Where Does Cystic Fibrosis Come From?

So, what exactly is the cause of Cystic Fibrosis?

Well, let’s have a little lesson on genetic inheritance!

Cystic Fibrosis is a recessive trait. When a trait is recessive, as opposed to dominant, the trait will express itself in a person if only recessive genes are present—there can be no dominant genes in their DNA for that trait. If a person has a dominant gene, the dominant trait will be expressed in that person. (We can remember that by thinking of “dominant species” being the stronger one or a person who “dominates” is the one that is most expressive.)

Because Cystic Fibrosis is on one of the autosomal chromosomes, rather than a sex chromosome, both males and females are equally likely to be affected by the disease. This also means that both genes (one will come from the mother and the other from the father) must be recessive to express the trait of Cystic Fibrosis. If both parents have a recessive gene, they can each pass their recessive gene on to their child. This does not mean that a child with Cystic Fibrosis has to have two parents with the disease, though. Remember dominant genes? The dominant trait is to not have Cystic Fibrosis. If the parents have the dominant gene for not having Cystic Fibrosis, that dominant gene will, well, dominate and “cover up” the recessive gene. This is called “carrying” a disease—when a person has both a dominant gene and a recessive gene, only expressing the dominant trait but having the potential to pass down the recessive gene to any children. If one or both parents do not carry the disease, meaning both of their genes are dominant, none of the children will be able to have the disease.

Making sense? I will map out this inheritance pattern to further illustrate what causes a person to inherit Cystic Fibrosis. We do this using a Punnett Square, which is a tool to show each genotype (genetic make-up) that is a possible result when two genotypes (genetic make-ups of parents) are crossed.

Dominant genes are represented with a capitol letter and recessive genes are represented with a lowercase letter. Because we are talking about CF today, I will use the letter F and f. I’ll use F rather than C because generally letters would be used that can’t be confused between capitol and lowercase letters (using N and n rather than U and u, for example).

Let’s first see what happens when two parents carry the disease (remember this means that one gene is recessive, meaning they can pass that on to their children, and the other is dominant, meaning they do not express the disease). Each parent would then give each child exactly one of their genes—in this case, either the dominant or the recessive gene. We place the parents on the outside of the box then create a row or column to each gene—so two rows for the two maternal (from mom) genes and two columns for the two paternal (from dad) genes.

	F	f
F	FF	Ff
f	Ff	ff

This shows that two parents who carry the disease (one capitol letter/dominant gene and one lower case letter/ recessive gene) can have children who either have two dominant genes (FF) meaning they do not express the disease nor do they carry it, children who have a dominant and a recessive gene (Ff) meaning they do not express the gene but they do carry it, or children who have two recessive genes (ff) meaning they do express the gene because there is no dominant trait to cover up the recessive trait. Statistically, this means 3/4 of their children will not express the disease and 1/4 of their children will express the disease.

What if we cross a person who carries CF with a person who does not have or carry CF?

	F	F
F	FF	FF
f	Ff	Ff

This shows that their children will either have one dominant and one recessive gene (Ff) or have two dominant genes (FF). None of their children will have the disease because the parent with two dominant genes will not pass on any recessive genes to build a person who has only recessive genes present. This will happen with any couple where one had two dominant genes because that parent with two dominant genes cannot pass down the necessary second recessive gene to cause CF in their child. (BTW: this is called being homozygous, when both genes are the same—either FF or ff. When they are different—Ff—this is called being heterozygous.)

What other combinations can we think of? Ff and Ff, FF and Ff have been shown already. Other combinations are ff and Ff (a person with the disease and a person who carries the disease), ff and FF (a person who has the disease and a person who does not carry or have the disease), or ff and ff (two people with the disease). Here’s what those would look like:

	F	f
f	Ff	ff
f	Ff	ff

	F	F
F	Ff	Ff
f	Ff	Ff

	f	f
f	ff	ff
f	ff	ff

The inheritance of Cystic Fibrosis is therefore only possible to pass down if BOTH parents either have the disease or carry it.

