Cystic Fibrosis

Question 1

why does cystic fibrosis happen? what is there a defect in?

Answer 1

Cystic fibrosis (CF) is an autosomal recessive disorder causing increased viscosity of secretions (e.g. lungs and pancreas).

defect in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which codes a cAMP-regulated chloride channel

Question 2

which chromosome ad gene is affected?

Answer 2

delta F508 on the long arm of chromosome 7

Question 3

how many people does it affect?

Answer 3

1 in 2500

Question 4

which organisms colonise CF patients?

Answer 4

Staphylococcus aureus
Pseudomonas aeruginosa
Burkholderia cepacia*
Aspergillus

*previously known as Pseudomonas cepacia

Question 5

presenting features

Answer 5

neonatal period (around 20%): meconium ileus, less commonly prolonged jaundice
recurrent chest infections (40%)
malabsorption (30%): steatorrhoea, failure to thrive
other features (10%): liver disease

Question 6

other features

Answer 6

short stature
diabetes mellitus
delayed puberty
rectal prolapse (due to bulky stools)
nasal polyps
male infertility, female subfertility