Cystic Fibrosis Flashcards
What is cystic fibrosis?
A genetic disease which leads to abnormally viscous mucus production. This blocks the airways, resulting in repeated chest infections.
What inheritance is responsible for cystic fibrosis?
Autosomal recessive.
Affects CFTR protein production - found on chromosome 7. Mostly due to deletion at c.f508.
It is more common in Caucasians.
What is the pathology behind cystic fibrosis?
In cystic fibrosis, CFTR fails, thus chloride ions do not make it in the airway lumen, meaning fewer sodium ions in lumen (as usually follows chloride ions).
Thus, increased water reabsorption occurs into epithelial cells, with
viscous mucus produced that blocks ducts and impairs the mucosal defence.
What is the normal role of the CFTR protein?
Formation of a channel on mucosal surfaces, allowing chloride ions to move out, and into the airway lumen.
How does cystic fibrosis affect the sweat glands?
Failure of CFTR means there is increased sweat within.
This explains why sweat testing is used in diagnosis.
Which form of infection is associated with a poor prognosis in cystic fibrosis?
Pseudomonas aeruginosa.
How is cystic fibrosis diagnosed?
Sweat testing (will be >60mmol/L of sodium and chloride ions - chloride higher)
Genetic testing (seeks mutation in CFTR gene)
Is cystic fibrosis curable?
No.
How does cystic fibrosis affect fertility?
Sperm production in men is fine, although 95% have absent vas deferens bilaterally.
How does cystic fibrosis typically present?
In a child aged 0-2 years, with recurrent infections, large offensive stools, and a failure to thrive.
What are signs and symptoms of cystic fibrosis?
Salty sweat
Cyanosis
Clubbing
Chest hyperinflation
Bilateral coarse crackles
