cystic fibrosis Flashcards
what type of dusease is CF
Autosomal recessive
what is the main cause of mot ifity and morgaligu
pulmonary dusease and resp failure causes death un 90%
what haopens if both parents are carriers
1/4 chnace a chikd will be affected
2/4 chance carrier
1/4 chance unaffected
what does CF occur due to
a mutation in the transmembrane conductance regulator protein (CFTR) which is coded on chromosome 7
what does abnormal transport of cl- and na due to mutation on CFTR lead to
reduced airway surface liquid (dehydrates mucous layer)
thicky sticky mucous
shesring
impaired bacterual killing via neutrophils
how many mutation classes is there
6, based in synthesis, processing/trafficking and fucntion of CFTR. class 1-3 cause severe disease and 4-6 cause milder disease the most common id F508 which is class 2
what is some antenatal testing for CF
done follwing identifucation of CF parent or sibling
pre implantatkon genetic diagnosus
chorionic villous sampling
amniocentesis
what is neonatal screening for CF
newborn bloodspot day 5
(guthrie test)
screen positive - regerred for clinical assessment and sweat test
proportion of disgnoses missed
when is sweat testing done
any time postnatally
measures concentration of cl- excreted in the sweat which would be elevated in CF
> 60 mm per litrr is abnormal
what are the three diagnostic outcomes of testing
CF
NOT CF
CF - screen positive inconclusive diagnosis (SPID)
where does CF effect
it is a multisystem disease and can affect any part od the body eg pancreatuc insifficiency diabetes infection and bronchiectasis
how does CF cause pancreatic insufficiency
CFTR mutation also affects the pancreas
the oactess produces enzymes that digest food. lack of rnzymes causes:
1. malabsorption
2. abnormal stools- pale, offensive, float
3. failure to thrive
impirtance of record, groth charts
what are the levels of pancreatic fucntion
class 1-3 are pancreatic insuffucient and 4-6 have some pancreatic function
we only need about 5% of CFTR fucntion to have sufficient oancreatic function and be asymptomatic
what can recurrent bronchipulmonary infection cause
pneumonia
bronchiectasis
scarring
abscesses
why does pulmonary infection occur
CFTR causes
- abnormal electrolyte transport across cell membrane
- degydratkon of airway surface layer (water later which allows mucoys to slide easiky uo airways to be coughed up)
- decreases mucociliary clearance
- mucous sticks to mucosal surface and causes shearing damage
- increased bacterial adherence
- decreased bacterial killing
so u are more prone to chest infectjons
