One's Chance of Having CF

A lot of people have a hard time understanding how someone can be born with cystic fibrosis, i.e. born with two gene mutations that cause one to have CF. I will do my best to explain...

There are three categories people fall under: 1)You do not carry a gene mutation 2)You carry one gene mutation, "carrier" or 3)You carry two gene mutations and have cystic fibrosis.

Let's go through a couple of different scenarios:

If a couple is going to have a baby, and neither of them carry a gene mutation, their baby has a 0% chance of having cystic fibrosis.

If one person is a carrier of one gene mutation and the other is not, their baby has a 50% chance of becoming a carrier of one gene mutation and a 0% chance of having cystic fibrosis.

If both people are carriers, their baby has a 25% chance of getting cystic fibrosis, a 50% chance of being a carrier, and a 25% chance of neither being a carrier nor having CF.

So, in order for a child to get the disease, both parents have to carry a gene mutation. Levi is a carrier of the G551D mutation, and I am a carrier of the deltaF508 mutation. Somehow, along the way, these mutations have been passed down from generation to generation, sight unseen. By chance, Levi and I fell in love, had a baby, and we both just happened to be carriers, which Ellis inherited from us. Cystic fibrosis is labeled as a "European disease", and 1 in 30 Caucasians are carriers, but this does not rule out other ethnicity's. Levi is Hispanic/Italian/Irish, and I am Lebanese/Italian/German/Irish.

The take away here is, if you plan on starting a family, it is extremely important to get tested for the cystic fibrosis gene mutations, especially if there is any family history or if you are of Caucasian decent. CF can be avoided if you take the steps to rule it out. This is something that can skip many generations and appear in someone like Ellis.

Please let me know if you have any questions or need for clarification!