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Cystic Fibrosis Gene Mutation Blood Test

Last updated April 16, 2018

Approved by: Maulik P. Purohit MD MPH

The Cystic Fibrosis Gene Mutation Blood Test is a test to identify genetic mutations in the CTFR gene. It is used to diagnose cystic fibrosis. The test is also used to determine if an individual is a carrier of CF.


What are the other Names for this Test? (Equivalent Terms)

  • CF DNA Analysis Blood Test
  • CF Gene Mutation Blood Test
  • CF Genotyping Blood Test

What is Cystic Fibrosis Gene Mutation Blood Test? (Background Information)

  • Cystic fibrosis (CF) is a genetic disease that affects the mucus linings. The mucus linings cover the airway, lungs, liver, intestines, pancreas, and sweat glands, among other sites in the body
  • Mucus lubricates tissues subject to stress. It also traps particles and microbes before they can breach bodily cells; defensive proteins released with mucus help perform this role
  • Normal mucus is clear and relatively watery. This is because cells release abundant salts, or ions, which in turn causes water to leave the cells and dilute mucus. Cells regulate the release of ions through ion pumps
  • Problems with cells’ ion pumps cause the production of thick mucus that is less able to protect the cells. This is the central defect of cystic fibrosis. In CF, a gene that gives instructions for the creation of the ion pumps is mutated or altered
  • This gene is called the ‘cystic fibrosis transmembrane conductance regulator’ or CFTR gene. Two copies are present in each cell (except sperm and egg cells, which have only 1 copy). It is possible to have one altered copy of the CTFR gene and still make normal mucus. Such individuals are said to be heterozygous carriers of cystic fibrosis
  • Individuals with two altered copies of the CTFR gene will display symptoms of cystic fibrosis. These include breathing trouble, pain, and increased susceptibility to infections
  • It is possible for two seemingly healthy parents to have a child with cystic fibrosis because a child receives genetic material from both parents. This may occur if both parents are carriers – that is, they both have a single altered version of the CTFR gene

The Cystic Fibrosis Gene Mutation Blood Test is a test to identify genetic mutations in the CTFR gene. It is used to diagnose cystic fibrosis. The test is also used to determine if an individual is a carrier of CF.

What are the Clinical Indications for performing the Cystic Fibrosis Gene Mutation Blood Test?

Following are the clinical indications for performing the Cystic Fibrosis (CF) Gene Mutation Blood Test:

  • Following up to an immunoreactive trypsinogen (IRT) or sweat chloride test
  • Family history of CF
  • Testing of expecting parents for carrier status, prior to having (planning for) a child
  • Frequent and persistent respiratory tract infections
  • Trouble breathing
  • Coughing up thick, sticky mucus

How is the Specimen Collected for Cystic Fibrosis Gene Mutation Blood Test?

Following is the specimen collection process for Cystic Fibrosis (CF) Gene Mutation Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected, by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Cystic Fibrosis Gene Mutation Blood Test Result?

The significance of the Cystic Fibrosis Gene Mutation Blood Test result is explained:

  • Possessing one mutated copy of CTFR gene indicates cystic fibrosis carrier status
  • Possessing two mutated copies of the gene indicates cystic fibrosis

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • It is believed that possessing mutated versions of the CTFR gene makes an individual more resistant to the effects of cholera. This is because the toxin produced by the Vibrio cholerae bacterium targets ion pumps, which would be less recognizable if their CTFR gene was mutated

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 15, 2015
Last updated: April 16, 2018