cystic fibrosis Flashcards
what type of gene disorder causes CF
autosomal recessive- requires 2 mutated genes (homozygous)
chances of CF if both parents are carriers
1 in 4
how does CF occur
a mutation in the transmembrane conductance regulator protein (CFTR)
where is the CFTR gene coded for
chromosome 7
what does the CFTR mutation cause
chloride gets trapped in the cell
causes water and sodium to enter cell too
excess water, sodium and chloride in cells causes
- Dehydrates airway surface and mucous layer
- Thick mucous sticks to mucosal surface, causing shearing
- Difficult to cough up
- Mucous collects bacteria, reduced ability to fight infection
how many mutation classes are there
and how bad are each
6
1-3 are severe
4-6 are milder
most common mutation
DeltaF508a
class 2 mutation,
antenatal testing happens when
a CF carrying parent or sibling is found
what’s included in antenatal testing
- Pre-implantation genetic diagnosis
- Chorionic villous sampling
- Amniocentesis
neonatal testing includes
Newborn bloodspot day 5 (Guthrie test)
Screen positive -referred for clinical assessment and sweat test
tests for children
sweat test
what does the sweat test look for and numbers
Measures the concentration of chloride excreted in sweat. Elevated in CF.
> 60 millimoles per litre, high chance CF
3 examples of where CF can effect the body
Pancreatic insufficiency
Diabetes
infection and Bronchiectasis
pancreatic insufficiency causes
- Malabsorption
- Abnormal stools -pale, offensive, float
- Failure to thrive
CF classes and effects on pancreas
- Class 1-111 are pancreatic insufficient.
- Class IV-V1 have some pancreatic function
only need 5% CFTR function for adequate pancreatic function
recurrent chest infections causes
–Pneumonia
–Bronchiectasis
–Scarring
–Abscesses
why are infections so frequent?
dry airway surfaces means mucus can’t slide up and down easily
decreased mucociliary clearance
Mucous sticks to mucosal surface and causes shearing and inflammation
increased access to bacteria
decreased bacteria killing
late CF findings on CT
- Tramlines
- Signet rings
- Mucous plugging
- Consolidation (infection)
treatment of pancreatic insufficiency
boosting nutrition:
- REPLACE ENZYMES: (CREON)
- DIET: High energy plus high calorie supplement drinks
- NUTRITIONAL SUPPLEMENTS: Fat-soluble vitamin and mineral supplements
Treatment of Respiratory features of CF: mucus obstruction
Airway clearance via physiotherapy, Mucolytics and Bronchodilators
Treatment of Respiratory features of CF: mucus obstruction
Airway clearance via physiotherapy, Mucolytics and Bronchodilators
Treatment of Respiratory features of CF: infection
antibiotics
oral, IV or nebulised
Treatment of Respiratory features of CF: increased inflammation
azithromycin
