CYSTIC FIBROSIS

___What exactly is it?___________

If you want a one-sentence definition, cystic fibrosis (CF) is a genetic disease that inhibits the functioning of the body's exocrine glands. I can see the blank look on your face. "Um, buddy, hate to admit it, but it's been a LONG time since I took high school biology. What the flark is an exocrine gland?"

Huh. Beats me if I know. Let's look it up.

Webster's 10th Collegiate should do the trick. [Flip-flip-flip] Ah ha! It says that an exocrine gland is "a gland (such as the salivary gland or part of the pancreas) that releases a secretion external to or at the surface of an organ by means of a canal or duct."

So exocrine glands produce secretions via a canal or a duct. Cystic fibrosis causes the body to produce incorrect or inefficient proteins in these glands (compared to those produced in a healthy body). These incorrect or missing proteins result in stickier secretions than normal, which now cannot traverse the narrow ducts they are required to. Instead of providing constant traffic for these secretions, passageways to the lung and digestive system become blocked and ineffectual. As a side effect, sweat glands lose more salt and potassium than normal, which can lead to quicker dehydration.

___So where does it come from?_____________

It's called an "autosomal recessive gene condition." That's a lot less impressive than it sounds, since the process of acquiring blue eyes can be described in pretty much the same way.

Most of us know that each parent provides half of the genes for their kids. The trait of "blue eyes" is considered a recessive gene: Both parents must provide a "blue eye" gene if the kid is to have blue eyes. If one parent provides a "blue eye" gene and the other a "brown eye" gene, then the kid will have brown eyes. (Apparently whatever makes blue eyes brown will work if only one brown gene is present.)

CF works the same way. If only one parent has the CF gene, then there's no possibility that the offspring will actually have CF -- even if the carrier parent passes on his/her CF gene. (You need to acquire a CF gene from both your parents to suffer the effects of CF.) However, if the carrier parent does pass on the CF gene, then the offspring will also be a carrier -- able to pass on their copy of the CF gene to their offspring. Which can be bad, if two carriers produce a child.

About 1 in 20-25 US citizens are carriers, or have a CF gene as part of their makeup. This means that about 1 out of every 400-625 marriages offers the possibility of a child being born with CF. (Hmmm, it's starting to sound like a macabre version of Shirley Jackson's "The Lottery".) The disease is highly focused in the European population; only about 1 in 17,000 Afro-American children have cystic fibrosis, compared to about 1 in 2000-2500 for white folk.

___So what does it do?____________

Almost all CF patients will eventually develop lung disease, which is usually the complication that kills them. Breathing problems occur due to the thicker mucus, which can directly block air passages and also trap harmful bacteria in the lungs so that it cannot be expelled by routine drainage and/or coughing.

This explains why respiratory infections are more dangerous to CF patients. The body's natural instinct when infected is to produce more mucus, yet in a CF person, this mucus only reinforces the containment of the bacteria that needs to be expelled, and the cycle builds off itself. Ways must be found to get rid of this blockage, and allow the bacteria to be destroyed and removed. Physical therapy (pounding the chest and back, creating sound vibrations that move mucus out of the lungs), exercise, aerosols, and antibiotics are four common methods.

The thicker mucus also blocks the tiny passageways used by digestive enzymes to travel from the pancreas to the intestinal tracts, resulting in not enough enzymes to break down the more complex fat and protein molecules. (In addition, the mucus is sometimes thick enough to actually block the intestines themselves.) Because protein and fat are essential to a child's growth and also allow digestion of fat-soluable vitamins, CF children are in danger of stunted growth and not having enough energy to function. Synthetic enzymes are ingested with each meal to ensure that fat and protein are properly absorbed. Even with enzymes, however, CF patients must ingest twice the normal number of fat and protein to make sure they've gotten their daily energy requirements.

The reproductive system is affected by the mucus as well, with detrimental results. As if the emotional burden of wondering whether or not it worth chancing having kids, 98% of boys with CF are sterile from birth due to the blocking of their vas deferens (which are the tiny tubes that carry sperm from the testicles to the urethra). Girls with CF are a bit luckier, since they can still manage to conceive despite the extra secretions.

Finally, the CF body's cooling system (sweat glands) cannot process sodium and potassium effectively, resulting in sweat containing 2-5 times the salt content of normal people. However, this problem is easily remedied by ingestion of salt during heavy physical activity or hot weather.

___So what's the bottom line?______________

To be perfectly frank, no one really knows. Due to ignorance of the disease, and lack of anything to do about it, CF patients born 100 years ago -- perhaps even 30 years ago -- died in infancy or young childhood, due to breathing difficulties or an inability to thrive and grow. It was like the sigil of death emblazoned on your forehead. There really wasn't much hope.

But with the medical progress made in the last 30 years, CF patients have had the world opened up to them. While some still die young, others live into their forties, fifties, perhaps even sixties. Lifespan really depends on which genetic form of the disease people have (there are over 500 registered mutations, plus others that are unregistered), the severity of the problems, and the form and consistency of treatment. The gene for CF was isolated in 1989, and since then genetic therapy (where CF genes in the breathing tract can be replaced by healthy ones) has made some promising breakthroughs -- nothing like an actual cure, but an actual lessening of symptoms for a few months at least. Who knows what possibilities will open up within the next 20 years of research?