Hi, and welcome to another episode of Demystifying Medicine. On today's episode
we will cover cystic fibrosis. We will be discussing the basic biological
principles of cystic fibrosis, the organs affected, and the various treatment
options for this disease. So what do you, a panda, or a neighbour's pet have in
common? You're all made up of cells. The cells can be thought of as a subunit of
life. Inside these cells are a set of instructions called DNA. DNA is made up
of the bases: adenine, guanine, cytosine, and thymine. You can think of these bases
as instructions that code for genes in your body.
For example, the DNA contains instructions for traits such as hair
type, eye colour, and height. When a nucleotide base is added, removed, or
substituted, it is known as mutation. These mutations can change the DNA code,
which may affect the traits that are expressed in your body. Now that we know
the fundamental genetic makeup of our body, let's move to the next big question.
What is cystic fibrosis? Cystic fibrosis is a disorder caused by mutation in the
cystic fibrosis transmembrane conductance regulatory gene, known as
CFTR for short. This mutation occurs on chromosome 7. This disease is an
autosomal recessive disorder which means that the disease is inherited when a
child inherits a defective copy of the gene from both parents who are carriers of
the gene. A carrier is an individual has a defective copy and a normal copy of a
gene and is unaffected themselves. The CFTR gene codes for the CFTR
protein, which is an important chloride channel. The purpose of the channel is to
pump ions in and out of the cell. The symptoms and associated complications of
cystic fibrosis are caused by the dysfunctional CFTR protein channel which
is found throughout the gastrointestinal tract. Affected individuals have elevated
sweat electrolyte levels, pancreatic insufficiencies and lung infections.
These signs are observed in most patients but not all since severity of
the disease can range widely amongst individuals. In Canada, 1 in 3,600 are
born with this disease. Studies have shown that cystic fibrosis is
more frequent in European Caucasian populations than in any other population
around the world. In addition, in the mid 1900s, the median survival age of
individuals with this disease was eight years, but today the median survival age
has drastically improved to thirty years, mainly due to better understanding of
the disease and improved clinical approaches. Now that we know more about
the disease itself let's talk about what organs are affected and the various
treatment options available. Recent studies have shown a higher
understanding of the underlying causes of cystic fibrosis at a genetic level.
More than 1,500 genetic mutations have been linked to the onset of this disease.
However, the most relevant mutation found in 66% of affected
patients is the deletion of the phenylalanine in position 508
on the CFTR gene. This inherited disease mainly infects the lungs, pancreas, liver,
intestine, and sinuses. The most prominent organ affected are the lungs. Excess
mucus caused infections and eventual permanent lung damage due to trapped bacteria.
Normal digestive functions are also altered by this disease, as a mucous
blocks digestive enzymes from reaching the intestines.
Therefore food, specifically fats and proteins, are not digested properly in
patients. Finally, inflammation and infection of the sinuses is a common
effect of this disease, as this disease affects the epithelium found in the
upper respiratory tract. With this advanced knowledge of the causes of cystic
fibrosis, a number of treatments have been proposed with intent of these
treatments being to prevent and control infections in lungs by removing mucus
and to prevent blockages in the intestines. A number of treatments for
this disease are available including antibiotics for infections of the
airways, chest physical therapy, and other specific medications.
Antibiotics are generally the primary treatment for people with cystic
fibrosis as they most likely will have a lung infection. Based on the type of
bacteria and the severity of the patient's condition, there are different
types of antibiotics that are available. Some of which include oral, inhaled, or
intravenous antibiotics. A second type of treatment is chest physical therapy
which serves us a way to loosen and remove mucus from the lungs. This should
be done 3 to 4 times a day and it involves repeatedly pounding one's chest
and back in order to dislodge the mucus. As it might be physically demanding for
some people there are devices such as mechanical precursors or a positive
expiratory pump mask which both serve the purpose of clearing mucus from the
airways. Cystic fibrosis can also be treated by
medications most notably a group called bronchodilators which help to open the
airways by relaxing the surrounding muscles. Finally, as mentioned before, the
pancreas and intestines are unable to function officially because of this
disease. Digestion of food becomes difficult and eventually malnutrition
becomes a cause of the disease. Prevention of malnutrition has become a
greater focal point in recent years as it could help the patient fight a
persisting lung infection. Oral pancreatic enzymes are provided to help
digest fats and proteins and supplements of vitamin A, D, E, and K are provided to
replenish the fat soluble vitamins that the intestine can no longer absorb. By
implementing these techniques we can hope to continue lessening the incidence of this disease.
That's all for today! Thanks for joining us on this episode of Demystifying Medicine!