Sequencing Education Center

Cystic Fibrosis Gene Test

By Dr. Brandon Colby MD, an expert in genetic testing and personalized medicine.

Cystic Fibrosis (CF) is a serious genetic disorder that plagues about 70,000 people worldwide and one in every 3,200 babies are born with it. It is one of the most common genetic disorders among Caucasians. 

The American College of Obstetricians and Gynecologists (ACOG) and the American College of Medical Genetics (ACMG) recommends that all Caucasian couples who are pregnant or considering pregnancy check to see if they are cystic fibrosis carriers. They also encourage those of other ethnicities to have the screening with the knowledge that the detection rate is much lower among non-Caucasian populations.

About Carrier Screening for Cystic Fibrosis

Genetic testing for cystic fibrosis can identify if someone is a CF carrier. Many people decide to have the cystic fibrosis gene test if they have a family history of the disease, but carrier screening is a good idea for everyone. This is especially true for pregnant women, as prenatal screening can help upcoming parents learn about the disease as much as possible and plan for healthcare if needed. 

Carrier testing can identify if you have a faulty cystic fibrosis transmembrane conductance regulator (CFTR) gene. This gene is responsible for causing CF. 

The Cystic Fibrosis Foundation reports that more than 10 million Americans are carriers of one mutation of the CFTR gene.  The delta F508 is the most common mutations and accounts for 70% of all the mutations found. 

Who Should Get Genetic Testing for Cystic Fibrosis

genetic testing for cystic fibrosis

While African Americans, Hispanics, Asian Americans, and other ethnic groups can suffer from this genetic disorder, there are more Caucasians with it. 

Ashkenazi Jewish descendants are at an increased risk for CF mutations. Carrier detection rate is as much as 97% and 1 in 3,000 people of this descent suffer from it. Those who have Ashkenazi Jewish ancestry should seriously consider getting the gene test so they know if they are a carrier.  Again, this is especially encouraged if there is a known family history of CF. 

Prenatal Testing for Cystic Fibrosis

Two cystic fibrosis gene tests during pregnancy women may want to have is amniocentesis or chorionic villus sampling (CVS). 

Amniocentesis tests cells from the amniotic fluid. The test is performed between the 15th and 20th weeks of pregnancy. 

CVS checks cells from the placenta. This test is done during the 10th and 12th weeks of pregnancy. 

Newborn Screening for Cystic Fibrosis

Babies are screened for cystic fibrosis before they leave the hospital during their newborn screen. Every newborn baby has a newborn test to check the levels of a chemical by the pancreas called immunoreactive trypsinogen (IRT). A blood sample is taken from the heel and tested for many different conditions, which includes CF. 

Other Times to Order a Cystic Fibrosis Gene test

Besides having a child, there are other times when someone should consider genetic testing for CF. 

  • Symptoms of CF, such as having frequent respiratory infections and very salty sweat, is a reason to get a genetic test. A sweat test can determine if someone's sweat chloride is too high. 
  • Diagnostic testing is conducted with genetic material, so healthcare providers will order a test if they suspect CF. 
  • When initial diagnostic tests come back positive, a cystic fibrosis gene test can confirm the diagnosis. 
  • When a close relative has been diagnosed with the disorder, family members may want to see if they are carriers with a gene test. 

What to Expect with a Cystic Fibrosis Gene Test

Genetic testing involves taking genetic material from cells. The material can come from:

  • Blood
  • Saliva
  • Tissue

The tissue can come from inside of the cheek using a Q-tip type of apparatus. 

The genetic material goes to the lab for testing. Depending on what was ordered, it can check for CFTR mutations as well as other common mutations to rule out other genetic conditions. The results will indicate any gene mutations found in the sample. 

What the Results Mean

carrier testing

If someone receives their gene test results back showing "carrier status", it doesn't mean that the person's child will suffer from CF or develop the genetic disease. It simply means the person has a CF mutation. The good news is that a child must have two copies of the faulty CF gene, one from each parent. This is why couples should both take a cystic fibrosis gene test, as the results may show a high risk a child will inherit faulty CFTR genes if both have it.

A gene test may show a person has two copies of the specific mutation for CF and that does mean the person either has cystic fibrosis or will develop symptoms. 

How to Find Out if You're a Carrier

Many people believe they have to go through a healthcare provider to receive genetic testing. This is untrue. With the advancements in genomics research, it's now possible to get perform cystic fibrosis gene sequencing in the comfort of your own home. All you need to do is order a test kit and follow the instructions inside of it. The Ultime Genome Sequencing kit from Sequencing.com uses tissue from the inside of the cheek to test for CF gene mutations. It can also test for many different mutations as well. 

Results from in-home genetic testing are accurate, which means those who receive position results should seek genetic counseling from a genetic counselor to understand them fully. 

Are you interested in learning about what diseases can be detected through genetic testing? There are hundreds of genetic disorders that can be identified with a DNA test. 


About The Author

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He's an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of Sequencing.com and the author of Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University's Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (ACMG), an Associate of the American College of Preventive Medicine (ACPM), and a member of the National Society of Genetic Counselors (NSGC).