Cystic Fibrosis Flashcards
what does the CF gene code for?
a protein called cystic fibrosis transmembrane regulator
Where is the CFTR largely expressed? (5)
epithelial cells of the airways, pancreas, biliary system, GU system, sweat glands (All organs that involve mucus)
How does genotype help to predict the severity of lung disease and liver disease in CF?
genotype cannot predict severity
what is the most common mutation in CF?
deltaF508
Compare the prevalence of CF disease (how many in US) vs the number of Americans that are unknowing carriers
CF rare disease, only 30,000 US ppl have it
but 10 mil unknowing carriers
just know there is a diff here
what race is CF a disease of
whites
What is the inheritance pattern of CF?
Auto Recessive - 2 carrier parents - 25% chance of having affected child (full blown cf)
where is the CFTR gene located? chromosome and arm
CFTR is on long arm of chromosome 7 (this will be on exam)
what is the function of the CFTR protein? where is it located?
CFTR is located at the cell surface and acts as a regulated chloride channel
what percentage of CF patients have at least one copy of F508 del? i.e. either homozygous for F508 or heterozygous for it
87% (common things are common, so impt to remember F508)
48% homozygous for df508 mutation. NEED TO KNOW THIS
under normal conditions, what does CFTR inhibit
it inhibits the ENaC sodium channels (that would bring sodium into epithelial cells)
what happens regarding ENaC and the airway surface liquid when the CFTR is mutated/non functional
ENaC is not inhibited
sodium absorption is inc
Water follows sodium
ASL volume decreases - mucus is dehydrated and thick
Molecular consequences of CFTR mutations fall into 5 classes. what are they (briefly)? which one is deltaF508?
Class I - no synthesis (hardest to treat)
Class II - block in processing, cannot get to membrane (F508)
Class III - V - CFTR at surface cell membrane, but either non functional or reduced function
of the exocrine glandular ducts where CFTR is present (pancreas, lungs, sweat glands, glands of uterine cervix), which ducts are not obstructed in CF
uterine cervix glands
not obstructed
this is a shitty question - but the shit below explains the salty sweat
in the sweat gland, both the Cl and Na channel face the same direction, inward. If the CFTR is mutated, then you cannot reabsorb Cl or Na - leads to salty sweat
Oppo of lung and all the other epithelial tissues, where CFTR and ENaC are facing opposite directions
What is the symptom/condition that can be seen in infants w/ CF that help w/ diagnosis of an infant (probably the most common presenting condition of CF in kids)
meconium ileus - present as abdominal pain - due to pancreatic insufficiencies associated with CF
what are some general symptoms of CF seen in infancy
stools that are pale, foul or float
wheezing, pneumonia
salty-tasting skin
chronic cough
in classic CF
1) what is the activity of CFTR?
2) what upper respiratory symptoms will you see?
3) what other symptoms?
4) what test do you do?
5) what is generally age at diagnosis?
1) no CFTR at all
2) chronic sinusitis, severe bacterial infection of lungs
3) hepatobiliary disease, pancreatic exocrine insufficiency* - leads to malabsorption, meconium ileus at birth*
4) sweat chloride test
5) usually dx young
In non classic CF
1) most common symptoms
2) other variable chronic symptoms
3) pancreatic status
4) sweat chloride
5) age at dx
1) asthma-like sinopulmonary symptoms - also nasal polyps
2) chronic bacterial infxn of lungs - variable, later onset
3) Pancreas is still sufficient
4) sweat chloride - less elevated, but still up
5) dx later in life 25-30 ish - b/c they retain pancreatic function