So, what is Genetic Carrier Screening?

Genetic carrier screening is a blood or saliva test, which allows us to check your DNA to see if you’re a carrier for certain genetic conditions.

There are two levels of carrier screening:

  • Three-gene test – This test covers Cystic Fibrosis (CF), Spinal Muscular Atrophy (SMA), and Fragile X Syndrome (FXS). This test is fully covered by Medicare.
  • Expanded Panel tests – These tests look at the CF, SMA, and FXS genes, as well as hundreds of genes for other inheritable conditions. Testing for these additional genes is not covered by Medicare and is recommended on a case-by-case basis. It is best discussed with your GP or genetic counsellor.

Why is it important?

Being a genetic carrier of a condition generally means you carry one “faulty” gene (and one normal gene) for a condition. Carrying one “faulty” gene doesn’t typically cause symptoms of the disease or affect your health- you need two “faulty” genes for that. However, when you have a baby, you have a 50% chance of passing your faulty gene on to them, and if it turns out your partner also has a matching “faulty” gene, there is a 1 in 4 chance that your baby will end up with two faulty genes and, hence, have the condition.

But what are the chances?

CF, SMA, and FXS are the three most common inheritable diseases that impact pediatric life expectancy. Approximately 1 in 20 Australians are carriers for at least one of these conditions, which means that about one in 240 couples will both be carriers and have a 1 in 4 chance of having a baby with the condition.

Do I have to do it?

Not at all – the most important thing is to know what it is and to have a discussion with your partner about whether it is right for you. As with any test, it’s important to understand the pros, cons, and limitations of any test, as well as what it means if the test comes back positive. I do recommend carrier screening to all of my patients, but I make sure we have a thorough discussion about these aspects before we proceed.

When?

Ideally, genetic carrier screening should be discussed three or more months before trying to conceive. However, it can be done at any time, including during pregnancy, but thorough pretest counseling is crucial in this situation.

I’ll do a post in a little while to discuss your options if genetic screening results indicate that you and your partner are both carriers… stay tuned.