Danger level: High

What is it?

Cystic fibrosis (CF) is an inherited, life threatening, disease affecting many organs in the body.

Who gets it?

CF is a genetic disease, meaning that it’s inherited. It is the most common lethal disease inherited in the white population.

Our DNA is contained in genes. They are arranged in structures called chromosomes. We all have 23 pairs of chromosomes, or a total of 46 single chromosomes. The fact that there are pairs of chromosomes means that we have two copies of each gene – one on each one of the chromosome pairs.

Cystic fibrosis is caused by a defect in a gene. That gene is located on one of our chromosomes. If someone has the defective gene in both copies of the chromosome pairs they are sick with CF. If they have the defective gene on one of the chromosome pairs, they are called carriers.

If two parents are carriers for the CF defective gene, their children have a 25% chance of inheriting that gene from them, as can be seen in this diagram (which you may know from another article we did here, about tay sachs disease):

Photo by Cburnett.

Who tends to have the defective gene?

Mostly white people from northern Europe, North America, and Australia/New Zealand. In these people it can happen in 1 out of 3,500 births.

What causes it?

As mentioned above, CF is caused by a defective gene. Each gene in our body is responsible for something: a molecule we produce, a trait we have. The CF gene is responsible for a molecule in our body called CFTR, which is a sort of channel in the cells of our airways, digestive system, sweat glands and urinary system. The cells in all of these areas can produce mucus, a watery substance.

When someone has the defective gene, the CFTR channel doesn’t work like it should, which causes the mucus to become thick and sticky. This glue-like mucus builds up and causes problems in many of the body’s organs.

How does it feel?

Although there is only a defect in one gene in the body, that defect causes many problems, in many parts of the body (not everyone with the disease has all of these. It varies with the severity of the disease):

1. Intestines:
   After a baby is born, they pass their first stool. Babies with CF have such a thick stool that it doesn’t pass and causes constipation in the baby.
2. Pancreas:
   Our pancreas is responsible for secreting enzymes which help us digest the food we eat. In CF, the pancreas also gets blocked due to the sticky mucus, which causes its enzymes not to reach the intestines to help digest the food. This causes problems with absorbing the food, and children with the disease will have a problem growing or gaining weight; foul-smelling, greasy, diarrhea; vitamin deficiencies, and more.
3. Lungs:
   Since the secretions in our airways are also thick and sticky in CF, these children tend to cough or wheeze. They tend to have frequent infections in their sinuses and in their lungs (pneumonia, bronchitis).
4. Skin:
   The CFTR channel is also present in our skin. This causes problems with the way sweat is produced, which causes the sweat to have higher than normal amounts of salt. Many times parents of children with CF notice there’s a problem for the first time when they kiss their children and taste a very salty sweat.
5. Reproductive organs:
   Males with CF tend to have problems with their semen, while females tend to have decreased fertility and problems with their period.

These are the main problems in children with CF, although there are more.

How is it discovered?

There are a few things that can be done to discover if a child has CF:

1. Sweat test – This test checks the amount of salt in the sweat. If it’s unusually high it hints at CF.
2. Genetic test – In this test, the DNA is checked to see if there’s a mutation in the CFTR gene. It’s done on a blood sample.

There are other tests as well, but these are the main ones.

How is it treated?

There is no cure for CF. The treatment is meant to prevent infections, reduce the amount of thickness of the secretions in the lungs, and maintain adequate nutrition for the child’s growth.

Treatment includes antibiotics, mucus thinning drugs, drugs to help breathing (like in asthma) and other measures. It also includes physical therapy to help clear the secretions, and in severe situations, a lung transplant.

What happens after treatment?

Unfortunately, even though the survival of people with CF has improved over the years, they usually die young (in the past they didn’t survive for many years, but now they can reach their 30s). For unknown reasons, males survive longer than females.

The bottom line – How do I avoid it?

When both parents are carriers of the defective gene, a test can detect that in 60-90% of cases. When it does, the parents can choose to use a procedure called preimplantation genetic diagnosis (PGD) in which a fertilized egg is chosen so that it won’t contain the defective gene, and only than transplanted in the uterus. As mentioned above, the genetic tests can’t detect CF every time, meaning that this isn’t a foolproof way.

Hard as CF is, there’s always hope, as can be learned from this video about Katy, a 23 years old CF patient:

For more personal stories you can visit confessions of a CF husband or Breathing deeply: my life with cystic fibrosis.

What next?

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