CF 101: Diagnosis

For those of you unfamiliar with Cystic Fibrosis, those find that you know some things but not much, and even those who know a lot but would like a refresher, this post is for you. These posts will expand on information covered in the “Cystic Fibrosis” page linked above.

What is CF?

Cystic Fibrosis is a chronic, progressive disease caused by a faulty gene. Put simply, the malfunctioning gene – now called the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene – affects how salt and water pass through cells, causing thick, sticky mucous just about everywhere in the body. The two parts of the body most affected are the Lungs and the Digestive system (starting with the Pancreas), but CF often affects the liver, kidneys, endocrine system and reproductive system (98% of men with CF are sterile), etc.

Who gets CF?

Cystic Fibrosis happens when a person/child receives a defective (mutated) copy of a gene from each parent.

This diagram explains how recessive genes work.

This diagram explains how recessive genes work.

We all carry two copies of each gene – one each from our Mother and Father. If each one of them are carriers of CF – that is, they each carry ONE defective gene and one “regular” gene, each child they have has a 50% chance of being a Carrier, 25% chance of having a child with no defective genes (non-carrier) and 25% of having a child who has two copies of the mutated gene (and thus has CF).

Carriers often don’t know their carrier status until they end up with a child with CF, or they have genetic testing to determine if they carry a mutated gene.

How are you diagnosed with CF?

Up until recently, people (usually children) would show specific signs that collectively sparked doctor’s minds to test for CF. For me, it was a bout of Pneumonia after being sick with the flu along with my two sisters that led my pediatrician to consider the possibility. They got better from the flu virus; I did not. I continued to be sick, had problems keeping on weight, had greasy stools and gas, and at a year old, I was just not thriving like healthy children did.

Most CF patients are diagnosed earlier in life, but there are many stories of people with CF finding out later – at 10 years old, 16, 25, even at 50 years old!

Reaching a diagnosis depends on so many different variables –  when you were born (when CF wasn’t well known at all), where you lived (perhaps your local doctors didn’t have a lot of experience with CF), your ethnic ancestry (CF tends to occur more often in Caucasians with Northern European roots), family history (many families have multiple members with CF), your particular medical system, and even your personal insurance situation – so it’s easier than you think that someone can slip through the cracks and not discover their diagnosis until later in childhood or adulthood.

Diagnosing CF and Carrier Status

1. Sweat Test – my pediatrition suspected CF and ordered a sweat test to be done, and as they say, the rest is history. The Sweat Test determines the level of chloride in sweat, and the patient “score” determines if a person has CF, is borderline (and requires additional testing) or if a person does not have CF. (Sweat tests do not determine carrier status).

2. Genetic Testing. Later in life, I participated in a Gene Study to determine which mutation(s) of the CF gene I carried; a Genetic test is another way to determine CF status, although it is still secondary to a Sweat Test in determining the level of chloride in sweat.

Of course, as the world becomes smaller and people from different cultures come together, the gene pool spreads out more, and people from two-culture lineage can carry the gene (silently) until one day they have a child with someone else who carries a defective gene. Of course, as mentioned above, with each birth, a child with parents each carrying one defective gene will have a 25% chance of developing CF, a 50% chance of carrying one copy of the mutated CF gene, and 25% of carrying two healthy copies of the gene.

Thankfully, many hospitals and states now perform mandatory CF testing as soon as a child is born. This is because early intervention can only benefit patients – getting treatment for lung infections and digestive problems early on may slow down the damage to organs that ultimately results in death, providing not just quantity, but quality of life.

Next in series:

What is it like to have CF?


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