, it is still impossible to say that the “not a carrier” result is 100% reliable because the tests detect only the most common defects in the population.

This result means that you carry a defective gene associated with any one of the screened disorders. However, you do not have the disorder associated with the defective gene and you will not contract it in the future.

If you are found to be a carrier:

• Your partner becomes eligible for the offer of carrier screening tests even if they were not initially eligible.
• Some members of your family also have a greater chance of being carriers. This applies to:
  • your children
  • your brothers and sisters
  • your cousins

If these people want children, it is best to inform them of your carrier status so that they can decide whether or not to get tested.

• Only one partner carries a defective gene
  If only one partner carries a defective gene, this couple has a very low chance of having a child with the disorder associated with this gene. Neither one of the partners therefore needs any particular medical follow-up.
• Both partners are carriers of the same defective gene
  When both partners carry the same defective gene and decide to have a child, the possible results for each pregnancy are presented below.
  • a 1 in 4 (25%)chance of having a child with the disorder
  • a 2 in 4 (50%) chance of having a child who carries the defective gene for this disorder, but who does not have the disorder
  • a 1 in 4 (25%) chance of having a child who does not have the disorder, and who does not carry the defective gene

These probabilities are the same for all the screened disorders.

For further details about the characteristics of carriers and the chances of giving birth to a child who is a carrier or who has a recessive genetic disorder, see the page Transmission of a recessive genetic disorder.

If both you and your partner are found to carry the same defective gene, you can receive genetic counselling to discuss the different family planning options and to get support for this decision process. Details about genetic counselling will be provided to you in the letter that you will receive with your test result and by the health professional who will phone you.

If both you and your partner are found to carry the same defective gene, here are the family planning options available to you:

• You can decide to have a child and to have a prenatal diagnostic test to see if the baby has the disorder. A prenatal diagnostic test is performed at the start of pregnancy through one of the following methods:
  • chorionic villus sampling (between weeks 11 and 13 of pregnancy). This method involves taking a small sample of the placenta either through the abdomen or through the cervix. Analysis of the placenta helps determine if the baby has one of the screened disorders.
• amniocentesis (as of week 15 of the pregnancy). This method involves inserting a fine needle into the pregnant woman’s abdomen to draw a small amount of amniotic fluid. Analysis of the amniotic fluid helps determine if the baby has one of the screened disorders.

These methods are used to determine whether or not the baby has one of the screened disorders, but they do carry a slight risk of complications.

If the baby has one of the screened disorders (1 in 4, or 25% chance), you can decide to continue with the pregnancy or to terminate it.

• You can decide to have the child without getting a prenatal diagnostic test.
• You can decide to use assisted reproduction services or to adopt a child.
• You can decide not to have any children at all or not to have any more children.

Each of these options is valid. Making a decision can be difficult. This decision can vary from couple to couple, depending on each partner’s values and principles. It can also vary from one pregnancy to another. Some options can be very expensive, such as assisted reproduction services and adoption. Some couples may simply be unable to afford them. You can discuss each of these options in your genetic counselling sessions.