Genetic Make-Up of Cystic Fibrosis

So now that we know how a person can get Cystic Fibrosis, we should explore how Cystic Fibrosis is caused on a cellular level.

Cystic Fibrosis is caused by a mutation of the “Cystic Fibrosis Transmembrane  Conductance Regulator (ATP-binding cassette sub-family C, member 7)”  gene. This gene is located on the long arm of chromosome 7 at position 31.2. To be more specific, the CFTR gene can be found on chromosome 7, from base pairs 117,120,016 to 117,308,718.

My brain exploded, too. Don’t worry; there is no test on the location of the mutation that genetically causes Cystic Fibrosis.

CFTR Channels and Chloride Ions

The Cystic Fibrosis Transmembrane Conductance Regulator (ATP-binding cassette sub-family C, member 7), or simply CFTR gene is where the instructions are held for making a protein called the cystic fibrosis transmembrane conductance regulator. Cells that produce mucus, sweat, saliva, tears, and digestive enzymes (most of the liquid produced in the body) need this protein as a channel transporting chloride ions (negatively charged particles) in and out of cells across this membrane. (“Transmembrane” literally means “across the membrane,” hence the name “cystic fibrosis transmembrane conductance regulator”—cool, right?) When these chloride ions are able to be transported across the membranes properly, they help take charge of the water movement in tissues. When the movement of water in cells is regulated (another connection to the name of the protein!) properly, the body is able to produce thin and freely flowing mucus. (Mucus is snot. Well, it’s more than that, too, but that’s probably where you would recognize it best. Mucus also acts as a slippery protection and lubrication on the linings of the respiratory system, digestive system, reproductive system, and other organs.) This protein is also in charge of other channels across cell membranes, including those that transport positively charged sodium ions, which are important in the proper function of organs such as lungs and pancreas.

“In English,” as my mom would say, the CFTR gene creates the protein that regulates the movement of chloride ions across cell membranes. When this protein is working properly, the chloride ions are able to control water movement in tissues that helps produce normal mucus to help protect linings of several different systems and organs in the body. This protein also regulates the movement of sodium ions across cell membranes, which helps the lungs and pancreas work properly.

From the sounds of things, lots of our guts are protected by the proper functioning of the CFTR gene. So, what happens if a person has Cystic Fibrosis? CF is caused by a mutation in the CFTR gene that is passed down as a recessive trait. When the CFTR gene is mutated, the CFTR protein doesn’t fulfill its job properly. This means the chloride ions aren't going to be moving across the cell membranes the way they are supposed to, leading to complications with the water movement in and out of cells. Mucus then becomes sticky and thick; this mucus then can block airways and glands and cause complications within many of the organs of the body.

It is important to know of Cystic Fibrosis in a patient so certain medications or procedures that are needed can be adapted to work properly in the body. (For example, my doctor prefers that I use expectorants when experiencing sinus congestion rather than decongestants; these adjustments can usually be made fairly easily and doctors know what they are doing.) It also is good to know so doctors can keep track of the specific effects Cystic Fibrosis has on that patient’s body. (For example, some mutations have a much smaller effect on the digestive system while others can go as far as to cause diabetes.)

So, that is what happens on the very insides of a person affected by Cystic Fibrosis. These will cause various symptoms and require certain treatments as well, but that can wait until another time.

Keep Hope

-Cystic Sister @---