Cystic Fibrosis Flashcards
What is cystic fibrosis?
- an inherited genetic disorder
- causes thick mucus
- mucus damages lungs, pancreas and GIT
What is the most common inherited genetic condition in the UK?
- cystic fibrosis
Cystic fibrosis is an autosomal recessive disorder, but what does that mean?
- autosomal = non sex chromosomes
- both parents must be carries for the cystic fibrosis transmembrane protein regulator (CFTR) gene
- 1/4 chance of child having CFTR gene mutation

Cystic fibrosis is an autosomal recessive disorder, meaning both parents have the cystic fibrosis transmembrane protein regulator (CFTR) gene, but out of children they may have, which children would have cystic fibrosis?
1 - child receives CFTR gene from both parents = CF
2 - child receives 1 CFTR gene from 1 parent = no CF
3 - child receives no CFTR gene from parents = no CF
Out of 25 people in the UK, how many are carriers for the cystic fibrosis transmembrane protein regulator (CFTR) gene?
- 1:25 people are carriers
In the UK how many births out of 2500 are born with cystic fibrosis?
- 1:2500 babies
- 0.04%
What % of Caucasians in the UK account for the 9000 individuals in the UK with CF?
- 97%
What chromosome is the cystic fibrosis transmembrane protein regulator (CFTR) gene located on?
- chromosome pair 7
- long arm of the chromosome = q
- band 3
- sub band 1
- 7q31
The cystic fibrosis transmembrane protein regulator (CFTR) gene is a specific code, what does this code allow the cell to do?
- transcribe protein
- synthesis protein and then fold transmembrane protein
What is the most common CF gene?
- phenylalanine at position 508 of the CFTR protein
- written as ΔF508
Roughly how many different versions of the cystic fibrosis transmembrane protein regulator (CFTR) gene are there?
- 1700
What is the main function of the cystic fibrosis transmembrane protein regulator (CTFR)?
- controls Cl- in and out of the cell
- activated by cyclic adenosine monophosphate (cAMP)
- ATP mediated

In a healthy person how does cystic fibrosis transmembrane protein regulator (CTFR) function?
- Cl- secreted by mucous secreting epithelial cells
- Cl- attracts H2O ⬇️ viscosity of mucus

Why is it important for mucus not to be to thick in relation to cilia?
- cilia need to move freely like seaweed in ocean
- move particles that could be dangerous out of lungs
In CF what happens to mucus secreting epithelial cells?
- Cl- not released
- mucus becomes very viscous
- cilia cannot work

In addition to the cystic fibrosis transmembrane protein regulator (CTFR) not functioning or even being present, what happens to extracellular Na+ levels?
- cystic fibrosis transmembrane protein regulator (CTFR) inhibits Na+ from entering the cell freely
- ⬆️ Na+ inside cell attracts water and further ⬆️ mucus viscosity

Problems with the cystic fibrosis transmembrane protein regulator (CTFR) can occur at a number of locations inside the cell, what are these locations?
1 - nucleur = mutations in CFTR gene
2 - translation and processing = incorrect folding
3 - transport to membrane
4 - insertion of CFTR into membrane

What is potentially the most common location inside the cell where CFTR is impaired?
- during translation and folding - class 2
How many classes of faulty CFTR proteins inside the cell?
- 4 classes - 1-4
If the mucus is highly viscous and the ciliary are unable to function in the lungs what does that do to the risk of infection in CF patients?
- ⬆️ risk of infection - mucus acts as a medium for infections
Does CF just affect the lungs?
- no - multi-systemic disease
What are the main organs affected by CF?
- lungs - pancreas - GIT
What is bronchiectasis?
- chronic enlargement of airways of the lungs
- increased airways size is filled with mucus
- affects the smalled airways (between bronchi and terminal bronchi)

