Cystic Fibrosis Case Study

The role genetics plays in the disease.

Cystic Fibrosis (CF) is a disease that is inherited and affects the mucus and sweat production by those glands (McCance & Huether, 2018).  How it is inherited is that parents of children with CF both have to be carriers of the cystic fibrosis transmembrane regulator (CFTR) mutation gene (McCance & Huether, 2018).  Parents do not have to have CF for their children to have CF; they just have to be carriers of the mutation gene (Tabori et al., 2017).  It is very common for people of European descent to inherit CF (McCance & Huether, 2018).



Why the patient is presenting with the specific symptoms described.

The symptoms described in the case study scenario that contributed to the CF diagnosis were thought of possible colic, baby has had many episodes of crying after eating, despite having a good appetite baby is not gaining weight (failure to thrive, FTT), baby’s belly “gets all swollen sometimes,” the baby tastes “salty” when the mother kisses the baby, and sibling has had multiple episodes of “chest congestion” and was hospitalized once for pneumonia (Abid et al., 2017).

The human body is protected against bacteria by first and second lines of defense (McCance & Huether, 2018).  Physical, mechanical, biochemical, and normal flora make up the first lines of defense (McCance & Huether, 2018).  Examples of the physical and mechanical barriers are skin and mucus membranes; antibacterial properties of mucus secretions, tears, saliva, sweat, and other secretions are examples of biochemical barriers; normal flora are good bacteria that protects the human body by preventing bad bacteria from taking over in places like the gut (McCance & Huether, 2018).

CFTR protein pushes chloride ions into secretions to help draw water into these secretions (mucus) to loosen (thin) them (McCance & Huether, 2018).  CFTR protein absence leaves excess chloride ions on the skin.  The thin and slippery mucus protects the sac that lines the lungs, stomach, tissues and organs (McCance & Huether, 2018).  The missing CFTR protein does not leave a way for the body to thin out the mucus (Abid et al., 2017), leaving the body to only make thick and sticky mucus that build up, leading to blockages, frequent infections, and damages in the affected organs (McCance & Huether, 2018).

The pancreas cannot release any digestive enzymes to the small intestine when it is blocked with thick mucus making nutrients and fat not absorbable, leading to FTT (not gaining weight despite good appetite and looking malnourished (McCance & Huether, 2018).  Other gastrointestinal symptoms include fatty stools (McCance & Huether, 2018), abdominal pain after eating due to poor intestinal malabsorption (Tabori et al., 2017), abdominal bloating, constipation, and flatulence (McCance & Huether, 2018).  CFTR also helps the skin regulate sodium ions and fluid absorption; so, in someone with CF, there is less fluid absorption to dilute the sodium ions, leaving the salty taste on the skin (McCance & Huether, 2018).

The second line of defense is the body’s response to damage known as inflammation (McCance & Huether, 2018).  Symptoms are redness, swelling, pain, and heat, collection of fluid at the site, leukocytosis and fever (McCance & Huether, 2018).  In the presence of CF, inflammation causes damage to lungs and pancreas in particular, but other organs as well (McCance & Huether, 2018).  A child or young adult, or their sibling, with a history of severe and recurrent bronchitis, pneumonia, pancreatitis, and hemoptysis is suspect for further CF testing.



The physiologic response to the stimulus presented in the scenario and why you think this response occurred.

In CF, abnormally thick mucus in the airways does not have the same germ-killing properties of normal mucus leading to frequent infections that hampers attempts at treating (clearing) the infections, resulting in a loop of continuous inflammations, scarring, and death (McCance & Huether, 2018).  Viral and bacterial infections, especially culprits like Pseudomonas aeruginosa, Staphylococcus aureus, and Hemophilus influenzae, manifest inflammatory responses that are extreme (McCance & Huether, 2018).  Excessive signals are sent from cells with a defective CFTR protein, resulting in the complement system of antigen-antibody being activated (McCance & Huether, 2018); bacteria, leukocytes (white blood cells) and phagocytes (neutrophils).



The cells that are involved in this process.

The mast cell activates the inflammatory response through the release of mediators such as histamine (McCance & Huether, 2018).  Antigens of the bacteria are presented to helper T cells, who release cytokines, resulting in accumulation of neutrophils (to initiate phagocytosis of the bacteria), signaling or resulting in inflammation (McCance & Huether, 2018).


How another characteristic (e.g., gender, genetics) would change your response.

