Cystic Fibrosis Flashcards
What is the most common autosomal recessive disorder in Caucasians?
Cystic fibrosis
What is the main cause of morbidity and mortality in CF?
Pulmonary (lung) disease
What causes 90% of deaths in CF?
Respiratory failure
If both parents are carriers, what’s the probability of a child being affected?
1 in 4
If both parents are carriers, what’s the probability of a child being a carrier?
2 in 4
If both parents are carriers, what’s the probability of a child being unaffected?
1 in 4
How does CF occur?
Due to mutation in the transmembrane regulator protein which is coded on chromosome 7
What happens as a result of abnormal transport chloride and sodium?
Reduced airway surface liquid
Thick sticky mucous
Shearing
Impaired bacterial killing via neutrophils
How many mutation classes are there in cystic fibrosis?
6
What are the mutation classes for CF based on?
Synthesis
Processing/trafficking
Function of CFTR
What is the most common mutation type?
Delta F508
How is CF diagnosed?
Pre-implantation genetic diagnosis
Chorionic villus sampling
Amniocentesis
Guthrie test - newborn bloodspot day 5
What does a sweat test measure?
Measures the concentration of chlorides exerted in sweat.
It’s often elevated in CF
How many diagnostic outcomes do prenatal, antenatal and postnatal testing give you?
3
CF
NOT CF
CF - screen positive inconclusive diagnosis
Where can CF affect?
Anywhere in the body (multisystem disease)
What is pancreatic insufficiency?
- The CTFR mutation also affects the pancreas
- The pancreas produces enzymes that digest food. Lack of enzymes causes: malabsorption, abnormal stools (pale, float), failure to thrive
- Importance of record, growth charts
what are the classes of pancreatic function?
6 classes of CF disease Thus 6 levels of function in the pancreas - class 1-3 are pancreas insuffiencent - class 4-6 have some pancreatic function
What percentage of CTFR is needed to have sufficient pancreatic function and be asymptomatic?
5%
What is recurrent bronchopulmonary infection?
Pneumonia
Bronchiectasis
Scarring
Abscesses
What does a CTFR abnormality cause?
Abnormal electrolyte transport across cell membrane
Dehydration of airway surface layer (allows mucous to slide across airways and be coughed up)
Decreased mucociliary clearance
Mucous sticks to the mucosal surface and causes shearing damage
Increased bacterial adherence
Decreased bacterial killing
How do CF patients get repeated respiratory infections?
Vicious circle of events
What happens as a result of recurrent chest infections?
They get progressive respiratory decline.
What signs of CF does CT show?
Tramlines
Signet rings
Mucous plugging
Consolidation
How is CF managed?
It is multi organ disease and needs and MDT to improve long term outcome.
