Cystic Fibrosis

Exam Cram

• Cystic Fibrosis is caused by a delta F508 mutation in the ion channel CFTR gene, causing thick mucuous; inherited in an autosomal recessive inheritance pattern

• Presentation: poor growth, recurrent respiratory infections, finger clubbing

• Diagnosis: sweat test- raised Na+ levels

• Complications: diabetes, pseudomonas colonisation

Outline

Background

• Autosomal recessive inheritance; CFTR gene, delta F508 mutation

• Baseline rate of carrier is 1/25, 4%. 

• Ultimately fatal disease, life expectancy currently 30-40yrs

Assessment

History

• Poor growth, 

• Recurrent respiratory infections,

Examination

• Finger clubbing

• Nasal polyps

Investigations

• Screened as part of the Newborn Screening

• Sweat test: high Na+ diagnostic

• Pulmonary function tests

• Deranged LFTs

Diagnosis

Diagnosis: raised Chloride in sweat or genetic testing

Management

• No disease modifying therapies in the UK

• Antibiotic nebulisers

• Pancreatic supplements

• Mucolytics and chest physio

• NIV, lung transplants

Med Reg Notes

Curing Cystic Fibrosis

Currently gene therapy is being developed in the USA: a once off injection, that is very expensive. 

Preventing Cystic Fibrosis

Due to it being an autosomal recessive condition, prenatal screening to chose embryos with only heterozygous traits in those with the disease has the ability to greatly reduce the incidence of the cystic fibrosis trait and disease. 

Complications

• Bronchiectasis

• Pseudomonas lung colonisation

• Staph aureus lung colonisation

• Diabetes mellitus (type 3), from

• Pancreatitis

• Liver cirrhosis

• Infertility (in males, failure of vas deferens)

• Bronchial artery aneurysm: PC haemoptysis, Investigation: CTPA, Mx tranexamic acid

Lung transplant

Indications: home oxygen

Contraindications

• BMI < 15

• Active mycobaceterial infection (not pseudomonas colonisation)

• Persistent non compliance- 5+

Infertility

• 98% CF Men are infertile

• 25% CF Females are infertile

• 15% population baseline infertility rate

Resources and References

1. https://www.nhlbi.nih.gov/health/cystic-fibrosis/diagnosis#:~:text=Newborn%20screening%20for%20cystic%20fibrosis,cause%20your%20baby%20brief%20discomfort.

Produced 2024