While some people with CF get severe symptoms or life-threatening complications, others have few signs and symptoms (Tabori et al., 2017), such as with the baby and older sibling in the case study scenario.  Siblings with only one parent in common who is a carrier will not acquire CF.  Abid et al. (2017) reported estrogen hormone elevations disrupt chloride ion and water balance (p. 2). They also measured nasal epithelial Calcium ion-activated Chloride-secretion in women with CF during their menstrual cycle with results that women with CF cannot clear build-up of airway secretions, a hallmark of CF, effectively (Abid et al., 2017).





Abid, S., Xie, S., Bose, M., Shaul, P., Terada, L., Brody, S.,…Jain, R. (2017). 17β-Estradiol Dysregulates Innate Immune Responses to Pseudomonas aeruginosa Respiratory Infection and Is Modulated by Estrogen Receptor Antagonism. Infection and immunity, 85(10), e00422-17. Https://

McCance, K. & Huether, S. (2018). Pathophysiology: The biologic basis for disease in adults and children (8th ed.). St. Louis, MO: Mosby/Elsevier.

Tabori, H., Arnold, C., Jaudszus, A., Mentzel, H., Renz, D., Reinsch, S.,…Mainz, J. (2017). Abdominal symptoms in cystic fibrosis and their relation to genotype, history, clinical and laboratory findings. PloS one, 12(5), e0174463. Https://



   I enjoyed reading your post, it was very detailed and very interesting. I like how you presented the discussion. We all know by now that Cystic fibrosis is an inherited disease and the most common life-shortening autosomal recessive disease among Caucasian populations, with a frequency of 1 in 2000 to 3000 live births. The median predicted survival for CF patients in the United States was 39.3 years (95% CI, 37.3-41.4) according to the Cystic Fibrosis Foundation 2014 Registry Report (Katkin, 2020). As in your discussion, it was common in people of European descent to inherit CF (McCance & Huether, 2018).


Over the years, Cystic Fibrosis (CF) has had significant improvements for early diagnoses and better management for delayed disease progression. The treatments recently are specifically seeking ways to target the genetic mutation causing the disease (Huether & McCance, 2017). Specifically, the correction of the misprocessing of the CFTR protein is helping trial new drugs. Understanding the pathophysiology of the disease can assist in the best treatment plan. For example, Ataluren is now used in research trials, which helps restore the function of mutation in the gene and aids in correcting the chloride channel transport by targeting CFTR protein (Brown, White, & Tobin, 2017).


I wanted also to point out in response to the mother on her 23 mos. We can also educate the mom and the husband of advanced teaching to them, we can give options regarding the CF screening and the disease itself. It will be beneficial for the mother and her husband to contemplate if they choose to have another kid. Newborn screening is universal in the US.  Ideally, when a family member has confirmed CF, other family members should be screened by the same laboratory that tested the affected relative. The screening panel should include familial mutations previously identified as well as the mutations in the standard panel. Genetic counseling should also be available to them and take also into consideration. Researchers have shown that females are more likely to succumb to this disease than men. Although this gender disparity is not researched often, it has been hypothesized that the disease is hormone mediated. This could account for the 23-month-old to not show symptoms as soon as the 6-month-old (Harness-Brumley, Elliot, Rosenbluth, Raghaven, & Jain, 2014). With mother already having two children with CF, it would be beneficial for her and her partner to undergo carrier screening, if not already performed. If considering, genetic counseling would also be of assistance. If both partners are positive for the CF mutation, there are options such as accepting the risk, adoption, and in vitro fertilization, with the use of preimplantation genetic diagnosing (The American College of Obstetricians and Gynecologists, 2017). As providers, it is our responsibility to keep the patient informed upfront regarding any future pregnancies. Again, thank you for your great post.




Brown, S. D., White, R., & Tobin, P. (2017). Keep them breathing: Cystic fibrosis pathophysiology, diagnosis, and treatment. Journal of the American Academy of PAs, 30(5), 23-27. doi: 10.1097/01.JAA.0000515540.36581.92

Harness-Brumley, C.L., Elliot, A.C., Rosenbluth, D.B., & Jain, R., (2014). Gender differences

In outcomes of the patient with cystic fibrosis, Journal of Women’s Health, 23(12). Pp 1012-1020

Huether, S. E., & McCance, K. L. (2019) Pathophysiology: The biologic basis for disease in adults and child ( 8th Ed.) St. Louis, Missouri: Elsevier

Katkin, J. (2019) Cystic Fibrosis: Clinical manifestation and Diagnosis. Up to Date.

Retrieve 10 October 2019 from https//

The American College of Obstetricians and Gynecologists. (2017, June). FAQs171. Retrieved from Women’s Health Care Physicians: