Cystic Fibrosis

Brian Li

History

• Estimated to have originated in 3000 BC due to migration/mutations
• 1948: First described by pediatric pathologist Dorothy Hansine Andersen in

"Cystic Fibrosis of the Pancreas and Its Relation to Celiac Disease: a Clinical and Pathological Study" (American Journal of Diseases of Children)

• Correlated it w/ lung/intestinal disease
• Hypothesized it was recessive
• 1952: Paul di Sant'Agnese discover abnormality in sweat electrolytes used to develop test for CF
• 1989: Lap-Chee Tsui led a team that discovered the gene responsible for CF

Symptoms

• Respiratory Related: Mucus assoc. w/ CF clogs air tubes:
• Persistent cough that produces thick mucus
• Wheezing
• Breathlessness
• Exercise intolerance
• Repeated lung infections
• Inflamed nasal passages or a stuffy nose
• Digestion Related: Mucus block tubes that carry digestive enzymes from pancreas to small intestine
• Foul-smelling, greasy feces
• Poor weight gain and growth
• Intestinal blockage
• Severe constipation
• Requires daily care + frequent medical checkups

Causes

• 1700 known mutations in cystic fibrosis transmembrane conductance regulator (CFTR) gene
• Most common: ΔF508 - deletion (Δ) of 3 nucleotides at 508th position → loss of phenylalanine
• Responsible for making CFTR protein (a chloride ion channel for creating sweat, digestive juices, mucus)
• Autosomal Recessive

​

Mathematical Model

• More common in white population of US
• Whites of northern European origin - 1/3,500
• Hispanics - 1/9,500
• African Americans - 1/17,000
• Asian Americans - 1/31,000
• Average Life Expectancy: 37 Years
• Assume: no mutations, no migrations, all have offspring, randomly select partner

​

Data

Identification

• All states require early infant screening - however, sometimes due to the variety of mutations, CF is not detected
• Immunoreactive trypsinogen (IRT) test: high level of IRT suggests possible CF
• Sweat chloride test: high salt level in the person's sweat is a sign of the disease
• Other tests:
• Chest x-ray or CT scan
• Fecal fat test
• Lung function tests
• Measurement of pancreatic function
• Secretin stimulation test
• Trypsin and chymotrypsin in feces
• Upper GI and small bowel series

Treatment

• Vary case by case, but main goals are:
• Preventing and controlling infections that occur in the lungs
• Removing and loosening mucus from the lungs
• Treating and preventing intestinal blockage
• Providing adequate nutrition
• Medications: Antibiotics, Anti-inflammatory medications, Mucus-thinning drugs, Bronchodilators, Oral pancreatic enzymes
• Chest physical therapy: aided by family or devices
• Pulmonary rehabilitation: Physical exercise, Breathing techniques, Nutritional counseling
• Surgeries: Nasal polyp removal, Oxygen therapy, Endoscopy, Feeding tube, Bowel surgery (Intussusception), Lung transplant

Bioethical Problems

• Genetic Therapy: insertion of a normally functioning gene into deficient host cells using a suitable vector (a vehicle to artificially carry foreign genetic material into another cell) - form of genetic modification
• Transition in Care: Since CF is a lifelong disease, care overtime can be changed as the responsibility for care shifts - some can discontinue treatments
• Reproduction: With a potential to pass down CF or be a carrier for one, there comes the issue of whether to have children or use alternative conception methods
• Lung Transplants: Lungs (unlike hearts/livers) don’t distribute organs (which there aren’t many of) to those statistically more likely to benefit from it.

Thanks for Watching!

Works Cited

Busch, R. “On the History of Cystic Fibrosis.” National Center for Biotechnology Information, U.S. National

Library of Medicine, 1990, www.ncbi.nlm.nih.gov/pubmed/2130674.

“Cystic Fibrosis: Symptoms & Causes.” Mayo Clinic, Mayo Foundation for Medical Education and Research,

13 Oct. 2016, www.mayoclinic.org/diseases-conditions/cystic-fibrosis/symptoms-causes/syc-20353700.

“Cystic Fibrosis: Diagnosis & Treatment.” Mayo Clinic, Mayo Foundation for Medical Education and

Research, 13 Oct. 2016, www.mayoclinic.org/diseases-conditions/cystic-fibrosis/diagnosis-treatment/drc-20353706.

Kaneshiro, Neil K. “Cystic Fibrosis.” MedlinePlus, U.S. National Library of Medicine, 19 Feb. 2018,

https://medlineplus.gov/ency/article/000107.htm.

Sharma, Girish D. “Cystic Fibrosis.” Medscape, WebMD LLC, 13 Dec. 2018,

https://emedicine.medscape.com/article/1001602-overview#a5

Jaffé, A et al. “Gene therapy for children with cystic fibrosis--who has the right to choose?” Journal of

medical ethics vol. 32,6 (2006): 361-4.

Tonelli, Mark R. “Ethical Considerations in the Treatment of Cystic Fibrosis.” Current Opinion in

Pulmonary Medicine, vol. 3, no. 6, 1997, pp. 420–424., doi:10.1097/00063198-199711000-00006.

​

​

​

​