Cystic Fibrosis (CF)

Cystic Fibrosis (CF)

If you have just found out through carrier testing that you and/or your partner are carriers of cystic fibrosis or through prenatal testing that your baby has cystic fibrosis or may have cystic fibrosis and are looking for more information, Genetic Support Foundation is a good starting point.

There are other important resources out there, including your doctor and genetic counselor. We have also compiled a list of resources that can provide you with additional information and support.

After reviewing the information below, if you have a question that you are having difficulty finding an answer for, please feel free to contact us.

Overview of Important Information about Cystic Fibrosis (CF)

Cystic fibrosis (CF) is a genetic disease that primarily affects the lungs and digestive system. CF is seen in all ethnic groups, however it is most common in individuals of Northern European Caucasian ancestry with ~1 out of 2,500 babies born with CF. CF is an autosomal recessive condition, which means that both mom and dad have to be “carriers” in order to have a child with CF.

Individuals with CF produce unusually thick, sticky mucus (our mucus is usually thin). The change in the consistency of their mucus can cause problems. The main problems involve:

  • Issues with the lungs leading to lung infections and subsequent lung damage
  • Obstruction of the pancreas which can prevent important enzymes from helping the body break down food and absorb vital nutrients

The outlook for individuals with CF has changed dramatically and many people with CF can now expect to live into their 30s, 40s and beyond.

Although life expectancy has improved dramatically for individuals with CF, the medical care needed for someone with CF can be intense.



How does someone get CF?

CF is what we call an autosomal recessive condition. Autosomal means that the gene or instruction involved in CF is found on one of the first 22 chromosomes (called the autosomes, hence autosomal), not the X or Y (sex chromosomes). The gene for CF is called CFTR and is found on chromosome 7.

A gene is basically an instruction to build a protein. The  CFTR gene codes for a protein that controls the movement of salt and water in and out of the cells in our body. When this protein is made correctly, it helps keep mucus in the body thin. A person who has CF has CFTR genes that do not work correctly and this can result in thick and sticky mucus in the body which can cause problems with breathing, digestion and fertility.

Autosomal chromosomes come in pairs, we inherit one from our mom and one from our dad. Along the chromosomes are the individual instructions or genes. So, we get one chromosome 7 from our mom and one chromosome 7 from our dad, therefore, we get one CFTR gene from each parent(since it is found on chromosome 7).

Recessive means that in order to have CF, neither of the CFTR genes are working as usual, the one that we inherit from our mom and the one that we inherit from our dad. If only one CFTR genes is not working as usual, the individual is considered a “carrier” of CF and is not expected to have symptoms of the disease.

There is nothing mom and dad can do to cause or prevent CF. If both mom and dad are carriers of CF, there is a 25% chance with each pregnancy to inherit the condition (therefore, a 75% chance they will not get the condition). To read more about autosomal recessive inheritance, click here.



What are the symptoms of CF?

In people with CF, because both copies of their CFTR genes are not working, their body produces unusually thick, sticky mucus (our mucus is usually thin). The change in the consistency of their mucus can cause problems including:

  • Lung infections and subsequent lung damage
  • Obstruction of the pancreas which can prevent important enzymes from helping the body break down food and absorb vital nutrients

Other symptoms of CF include:

  • Persistent coughing
  • Wheezing or shortness of breath
  • Poor growth and slow weight gain, in spite of a good appetite
  • Frequent greasy, bulky stools or difficulty in bowel movements
  • Very salty-tasting skin
  • Infertility (may affect men and women, but men are more often affected)


What is the long-term outcome for individuals with CF?

We now know that there are different levels of severity in CF. Some individuals have very mild CF with symptoms that may not appear until later in life, others are diagnosed shortly after birth based on symptoms.

For individuals who have more “typical” CF, the outlook has changed dramatically during the past few decades. In the 1950s, many children passed away during elementary school or before. Since then, tremendous progress has been made in understanding and treatment CF, leading to significant improvement in the length and quality of life for those with CF. Many people with CF can now expect to live into their 30s, 40s and beyond.