Recessive Inheritance Pattern

In my case, both of my parents carried the disease. The recessive genes had been hiding in my mother and father’s lineage well enough that we had never heard of Cystic Fibrosis before I was diagnosed. This can happen with Cystic Fibrosis and any other recessive genetic disease because of its ability to hide behind the dominant gene.

If you are concerned about recessive genetic illnesses, especially if any are present in your families, you and your spouse could consider genetic counseling before having children. We should remember, though, that a child is not defined by any disease that they may or may not have in their lives any more than they are defined by the color of their hair or shape of their eyes.

Keep Hope,

-Cystic Sister @----

My Diagnosis

I am one of the 30,000 Americans, 20,000 Europeans, 3,000 Canadian, and any others who has Cystic Fibrosis. My parents are two of the 1 in 20 people who carry the disease without exhibiting any symptoms. Odds of 1 in 4 worked with the cosmos to give me the opportunity of having Cystic Fibrosis. But this wasn’t something I have always known or something my parents had always imagined happening. My diagnosis was a little more surprising than normal…

It was just before Easter in 1999 when I woke up in distress. Using my sister as messenger, I sent for my mom who was just down the hall. When my mom came into the room asking what the matter was, I uttered four words that no five-year-old makes up…

“Mommy, I can’t breathe.”

Of course, a rush to the hospital to see what could possibly be wrong was in order. Upon admittance, X-rays were ordered and the results weren’t the best.

I had atelectasis, or a partially collapsed lung. Mucus had plugged up parts of my airway, completely blocking air movement to the lower lobe of my right lung. I was put on IVs and oxygen tubes in my nose. They used percussion therapy (turning me at an angle that forces my head to look more towards the ground and thumping on my back to loosen the junk in my lungs) and breathing treatments to try to fix it. But my oxygen saturation levels stayed put and I was stuck for about nine days. Easter came and went (turns out the Easter Bunny knows when children are in the hospital!), and I was missing a good chunk of Kindergarten. To make matters worse, the oxygen tubes in my nose were uncomfortable. I wasn’t one to frequently blow my nose, but that was my excuse for removing the tubes inserted in my nostrils. It was working as a good cover up, too, until I fell asleep “blowing my nose” with the tubes at my chin, flowing oxygen into my mouth.

You can imagine my mother’s surprise when my oxygen saturation jumped. She called a nurse and so the calamity began. Not only was my lung blocked up, my sinuses were 100% blocked as well. According the CT scans, there was literally no air flow in my nose. Plans to discharge me from the hospital and set a date for sinus surgery were made.

Before surgery, questions needed to be answered. Do I have certain health concerns, what did my family history look like, etc. One question was about Cystic Fibrosis. My mom looked at the doctor like he was crazy, I’m sure. “No, I’ve never even heard of that.” Well, apparently she should have. After looking at my history of frequent lung and sinus infections, a sweat test was ordered. Sitting in the hospital lobby wrapped up in blankets and sweats, I patiently waited until enough sweat had collected on my arm to give doctors all the information that they needed.

Doctors are never satisfied, I’ve decided.

The sweat test proved positive, but a stool sample was less decisive. My doctor was completely baffled; cases like mine aren’t typical. What do you do with a five year old girl who fits many of the symptoms, a positive test, and a negative test? Apparently the answer to that riddle was a blood test.

Yes, they checked my blood for vitamin levels and the genetic information to find the positive or negative for Cystic Fibrosis.

To this day, I’m not really sure why they didn’t just start with taking my blood, but I guess doctors just like to experiment with situations like this. Maybe it makes their job more fun. If I was a doctor, I might ask people if I could test something just so I could look at them, make that “huh…” face that scares patients so often, then request the test that could give us real evidence. It’s like playing with bubble wrap, popping just a few to start off with almost convincing the bubble wrap it can survive…then laying it on the floor and rolling all over it.

The conclusion was a definite positive. I had Cystic Fibrosis. Finally sinus surgery could be scheduled and changes could be made.

