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Steps for a Cystic Fibrosis Carrier

Thu, 12/24/2015 - 09:36 -- IV Solutions

Cystic fibrosis is an autosomal recessive trait. This means that a child must inherit the CF gene from BOTH parents. Otherwise, the child does not have the symptoms of cystic fibrosis. The parents of a child with cystic fibrosis are known as carriers. This means that, although they do not have the symptoms of cystic fibrosis, they have 1 gene with the cystic fibrosis trait.

Cystic fibrosis is much more prevalent in european populations (including US citizens with roots in Europe). 1 in 25 caucasians in America are carriers of this recessive gene. A carrier is someone who has only 1 gene and expresses no symptoms of cystic fibrosis. Carriers have a 50% chance of passing on this gene to their children.

Cystic fibrosis is less prevalent in other populations, but it still occurs.

  • Ashkenazi Jewish, 1/24
  • Caucasian, 1/25
  • Hispanic, 1/58
  • African American, 1/61
  • Asian American, 1/94

*American College of Medical Genetics. Technical Standards and Guidelines for CFTR Mutation Testing, 2006 Edition. Retrieved Sept 11, 2015

Cystic Fibrosis Inheritance

A change in a gene that is located on chromosome 7 is responsible for making a protein called CFTR (cystic fibrosis transmembrane regulator). This is what causes the mucus in people with cystic fibrosis to become thick and results in the other symptoms of CF.

The following charts are called punnett squares. They show what conditions are necessary for a child to be born with cystic fibrosis. The small “n” represents the recessive, cystic fibrosis, gene. The capital “N” represents the dominant gene that is absent of the cystic fibrosis gene.

  • NN (no cystic fibrosis genes and no expressions of cystic fibrosis).
  • Nn (carrier of cystic fibrosis genes but no expressions of cystic fibrosis).
  • nn (both genes are cystic fibrosis genes and symptoms of cystic fibrosis are expressed).

When both parents are carriers, the child has a ¼ chance of inheriting cystic fibrosis.

  • Nn (carrier of cystic fibrosis genes but no expressions of cystic fibrosis).
  • nn (both genes are cystic fibrosis genes and symptoms of cystic fibrosis are expressed).

When one parent has cystic fibrosis and one parent is a carrier, the child has ½ chance of inheriting cystic fibrosis.

Cystic Fibrosis Carrier Screening

Testing if you are a carrier is performed through a simple blood test. Since there are over a thousand mutations of the gene associated with cystic fibrosis, the carrier screening can only identify the most common variations. This screening still identifies 85 to 90 percent of carriers in caucasian populations. Other races/ethnicities have a lower percentage of carriers so testing is often unnecessary. However, tests are available if the need arises.

If both parents are carriers, it is common to have a prenatal test administered to determine if the baby has cystic fibrosis.

If both parents are carriers and considering having a child, there are many options available to you. Meeting with a genetic counselor and consulting them about your situation could be very beneficial.

Learn more about Cystic Fibrosis with us

Cystic Fibrosis Symptoms

The first step towards managing cystic fibrosis is understanding the symptoms. Read more about what the symptoms are, how to manage them, and how to prevent further complications.

Cystic Fibrosis Diet

Cystic fibrosis has many detrimental effects on the digestive system. Aside from the daily treatments, people with cystic fibrosis also must pay close attention to their diet. Learn more about the foods and eating habits that help people with cystic fibrosis lead healthier lives.

Cystic Fibrosis Treatments:

Cystic fibrosis needs to be treated daily. Learn more about the best treatment methods and what you can do to manage your symptoms. Here are a few tips to improve your health.

Common Complications

Cystic fibrosis is associated with a few common complications and chronic ailments. These can affect the digestive system, the sinuses, or even blood sugar. Learn more about common complications and what can be done to alleviate the struggles associated with them.


FAQ: Carrier Testing for Cystic Fibrosis. UCSF Medical Center. Nov 2, 2010. Accessed Sept 11, 2015

Carrier Testing in CF. Cystic Fibrosis Foundation. July 21, 2015. Accessed Sept 11, 2015

Cystic Fibrosis Everything you need to know about being a carrier. My Doctor Online The Permanente Medical Group. 2008. Accessed Sept 11, 2015

What does it mean to be a cystic fibrosis carrier? about health. Dec 10, 2014. Accessed Sept 11, 2015

Cystic Fibrosis Carrier Screening-What If I Am a Carrier? WebMD. Sept 9, 201. Accessed Sept 11, 2015

Update on Carrier Screening for Cystic Fibrosis. ACOG(American Congress of Obstetricians and Gynecologists). April 2011. Accessed Sept 11, 2015