According to a recent study published in the Annuls of Medicine in August of 2014, a child born with CF in 2010, on average, has a life expectancy of 37 years for girls and 40 years for boys (1). However, given advances in treatment, a baby born today with CF may live much longer (1).

Individuals with CF get married, some have children, work in jobs they find meaningful and can lead very productive lives.

Although life expectancy has improved dramatically for individuals with CF, the medical care needed for someone with CF can be intense and may include taking many special medications, special diet, exercises, breathing treatments and more. Recently, there are new promising treatments that activate the missing or defective CFTR protein and thereby improve the respiratory health of CF patients.

1. MacKenzie, T, et al. 2014. Longevity of Patients With Cystic Fibrosis in 2000 to 2010 and Beyond: Survival Analysis of the Cystic Fibrosis Foundation Patient Registry. Ann Intern Med;161(4):233-241.

 



Why are couples offered carrier testing for CF during/prior to pregnancy?

People have been offered carrier testing for CF during their pregnancy for over a decade. Depending on your ethnic background, it is actually not uncommon to be a carrier for CF. About 1 in 25, or 4% of Caucasian individuals are carrier for CF. Within the past several years, it has become standard of care to offer CF carrier testing to all pregnant couples, regardless of ethnicity. Part of this is because, although it is relatively rare (affecting only less than 1 in 3,000 births) it is one of the most common recessive genetic conditions AND we can test for it. But why do the testing? Well, the decision to undergo or decline carrier testing should always be a personal one made by the woman/couple.

Some of the reasons couples or individuals choose to have carrier testing for CF include the following:

  • They have a family history of CF and know that their chances of being a carrier are increased. These individuals may want to find out if they are carriers to prepare or consider other options if they are a carrier and their partner is as well.
  • They want to know all they can about their baby before he/she is born. Some couples simply want to do all the testing they can. For some, it is for the purpose of reducing anxiety or to be prepared; other people are uncertain about what they would do if they knew their baby was going to be born with CF and want to be able to consider all of their options.

It is important to know that all babies born in the United States are screened for cystic fibrosis shortly after birth through newborn screening. So, even if you do not have carrier testing, you would find out shortly after your baby is born if he/she has cystic fibrosis.   Some individuals know that even if they were found to be carriers for CF, it wouldn’t change anything about the pregnancy for them, and they decide to wait until after the baby is born to find out for sure.

For more information about carrier testing for CF and other carrier testing options click here.



What is the chance I am a carrier for CF?

It depends on your ethnic background. It is not uncommon to be a carrier for CF, however remember that both members of the couple must be carriers for CF and both members of the couple must pass on the non-working gene in order for the baby to have Cystic Fibrosis. Here is the approximate chance to be a carrier for CF based on ethnic background1:

Race or Ethnic GroupChance to be a Carrier
Caucasian (White)1 in 25 people or 4%
Hispanic1 in 58 people or 2%
African American1 in 61 people or 1.6%
Asian1 in 94 people or 1%



Other Resources

Cystic Fibrosis Foundation

Information about cystic fibrosis from the NIH/NHLBI

Information about cystic fibrosis from KidsHealth  

Information about cystic fibrosis from MedicineNet

 

References

1) American College of Obstetricians and Gynecologists. (2011). Update on carrier screening for cystic fibrosis. Committee Opinion No. 486. Obstetrics and Gynecology, 117(4), 1028–1031.

2) Langfelder-Schwind E, Karczeski B, Strecker M, Redman J, Sugarman J, Zaleski C, Brown T, Keiles S, PowersA, Sumheda G, and Darrah R. Molecular Testing for Cystic Fibrosis Carrier Status Practice Guidelines: Recommendations of the National Society of Genetic Counselors. Journal of Genetic Counseling (2014)


Questions? Get in touch










Genetic Support Foundation
Copyright © 2015 Genetic Support Foundation, Inc