Cystic Fibrosis Flashcards
**What is the most common deletion leading to cystic fibrosis?
• where is this gene located?
∆F508 is the most common gene to be deleted in cystic fibrosis it is located on chromosome 7. (the deleted phenyalanine is a result of an AA deletion in the mRNA/DNA code)
**What is the basic reason why people with cystic fibrosis get sick?
They have thick mucous that their cilia can’t clear. Its thick due to a dysfunctional chloride transporter (CFTR) that fails to pump Cl- out of the cell. The CFTR channel acts to regulate ENaC and prevents ENaC from reabsorbind Na+ into the cell. without regulation ENaC takes in Na+ and water follows Na+ inside
**What gives you the worst prognosis as a CF patient?
• Other bad prognostic indicators?
1 is infection by burkholderia cepacia
- *Others:**
- *• Mucoid Pseudomonas a. and Pseuomonas a. infections**
• FEV1 less than 30% means LUNG TRANSPLANT LIST, less then 50% 2yr survival rate
• Inability to absorb fat => INDICATES pancreatic dysfunction
**What deficiencies will you develop if you can’t absorb fat?
• Fat Soluble vitamins will become deficient (A, E, D, K)
**What happens when you’re deficient in vitamin:
• A
• E
• D
• K
• A - squamous metaplasia on the retina
• E - ataxia and chronic liver disease causing neurological symptoms
• D - osteomalacia/ricketts
• K - clotting enzyme deficiencies
Why might a kid with cystic fibrosis be more likely to die of hemmorhage?
Vitamin K deficiency leads to lack of clotting factors II, VII, IX, X as well as protein C and S.
**Why are males with CF infertile?
• are females also infertile?
Males with CF = infertile because they fail to develop a vas deferens
Females are Fertile but might have difficulty concieving due to thickened mucous secretions
**What test helps to diagnose CF?
• what are the cut off values for this test?
**Sweat chloride
More than 60 + frequent infections, and cough = diagnostic
40-60 + symptoms = more testing
less than 40 = no CF
**What is the standard treatment for CF?
• what is the reason for each of these therapies?
Standard treatment = Tobramycin + Dornase alpha + hypertonic saline
- Tobramycin - prevents colonization with Ps. aeruginosa that is impossible to erradicate
- Domase alpha (pulmozyme)- is a DNAase that breaks up DNA that builds up in the lungs from dead neutrophils, bacteria, etc.
- Hypertonic Saline - induces hydration and coughing to move mucous out of airways
Why has the number of CF patients in the world risen in recent years?
We have better methods of diagnosis and treatment for these patients
What ethnic group gets CF?
• what is the prevalence of carriers and incidence?
About 1/30 caucasians carry the gene with 1/3300 being affected, this is the ethnic group with the highest incidence.
At what stage does the CFTR protein get held up in the ∆F508 deletion?
• why?
Held up in the ER because it lacks F, NEVER MAKES it to the surface
What are some key clinical features to look for in a patient with CF?
Pansinusitis with CF pathogens = UNIVERSAL FINDING
Endobronchial Disease:
• Cough/sputum production => Hemoptysis
• Air obstruction – Wheezing, Obstruction on PFTs
• CXR abnormalities
• DIGITAL CLUBBING
Nasal Polyps = 30% of CF patients
Would you expect people with CF to present as having more of a restrictive or obstructive pattern on their PFTs?
PFTs would reveal OBSTRUCTIVE pattern
*They’re chronically infected and have thick mucous and they are also going to get bronchietasis which is a category of Obstructive disease
What are you most likely to die of if you have CF?
• why does this disease become harder to control has patients age?
Pulmonary Complications
•Disease becomes harder to control becauseinflammation and collagen deposition (scarring) make tissue unresponsive to bronchodilators
Is this symptom specific to cystic fibrosis?
NO clubbing is not specific to CF, but many patients experience it because its associated with cardio-pulmonary disease
What is seen here?
Bronchietasis
What is this CT showing?
Distal Intestinal Obstruction Syndrome (DIOS) - thick mucous in the GI tract may lead to stool getting stuck in adults (children may get meconium ileus)
