What Is Cystic Fibrosis?
Cystic fibrosis (CF) is an
inherited disease
that causes the body to produce mucus that's extremely thick
and sticky. The mucus in people with CF is thicker than normal
because CF affects cells in the
epithelium
(pronounced: eh-puh-
thee
-lee-um), the layer of cells that lines the passages in the
body's organs. In a person who does not have CF, the epithelial
cells produce a thin, watery mucus that acts like a lubricant and
helps protect the body's tissues. In a person with CF, however,
the thicker mucus doesn't move as easily. This thick, sticky
mucus clogs passages in many of the body's organs and infection
sets in.
The two organs that are most affected are the
lungs
and
pancreas
, where the thick mucus causes breathing and digestive problems.
The thicker mucus has trouble moving out of the lungs, so bacteria
can remain and cause infections. The thick mucus can also be found
in the pancreas
- an organ that produces proteins called
enzymes
that flow into the intestine to support the body's digestion
process. Because the mucus can block the path between the pancreas
and the intestines, people with CF have trouble digesting food and
getting the vitamins and nutrients they need from it.
CF can also affect the liver, the sweat glands, and the
reproductive organs.
What Causes CF?
Approximately 30,000 people in the United States have been
diagnosed with CF, which affects both males and females. It's
not contagious, so you can't catch CF from another person.
Cystic fibrosis is an inherited disease caused by mutations
(changes) in a gene on chromosome 7, one of the 23 pairs of
chromosomes that children inherit from their parents. Cystic
fibrosis occurs because of mutations in the gene that makes a
protein called CFTR (cystic fibrosis transmembrane regulator). A
person with CF produces abnormal CFTR protein - or no CFTR
protein at all, which causes the body to make thick, sticky mucus
instead of the thin, watery kind.
People who are born with CF have two copies of the CF gene. In
almost all people born with CF, one gene is received from each
parent. This means that the parents of kids with CF are usually
both CF carriers - that is, they have one normal and one
defective gene - but the parents may not have CF themselves
because their normal gene is able to "take over" and make
the necessary CFTR protein.
Each child born to parents who are both CF carriers has a 1 in 4
chance of having the disease. Cystic fibrosis occurs most
frequently in Caucasians of northern European descent, in whom the
CF gene is most common - although people of other heritages can get
the disease, too.
People who have a close relative with CF are also more likely to
carry the CF gene - approximately 12 million Americans, or 1
in every 20 people living in this country, is a CF carrier. And
most of them don't know it. Parents can be tested to see if
they carry the CF gene, but because there are hundreds of specific
CF gene mutations (not all of which are known), genetic testing for
CF won't detect everyone who is carrying a CF gene.
Doctors can also perform tests during pregnancy so prospective
parents can find out more about the chances that their child will
have CF. However, these tests also won't always detect a CF
gene.
What Happens When You Have CF?
Doctors diagnose most kids with CF by the time they are 3 years
old, but if someone has a milder form of the disease, it may not be
diagnosed until that person reaches the teen years. Babies are
usually tested if they are born with an intestinal blockage
called
meconium ileus
, which is more common in CF infants.
Other symptoms include:
- frequent lung infections or pneumonia
- persistent wheezing
- persistent cough with thick mucus
- bulky, light-colored, foul-smelling bowel movements or
diarrhea (because food isn't being digested properly)
- failure to gain weight, even though the child eats normal
amounts
- very salty sweat
- poor height growth
- nasal polyps (small growths of tissue inside the nose)
- frequent sinus infections
- fatigue
People with CF get frequent lung infections that can damage
their lungs over time and require strong antibiotics along with
stays in the hospital. They may have trouble growing or gaining
weight because of digestive problems. Adults with CF may also
develop other illnesses, such as
diabetes
(a disease in which a person's blood sugar is too high) or
osteoporosis (a weakening of the bones).
The ends of the toes and fingers may become rounded and
enlarged, a condition that's called
clubbing
.
What Do Doctors Do?
If doctors suspect that a person has CF, they will order a
sweat test
. In this test, the doctor or technician uses a chemical and a very
mild electrical current to cause sweating on an area of skin,
usually on a person's forearm (this test doesn't hurt). The
doctor or technician collects a large amount of sweat in a pad and
then analyzes it. If the test results show a high level of chloride
(a chemical in salt), there's a possibility the person has CF.
In some states in the United States, all newborns are checked for
CF with a blood test, although the blood test isn't as good at
detecting the disease as the sweat test.
Doctors and people with CF can do several things to slow the
progression of the disease and fight its complications. To loosen
mucus, people with CF exercise regularly and may use inhalers (like
kids with asthma use) or
nebulizers
that help deliver medication to the lungs.
Coughing helps people with CF clear the mucus from their lungs.
They may also take antibiotics to prevent or fight lung infections.
Chest physical therapy may also be an important part of a
person's CF treatment routine. After lying down in a position
that helps drain mucus from the lungs, the person has a helper,
such as a parent, gently bang on his or her chest or back to loosen
the mucus. And a newer device called a therapy vest that shakes the
chest allows teens to be more independent by doing their therapy on
their own.
For digestive problems, a person with CF can take enzymes by
mouth in order to help digest food and get
nutrients
from it. A doctor may also prescribe vitamin supplements and a
high-calorie diet.
Living With CF
Right now, there is no cure for CF. Even if symptoms are mild at
first, they get steadily worse over time.
But there is hope. Fifteen years ago, most children with CF
would die before reaching their teens. Now, with new treatments
available, more than half live into their thirties, and new
research is leading to the possibility of a cure. Statistics now
show that nearly 40% of the people living with CF in the United
States are 18 years or older.
Since researchers identified the gene that causes CF in 1989,
they have tried to replace abnormal CF genes with normal ones. Some
are working on finding the right method of delivering that normal
gene into the cells of a person with CF. Other scientists are
trying to find new ways of fighting lung infections and different
ways of moving chloride in and out of cells, bypassing the
defective CFTR protein. In some cases, lung transplants have
extended the lives of people with CF.
If someone you know has CF, you can be a supportive friend by
learning about the disease so you can help other people understand
what your friend is going through. Just hanging out with your
friend and taking part in the activities you enjoy doing together
can be a great help.
If you have CF, focus on staying as healthy as possible by
following your doctor's treatment instructions, taking your
medications, eating right, and exercising. Meeting other teens who
have CF via chat rooms is fine, although personal contact between
two CF patients can present problems since it carries the risk of
passing dangerous bacteria to each other.
Your hospital's child life and CF specialists will have all
kinds of ideas and tips for coping with the disease and keeping
your spirits up. Ask them to recommend groups you might join,
either online or locally. They can provide you with information
about clinical trials, legislative actions, handouts about CF, and
even a college or vocational school scholarship program.
Reviewed by:
Raj Padman, MD
Date reviewed: September 2007
Originally reviewed by:
Mark Weatherly, MD, and Lloyd N. Werk, MD, MPH
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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