Cystic Fibrosis

What is it?

Cystic Fibrosis is a medical disorder that causes thick mucus build up in the lungs.  Normally, this mucus is brought up to the pharynx of the throat and either spat out or swallowed.  Build up of mucus can block airways and result in lung infections.  It also can cause mucus build up in the pancreas and block the secretion of digestive enzymes, leading to digestive problems.

How is it inherited?

Cystic Fibrosis is an autosomal recessive gene carried in 1 out of 39 Caucasians.  It takes two defective genes for cystic fibrosis to occur.  Most of the time cystic fibrosis is detected early in life, around the age of 2.  In milder cases, people may not be diagnosed until ages as late as 18.

How does it work?

People with cystic fibrosis have a mutated gene that codes for a protein that transports Cl­^- ions in various parts of the body.  Cl^- is very important in many body systems.  The protein is called the cystic fibrosis transmembrane conductance regulator (CFTR).  CFTR channels help to create a watery layer that lines the outer walls of the trachea and bronchi.  It does this by transporting directly transporting Cl^- and indirectly transporting Na⁺ into the lumen (the inside) of the trachea and bronchi.  Because water often follows ions into and out of cells in order to maintain ion concentrations, a process called osmosis, water is brought into the lumen.  This watery mixture of Cl^- and Na⁺ is called saline.  It provides a surface for mucus (which acts to collect dust and other foreign particles) to “float” over as it is transported in an escalator-like fashion out of the lungs.  Without this layer of saline for the mucus to float on, mucus can build up in the lungs, block airways, and provide a breeding ground for infections.

CFTR channels are also important in the pancreas and have similar functions.  Without them, mucus build up in the ducts of the pancreas can prevent digestive enzymes made in the pancreas, from reaching the intestines.

Prognosis?

Without treatment, cystic fibrosis is lethal.  Mucus build up can prevent proper ventilation and not allow the digestive system to function properly.  So far, there is no “cure all” for cystic fibrosis.  The average lifespan of someone with cystic fibrosis is about 38 years old.  A patient may be in and out of the hospital throughout their life and may have many different routines they have to go through and pills they have to take to be able to live.

Treatment?

 Kalydeco

o   Pill for people 6 and older which helps the CFTR protein to function.  This drug was approved in January by the FDA.

o   It is the first to address the underlying cause of the disease and not just the symptoms.

o   The drug only works with people with the G551D mutation of the gene.

·         Postural drainage and percussion

o   Helps to free up mucus in the lungs by pounding on the chest or back and then coughing up the freed mucus

o   This is also done with special vests that fill with air and vibrate the chest cavity and special hand held hammers that can be used to free mucus in a specific spot in the lungs.

·         Inhaled medications that act as mucus thinners

·         Antibiotics to treat infections often caused by mucus build up

·         Hypertonic saline mists that help to free up mucus in the lungs

·         PICC lines which allow a direct line into the bloodstream to allow intravenous medication.

·         Proper nutrition

o   People with cystic fibrosis have a difficult time gaining weight due to the inability of the digestive system to metabolize food properly

o   Often people with cystic fibrosis have to eat several thousand calories a day to try and maintain proper metabolism.

o   Supplements of different vitamins are often taking

o   To allow proper digestion, people with cystic fibrosis take synthetic enzymes to help break down the food they eat

·         Lung transplantation is possible if lung function is greatly reduced

Research is being done in gene therapies to replace the missing or dysfunctional CFTR gene.

Sources:
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001167/
http://www.cff.org/treatments/Therapies/

Silverthorn, D. Human physiology an integrated approach. 6th. Pearson, 2012. Print.