Genetic Testing for Marfan Syndrome

Today’s post comes from a question from Tom:
How did you ensure you didn’t pass Marfan on to your child? Any good links/resources on that process?

This is a great question! First, I’ll briefly explain how Marfan works.

Marfan is what’s called an autosomal dominant disorder. This means that it is a single mutation that causes Marfan and if you have the mutation, you have Marfan, at least to some degree (there are mild cases to severe cases). You can’t be a carrier, like you could with something like cystic fibrosis. This also means that children have a 50/50 chance of inheriting Marfan from the affected parent. Marfan happens equally among men and women and across all races.

If you decide to have a baby the old fashioned way, there is no way to guarantee that your child won’t have Marfan. This is the option my husband and I decided on. It was just luck that Menininho doesn’t have Marfan. If we have another biological baby, s/he has the same 50% chance of having Marfan that he did.

If you want to try to be sure that your biological child doesn’t inherit Marfan, genetic testing may be an option. First, the affected parent must be tested. 90-95% of people who meet the clinical criteria for Marfan test are able to have their mutation identified. A negative test result doesn’t necessarily mean that you don’t have Marfan (although it could mean you have a related disorder instead, like Loeys-Dietz syndrome, MASS Phenotype, or a form of Ehlers-Danlos syndrome). Dr. Dietz, one of the world’s pre-eminent Marfan researchers, explained it to the teens at conference like this. We know that Marfan is caused by a change to FBN-1 (fibrillin). Right now, we know how to test FBN-1 itself. However, there are all kinds of proteins that may create changes to FBN-1 that we haven’t yet identified, and the 5-10% who clearly meet clinical criteria probably have mutations that just haven’t been discovered yet. Confusing, I know.

[Moral of the story: rely more on clinical criteria for a diagnosis and save genetic testing for 1) pregnancy issues and 2) when it’s hard to get a clear diagnosis .]

Aaaanway. So, you want the genetic test to locate your mutation. There are a few different labs that do the test, but I hear that all labs are not created equal. Tulane University’s Matrix DNA Diagnostics lab was the first in the country to do the FBN-1 test and is spoken highly of. I had my test done there 4 years ago. Click here to download their FBN-1 testing information. Many insurance companies are now covering this test, but if not, the initial test will cost $1400 (from Tulane). You can have your blood drawn anywhere and shipped overnight to Tulane. If you live in the US, it will take 5-6 weeks for you to get your results.

Once your mutation has been identified, you and your partner will need to find a center that does pre-implantation diagnosis in-vitro fertilization. Basically, the doctors will create embryos in the Petri dish and test them for the mutation that you have. [Each family shares the same mutation but manifestations of that mutation vary, meaning some family members might be mildly affected and others more severely affected.] If you’ve produced an embryo that doesn’t have Marfan (which is not a guarantee), one will be implanted in the uterus and if the implementation works, your child shouldn’t have Marfan.

If you’ve gone the old-fashioned route, you can still find out right away if your child has Marfan (providing you had the genetic test). You can test the baby in utero using amniocentesis, or you can wait till he’s born. We used Menininho’s cord blood and had the sample shipped to Tulane the same day he was born (needed to be the same lab where my test was done). When doing testing on other family members like this, the test is only $350 and results can be had in 2-3 weeks.

If you do not do genetic testing, it may take much longer to find out if your children are affected. It is my understanding that the aorta is not stable until 3 years of age so it may not be useful to do an echo prior to this point. A slip lamp eye exam should be done around 18 months of age so that any potential vision problems can be addressed so as not to interfere with physical development, like walking. Because Marfan is progressive, it may take years to know if children are affected. Routine echoes and eye exams are recommended to catch any problems early, since preventative medicine is best.

OK, I think that covers the bulk of it. I’m sure there are things I’m forgetting. Always feel free to post questions on this or other questions and I’ll help you find the answers! Further information on genetic testing and labs that will do the FBN-1 test can be found via the National Marfan Foundation. Amy Kaplan is their nurse and you can contact her at akaplan@marfan.org.

The opinions offered at Musings of a Marfan Mom are for informational purposes only and are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding Marfan syndrome and any medical condition. Never disregard professional medical advice or delay in seeking care because of something you have read here.

7 Comments

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7 responses to “Genetic Testing for Marfan Syndrome

  1. Great information. And I like the way it’s presented – in a non-judgemental manner. Genetic testing can be such a touchy issue sometimes.

  2. Interesting information! Great post, Maya.

  3. What an interesting blog. I look forward to reading and learning more! I saw your blog on SITS and decided to stop by to say, “hello”. It’s nice to “meet” you. I’m going to add your site to my “follow” list so I can keep up with your posts. Wishing you all the best in 2010.

    Kindest regards,
    Brook

  4. Here is a link with some additional information on the genetics of Marfan. It was prepared by our Genetic Counselor and also has links to some useful resources that may be helpful to others who are dealing with this condition. Thanks for helping to bring more attention to this terrible condition. http://www.accessdna.com/condition/Marfan_Syndrome/238.

  5. Leta Gribble

    I just found out I have a strong possibility of having marfan. Up until this point I was a runner, played volleyball, basketball, you name it. Now I kind of feel like a ticking timebomb until I get all my cario and pulmonary tests done. What do you do to exercise and have you already had to have surgery?

    • Hi Leta,
      The key to exercise is moderation. Many activities are ok if we do them in a mild to moderate manner. For instance, competitive basketball is out, but a casual pick up game might be OK, and definitely something like H-O-R-S-E. Swimming is one way that I stay in shape. It’s great on our joints. I also go for walks and use a stationary bike and treadmill at my apartment gym. Exercise is important, so you don’t want to give it up totally.

      If you’d like, I can do a post on exercising with Marfan!

  6. Olive Ng

    Thank you for the information, may i ask, with the age of 30yo, with skeletal complications symptoms positive, unknown eye and cargio complications or symptoms. Is it possible of having marfan, should i do the genetic testing to confirm the diagnosis? Is it possible the symptoms appear so late…???

    From Ng

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