Preconception Genetic Carrier Screening

Preconception genetic carrier screening is a blood test, and we are checking to see if you are a carrier of a single gene disorder. A good example of this is Cystic Fibrosis. This is where you have a mutation on chromosome seven that causes a certain gene to not function correctly. Having the CF mutation will likely have no clinical signs and symptoms. The reason why I say likely, just since we're off on CF, cystic fibrosis carriers who are men actually can have some clinical symptoms. This is something called CBAVD, congenital bilateral absence of vas deferens, and it can cause them to not have a vas deferens. The vas deferens connects the testes to the ejaculatory tract, essentially you’re shooting blanks and creating sperm of the testes, but it's not getting connected. In short, if you have actual cystic fibrosis, the cells that make mucus, sweat, digestive juice get messed up. The biggest players are going to be the lungs. Many people with CF need a lung transplant, get chronic pulmonary infections, and then the pancreas also can be an issue. So long term cystic fibrosis is really terrible. It has a short life expectancy, and getting a lung transplant sounds not great. That's an autosomal recessive condition.

So most things that you're getting tested for in genetic carrier screening are single gene disorders that are called autosomal recessive, meaning you need both of the genes, one from the egg source, one from the sperm source, and you have to inherit both of them to have the full fledged disease. Otherwise, you're just a carrier, and most of the time you're a silent carrier, and it gets passed in families and you do not know. So if you and your partner both carry CF, you have a 50% chance of having a child that is also a carrier, meaning they inherited one good chromosome from one person, one bad from the other. You have a 25% chance that your child's totally fine, they got the good from each person, and then you have a 25% chance you have a child that actually has the terrible disease. Now, CF is one of the most common ones, and that's because it's survivable. So many diseases are tested you've not even heard about because they're not and I've had patients whose babies die from them, and they're terrible. So if you're going into your OBGYN and you walk in and you say, hey, we want to get pregnant, I'm scheduling a preconception visit. Did you know that's a thing? It's fantastic. Your OB also loves this visit because it's too much to talk about in an annual. That's not the purpose of an annual. The purpose of an annual is for health related screening, pap smears, breast, mammogram, thyroid, general health. If you want to get pregnant, then a preconception visit allows them to talk about the questions you might have about what do I need to do when I get pregnant? How long is too long when it comes to TTC? All the stuff we talk about, but also the preconception blood work, which typically includes preconception genetic carrier screening your blood type check to see if you're immune to rubella and varicella. Those are both viruses that can cause birth defects if you get it for the first time and you're pregnant, and then sometimes blood levels like vitamin D. So preconception testing is awesome. If you don't get this done at your OB, we're going to talk about it. I recommend everybody do this one because it's a heck of a lot easier to know now than to go through the terrible process of losing a child. I've had patients who say that's not an option for us, but maybe we will adopt instead. Maybe we will not become parents. Maybe we'll use a sperm or egg donor to mitigate this risk. There's no right answer, but I live in the world of knowledge as power and you being able to make the choice, and maybe it's not. I have patients who don't have a deadly disease, but they have a congenital hearing loss, and they decided not to test this out, not to do IVF for this. However, they started taking sign language so that they would be able to communicate and be prepared no matter what happened. So knowledge is power.

Preconception genetic carrier screening is blood panel testing for you and your partner. You both should have it done officially. If you have it done and you carry zero things, then your partner doesn't have to. However, if you carry anything, they should get it done. If you are trying to get pregnant and using a sperm donor or an egg donor, then the other gamete source, egg or sperm should also be tested. This is a tricky one, because you then need to make sure the donor has been screened for anything that you are positive for, and they do not carry it. The reason why that's important is because we can now test you for almost 700 diseases. 10 years ago it was pretty standard to test for the big three which are cystic fibrosis, spinal muscular atrophy and fragile X. So your donor, depending on when they donated, could have been tested for three or 700 things. You actually have to look at the report and see if they were tested for what you have now you can run 700 gene panel because in a tube of your blood, you get so many cells, so it is now so much easier to run looking for these known mutations. Let's just imagine the blood test has these flags where these mutations are, and they're putting your cells through it to see what sticks. That's very oversimplified, but it's important, because it's not that way for embryos.