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Cystic Fibrosis

Written by Xixi Richards, Edited by Christopher LeBoa, Edited by Courtney Coleman

 

Overview 

Cystic fibrosis is a hereditary genetic disease that affects an estimated 40,000 people in the United States (1). In addition, approximately 1 in 30 people are carriers of the CF gene (1). People living with cystic fibrosis are immunocompromised as thick mucus traps harmful pathogens in their bodies (1). This disorder mainly affects the respiratory, digestive, and reproductive systems (2). 


Symptoms

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that incorrectly encodes the CFTR protein. The mutated protein is unable to move chloride to the cell's surface, causing the mucus of many organs, such as the lungs and pancreas, to become thick and sticky. The disorder presents with a multitude of symptoms, including respiratory symptoms such as “a persistent cough that produces sputum, wheezing, exercise intolerance, repeated lung infections, inflamed nasal passages or a stuffy nose, [and] recurrent sinusitis” (3). Some digestive symptoms include

foul-smelling, greasy stools, poor weight gain and growth, intestinal blockage, particularly in newborns (meconium ileus), chronic or severe constipation, which may include frequent straining while trying to pass stool, eventually causing part of the rectum to protrude outside the anus (rectal prolapse) (3).

Other symptoms include salty-tasting skin, nasal polyps, poor growth or weight gain in childhood, and male infertility (4).


Inheritance and Diagnosis

Cystic fibrosis is a result of both parents passing on one altered gene to their children, who will end up with two altered CFTR genes (2). If both parents are heterozygous, their children will have a 25% chance of having cystic fibrosis, a 50% chance of being carriers of the cystic fibrosis gene, and a 25% chance of them not being carriers at all (1).


Newborns are all required to be screened for cystic fibrosis within the first 2-3 days of life, and most cases of cystic fibrosis are diagnosed by the age of 2. Most states will do a screening for immunoreactive trypsinogen (IRT), a chemical produced by the pancreas that is normally high in people with cystic fibrosis. Some states will also require a DNA test in the newborn to look for some of the gene mutations that are associated with cystic fibrosis. Another test includes the sweat test, which checks for chloride levels, and it is the standard test to evaluate the possibility of someone having cystic fibrosis (5).


Treatment and Prevention

The best method of preventing a child from inheriting this disease is to run genetic testing on the parents. If both parents have this gene, then their best option would be to get a prenatal diagnosis, since cystic fibrosis can be diagnosed at 10-12 and 15-20 weeks of gestation (2). Once diagnosed, there are many different treatments that are often personalized, since cystic fibrosis symptoms and severity can differ drastically between people. These treatments can range from, or be a combination of, simple outpatient therapies and pulmonary rehabilitation to surgical procedures like a lung transplant to help with breathing (3). One step all people with cystic fibrosis must do is partake in routine healthcare and vaccinations, as those with cystic fibrosis are immunosuppressed due to the thick mucus trapping pathogens in the body, making them more susceptible to infection. Other treatments to directly combat the effects of cystic fibrosis are airway clearance therapies, inhaled medicine to thin mucus, a pancreatic enzyme supplement, a specialized fitness plan to improve lung function, and CFTR modulators, which are only effective in those with specific mutations in the CFTR gene. While people with cystic fibrosis rarely used to live past elementary school, advances in medicine and care now allow many with cystic fibrosis to live long lives.

 

References

  1. Cystic Fibrosis Foundation. About Cystic Fibrosis. Cystic Fibrosis Foundation. Published 2022. https://www.cff.org/intro-cf/about-cystic-fibrosis

  2. John Hopkins Medicine. Cystic Fibrosis. www.hopkinsmedicine.org. Published 2022. https://www.hopkinsmedicine.org/health/conditions-and-diseases/cystic-fibrosis#:~:text=CF%20causes%20thick%20mucus%20that

  3. Mayo Clinic. Cystic fibrosis - Symptoms and causes. Mayo Clinic. Published November 23, 2021. https://www.mayoclinic.org/diseases-conditions/cystic-fibrosis/symptoms-causes/syc-20353700#:~:text=Cystic%20fibrosis%20is%20a%20disorder

  4. Centers for Disease Control. Cystic Fibrosis. Centers for Disease Control. Published May 9, 2022. ‌https://www.cdc.gov/genomics/disease/cystic_fibrosis.htm

  5. National Heart, Lung and Blood Institute. Cystic Fibrosis - Diagnosis | NHLBI, NIH. www.nhlbi.nih.gov. Published March 24, 2022. https://www.nhlbi.nih.gov/health/cystic-fibrosis/diagnosis 

  6. John Hopkins Medicine. Cystic Fibrosis. www.hopkinsmedicine.org. Published 2022. https://www.hopkinsmedicine.org/health/conditions-and-diseases/cystic-fibrosis#:~:text=CF%20causes%20thick%20mucus%20that

  7. Mayo Clinic. Cystic fibrosis - Symptoms and causes. Mayo Clinic. Published November 23, 2021. https://www.mayoclinic.org/diseases-conditions/cystic-fibrosis/symptoms-causes/syc-20353700#:~:text=Cystic%20fibrosis%20is%20a%20disorder

  8. Centers for Disease Control. Cystic Fibrosis. Centers for Disease Control. Published May 9, 2022. ‌https://www.cdc.gov/genomics/disease/cystic_fibrosis.htm

  9. Cystic Fibrosis Foundation. About Cystic Fibrosis. Cystic Fibrosis Foundation. Published 2022. https://www.cff.org/intro-cf/about-cystic-fibrosis

  10. National Heart, Lung and Blood Institute. Cystic Fibrosis - Diagnosis | NHLBI, NIH. www.nhlbi.nih.gov. Published March 24, 2022. https://www.nhlbi.nih.gov/health/cystic-fibrosis/diagnosis

 

This post is not a substitute for professional advice. If you believe that you may be experiencing a medical emergency, please contact your primary care physician, or go to the nearest Emergency Room. Results from ongoing research is constantly evolving. This post contains information that was last updated on March 14, 2024.

 

Xixi Richards is a second year majoring in microbial biology and music at UC Berkeley.


Christopher LeBoa is PhD student in the School of Public Health at UC Berkeley studying typhoid and avian influenza.


Courtney Coleman is a master's degree candidate in biology at Harvard and Co-President of Students vs Pandemics.

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