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CF Gene Mutations and Nathan's Diagnosis

Posted Sep 03 2009 11:17am
I had been working on a few posts to recap the beginnings of Nathan and our journey as a family with Cystic Fibrosis in our lives.

I left off here with Nathan's birth story and am going to concentrate on Nathan's diagnosis with Cystic Fibrosis which occurred during his first month of life.

I am going to begin though during my pregnancy when my husband and I discovered we were carriers of the mutated Cystic Fibrosis gene. I remember very clearly the moment I found out, I was in the middle of teaching my first period seventh grade science class when someone from the main office came to cover me while I took a phone call from my OB/GYN.

Dr. N: "Christina, your bloodwork shows that you are a carrier of Cystic Fibrosis."
Me: "Um, so what do I do about that?"
Dr. N: "Your husband needs to be tested. Please come pick up the paperwork for the lab this afternoon."
Me: "Ok, thank you so much"

Thank you for what? Wait, what is Cystic Fibrosis? Thank you Dr. N for telling me that my unborn child may be born with a life shortening genetic disease.

My husband was tested and I prayed that he was not a carrier. I mean what are the odds of that happening, CF gene mutations can't be that common. Wrong, "the altered CF gene is not unusual. In fact it is quite common, occurring in about one in every 25 white people in North America" (Orenstein, David M., Cystic Fibrosis 3rd Edition: A Guide for Patient and Family, New York: Lippincott Williams & Wilkins, p. 216).

So, my husband was tested and shortly thereafter I received another phone call informing me that we were both carriers and needed to schedule an appointment for genetic counseling. Sick with the flu in the dead of winter, I accompanied my husband to the genetic counselor at the hospital where Nathan's CF clinic is currently located. The genetic counselor gave us a lesson in genetics (good thing since I am a science teacher and all) and explained our options of prenatal testing. I could have had a chorionic villus sampling immediately or an amniocentesis in a few weeks.

So here my husband and I ask the question, "What would be the benefit of testing and are there any risks?" The benefit is knowing and there are risks. Nothing can be changed though since there is still no cure for Cystic Fibrosis. "Many families have used these new methods to decide to continue a pregnancy if the fetus is shown not to have CF, or to stop the pregnancy (with an abortion) if the fetus has CF".

We did not undergo prenatal testing because abortion was not an option for us and we did not want to risk losing our baby. I would reconsider testing in the future (not for terminating) because diagnosing Nathan after he was born was a nightmare. I will explain.

Three days after Nathan was born we visited his pediatrician for his first routine visit. Dr. S informed us that we needed to bring him back to the hospital to repeat the foot prick test. No explanation why, only that it needed to be repeated. This test revealed that he had one of the Cystic Fibrosis gene mutations, my husband's Delta F508 (∆F508).

We were know scheduled at a different hospital for a sweat test. This is a test where sweat is collected and is analyzed for it's salt (sodium and chloride concentration). People with CF have higher salt concentrations in there sweat. Don't believe me? Just take a lick of Nathan and you will. Kidding, but seriously he is one salty little boy.

Nathan had his first sweat test when he was less than 2 weeks old and his second a few days later. Both sweat tests were inconclusive because he did not produce enough sweat to be analyzed.
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During the test, his arm was cleaned to remove any salt on the skin. Then a subtance (pilocarpine) is placed against the skin and with the help of slight electrical current can activate sweat glands. After a several minutes the electrodes were removed and a coiled tube was applied to collect the sweat. We waited for about an hour allowing Nathan plenty of time to sweat on two separate occasions but he still did not sweat enough.

When the Dr. A recommended we try a third time I spoke up. Everyone was becoming concerned that Nathan's weight was dropping below the 5th percentile and here we are waiting for him to sweat enough to find out if he had CF.

I recommended testing his blood for the millionth time. The response was that it can take up to four weeks to get the results from Ambrey Genetics since there were so many different mutations that needed to be tested. Again I spoke up. It took two days to find out I had the CF mutation 711+1G→T and two days to find out that my husband had mutation ∆F508 so why should it take four weeks to find out if Nathan had both of our mutations. Hm, that's a concept, why not just test to see if those two genes were present?

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So Nathan had his blood test which was a horrible memory in and of itself but a few days later (September 29, 2008) I was called in for the results. Nathan had both of our mutations meaning that he had Cystic Fibrosis. He was prescribed digestive enzymes immediately to help him digest and absorb the nutrients in his food (so that he could gain weight). My husband and I meet with Nathan's CF team two days later, got a compressor, were taught how to perform chest percussions (CPT), and just felt completely overwhelmed.

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And for Marcy over at Lovin Lane, I found this page in one of my Cystic Fibrosis reference books (sited above). It shows some of the more common CF mutations and some of their characteristics.

cf gene mutations

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