Cystic fibrosis Flashcards
What is cystic fibrosis?
An autosomal recessive inherited condition, which predisposes the airways to infection and bronchiectasis
Where does the cystic fibrosis gene lie?
On the long arm of chromosome 7
What does the cystic fibrosis transmembrane conductance regulator (CFTR) do?
Active transport channel for chloride In CF: reduced chloride efflux and increased sodium influx Cilia collapse Excessive inflammation
What are the classes of mutation?
1 - no synthesis 2- no maturation 3- blocked regulation 4- decreased conductance 5- decreased abundance
What neonatal screening is done for cystic fibrosis
Newborn bloodspot day 5 (Guthrie test)
Screen for immuno-reactive trypsinogen
If positive mutation analysis
Sweat test
What are the two cardinal features of cystic fibrosis?
Pancreatic insufficiency
Recurrent bronchopulmonary infection
Treatment for pancreatic insufficiency
Enteric coated enzyme pellets
High energy diet
Fat-soluble vitamin and mineral supplements
Hydrogen antagonist or proton pump inhibitors
Management of recurrent infection
Early years: segregation airway clearance and adjuncts mucolytics prophylactic antibiotics annual influenza vaccination
Common respiratory pathogens in cystic fibrosis
Early years: staphylococcus aureus and haemophilus influenza
Adult - pseudomonas aeruginosa
Other manifestations with CF
dysmotility - meconium ileus, rectal prolapse hepatopathy upper airway polyps and sinusitis diabetes osteopenia, arhtropathy heat exhaustion bilateral abscene of vas deferens vaginal candidiasis, stress incontinence
Estimated survival of CF patient born in 2000s
> 40 years
Describe the vicious cycle due to a CFTR abnormality that comes with persistant respiratory infections
Reduced mucociliary clearance, increased bacterial adherence and reduced endocytosis of bacteria leads to…
bacterial colonisation which leads to…
inflammation, mucus plugging, airway ulceration, airway damage, which leads to…
bronchiectasis
Respiratory complications
Pneumothorax
Haemoptysis - may need embolisation
Why is pseudomonas aeruginosa such a virulent pathogen?
Once colonised, it undergoes a mucoid change, creates a biofilm and microcolonies in an alginate film.
Name the drug of a new class addressing the primary defect in CF
Ivacaftor