First, I had to be introduced to the Cystic Fibrosis clinic. Lynn the head nurse, James Harris the doctor, and the respiratory therapist whose name I never knew because we called her the “blow blow blow blow lady.” Lynn always stopped by and asked me how I was doing and made sure to find a way to make me smile. Dr. Harris always told me about how much I’d grown and marveled at my amazing case. My respiratory therapist was probably the reason I tolerated anything else; she would come to take me to another room, hand me a tube to place in my mouth for the pulmonary function test, have me take a couple normal breaths, then would shout “Suck in deep!...and blow blow blow blow blow blow blow blow blow blow blow blow! Now suck in deep!” Her encouragement always pushed me to get great results. They eventually became my support group that I got to see 3-4 times a year. I knew what to expect every time I went in and I always got that impressed look from my doctors and nurses.

Now I’m out at college, my first time really away from home for more than a weekend or so. When I come back, the respiratory therapist will have officially retired, I’ll be moving to the adult clinic and saying goodbye to Dr. Harris, and I will be able to tell them that I was taught well by Lynn. Now I stand as a reminder that attitude is everything and encourage awareness within my friends, classes, and family.

The diagnosis isn’t easy; at first I resisted. I would throw fits, deny everything, and refuse to let my mom tell a soul. My mom had a hard time figuring out how to handle the news, herself. A new lifestyle isn’t just mine; I got to take my family on my journey with me. Now, this is how I direct my energy. I’ve learned to take what I have and turn it into something to learn from. Cystic Fibrosis does not define me, I define me. I define who I am through this experience and any other experience I have the opportunity to go through. To those of you who need it, there are support groups out there. Ask your CF specialist about them and talk to your friends and family. 


Just remember, you aren’t alone and you have the power over this, no matter what. Those of you who know someone who is affected, they may just need someone to talk to sometimes, someone to remind them to take care of themselves. Having someone means more than anything. Happy people stay healthier better. Never give up. You have friends, family, peers, specialists, and sixty-five roses going for you.

Keep Hope,

Cystic Sister @----

Introductions

Once upon a time in a land far from home lived a girl...

Now, this girl was not a princess. She wasn't a peasant with a secret love affair with a prince. She wasn't even an evil stepmother. She was just a girl attending college. But this girl had a special reason for being proud of her situation.

You see, this girl has Cystic Fibrosis. Most people with Cystic Fibrosis have trouble being away from home in a new climate by themselves. Keeping track of lung function, appetite, weight gain/loss, sinus pressure and infection as well as college work isn’t easy by anyone’s standards.

Well, one day this girl decided to start a blog for awareness of her disease. The more she thought about it, the more she seemed to want to do it. She really believed she could change the world—raise awareness until a cure was found and when the inventor of the cure was accepting prizes, money, and fame, they would point to her and say, “I couldn’t have done it without the awareness raised by that girl!” The crowd would go wild and thousands of people with Cystic Fibrosis would ask for her autograph. They’d put her on billboards and talk shows and eventually she would become the face of Cystic Fibrosis, a poster child before graduating college.

…

Well, okay, maybe that wouldn’t happen, but awareness is always a good thing on such sensitive subjects. As is customary, I believe an introduction is at hand here.

Myself in the hospital, October 2009

That girl in the story was, of course, me. I am currently living in Idaho attending my second semester of college. I have known about having Cystic Fibrosis for 12 years now. I was diagnosed at about 6 years old, so for those of you who like numbers, I have known for 2/3 of my life now. I have a very mild case and it doesn’t seem fair to me that I have it so easy, but I do deal with some of the challenges. I don’t like to focus on that, though. I like to think of the positive parts, such as using CF as the topic for projects and papers in high school and college or inspiring others to do the same. I like to spread the word, not the hurt, so this is going to be exactly what the doctor ordered. (Not literally. I may not be as good at the doctor’s orders as I like to think I am…)

My goal is to raise awareness about Cystic Fibrosis. I really believe if more people are aware and more people are willing to help in every way they can, that we can make the lives of those dealing with the disease easier as well as eventually find a cure for the disease. That is my purpose as the girl with Cystic Fibrosis.

Keep Hope,

Cystic Sister @----