Monday, May 6, 2013

The genetics of CF

By now you have read our diagnosis story, but you may be asking how we didn't know that having a child with CF would be a possiblilty for us. Well it's easy to not know when no on in your family, that you have ever heard of, has been diagnosed with the disease. Zach was the first, and is still the only, known person (young or old) in our family with CF.
That just goes to show how rare of a disease this is. I suppose there could be other older family members with CF who were just never diagnosed. People who have been living with various other conditions or who died from respiratory complications and it was never thought that they could have CF.  I bet if we look in our family history we will find stories of babies who died of malnourishement or what was thought to be pneumonia when in fact it was CF. Until the 1950's there wasn't a name for this disease so it was not diagnosed. And even once they discovered what it was most patients with CF didn't live to attend elementary school (we will get to more statistics on another post).
So how prevalent is the CF gene?
That's approximately 1 in every 31 Americans!
Looking at my family: I have 2 siblings. Together we have 7 kids. 
My dad had 5 siblings, counting me and my siblings that makes (roughly) 17 cousins (I may be missing 1 or 2). Now most of us have kids. Now your looking at 45 second cousins. A couple of those have had  kids...I think there are 3 3rd cousins (that I know of). So that makes a total of about 71 just on my dads side of the family! 
You add to that my mother's side of the family. She has 3 brothers. My uncles have fathered 7 kids (that I know of). Of those cousins I only 1 has had 2 kids.
Now we are up to a total of 80 family members (and that's not going back further than my parents) Is it really possible I am the only carrier in my family??? Statistically speaking there should be at least 1 more. Yet, my boy is the only one with the disease and my daughter is the only carrier we know of.
Then looking at my husbands family: He has 2 siblings. Those 2 have a total of 3 (biological) kids.
His father has a sister. She has two children. They now have 3 kids. (husbands family is a lot easier to keep track of LOL)
His mother has no biological siblings.
Just going back this far it makes sense that he is the only known carrier (statistically speaking)
Now to get to the insane part. I mean how likely is it for a woman from NY and a man from FL, both not knowing they carry the CF gene, to meet, fall in love, get married and have kids??? I'm sure if I was better at math I could come up with some crazy equation to figure it out, but lets just say it's not a likely as you would think. Pure luck I suppose you could say. It gets better.
Once those 2 people meet, fall in love, get married and have kids there is only a 25% chance their kid will have CF. 25 PERCENT! A 1 in 4 chance. Talk about luck of the draw. Every time those parents get pregnant there will be a 1 in 4 chance they will end up with a CF kid.
Since Zach's diagnosis we have made sure that all our family members make sure to tell their doctors that there is a family history of CF when they are planning to have children. We still don't know of any other carriers in either of our families. It's crazy.

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