What can bronchiectasis do to the lungs?
- inflammation and damage
- cilia damaged
- enlarged airways blocked with mucus ⬆️ air trapping
- obstructive lung disease
Is bronchiectasis classed as restrictive or obstructive lung disease?
- obstructive
In CF patients experience lots of infections, if these infections are not managed well, what can this cause?
- type 2 respiratory failure
The pancreas is affected by CF, what is exocrine insufficiency?
- inability to secrete digestive enzymes
The pancreas is affected by CF, what is endocrine insufficiency?
- inability to secrete insulin and glucagon - diabetes
If the pancreas does not work properly what can happen to the patient?
- poor nutrition - malabsorption - failure to thrive
In patients with CF what is common on their skin?
- ⬆️ Cl- levels - one of diagnostic tests
Is reproduction affected in patients with CF?
- some may experiences infertility issues
In the upper respiratory tract of CF patients what is commonly found?
- chronic sinus disease
- nasal polyps

In the lower respiratory tract of CF patients what is commonly found?
- chronic cough and sputum
- bronchiectasis (dilated and inflamed bronchii)
- chronic suppurative lung disease (purlent pus)
- colonisation with pathogenic bacteria
- respiratory infections
- clubbing
What are the 4 most common bacteria that can colonise and cause infections present in CF patients?
1 - staphylococcus aureus
2 - haemophilus influenza
3 - pseudomonas aeruginosa (Gram -)
4 - burkholderia cepacia (Gram -)
In patients with CF, are chest X-rays normal?
- no abnormal - dilation of bronchi - hyperinflammation (as obstructive)
In patients with CF does the lack of digestive enzymes affect stool?
- ⬆️ fat content in stool
- steatorrhoea (stool is pale and floats)
- ⬇️ H2O content ⬆️ risk of bowel obstruction
In patients with CF does the lack of digestive enzymes and chloride affect bowel movements?
- ⬇️ H2O in bowel - ⬆️ constipation and bowel obstruction
What is the meconium ileus?
- first bowel movement of a baby
- thick mucus lining GIT
- M = think M for Mucus
What are some fat soluble vitamins patients with CF may have a deficit in?
- ADEK - Vitamines A, D, E and K
Is the liver affected in patients with CF?
- liver cirrhosis may occur
In addition to physiological affects, do patients with CF require any further support?
- social - pyschological
What support can potential parents seek if they are planning a pregnancy and fear they may pass on CF to their baby? (Antenatal)
- yes - parents screened for CTFR gene - genetic counselling
If a woman is pregnant what prenatal support can she get if she suspects she suspects here baby has CF?
- DNA analysis of chorionic villi - amniocentesis
Once a child is born what tests can be performed quickly to diagnose the baby?
- Guthrie test
- heal prick to check for disease
- Sweat test
- Cl- levels in sweat
What is the threshold for the Cl- sweat test?
- >60mmol/L is abnormal
How can nasal cell epithelium help diagnose babies with CF?
- ⬆️ goblet cell hyperplasia - ⬆️ mucus production - ⬆️ thickness of mucus
How has genetic testing helped with CF?
- screen WGS - better detection - earlier treatment
Why are antibiotics given orally and intravenously in patients with CF?
- fast acting
- repeated respiratory infections
- systemic effects
Why do patients with CF receive extensive chest physiotherapy?
- help breathe - cough up mucus
What is DNAse?
- enzyme able to degrade DNA
- specifically phosphodiester bonds between nucleotides
How does DNAase help patients with CF as a potential treatment?
- degrades DNA from dead inflammatory cells - thins mucus
How is DNAase administered in patients with CF?
- high concentrations - in nebulisers
What else are CF patients prescribed in an attempt to thin the mucus?
- mucolytic drugs
Are CF patients prescribed anything similar to other obstructive lung disorders?
- bronchodilators - long term O2 therapy
In extreme cases, what can be the last course of treatment in patients with CF?
- lung transplant
What can CF patients be prescribed to treat exocrine insufficiency?
- creon (pancreatic enxymes)
- multivitamins
- nutritional support
What can CF patients be prescribed to treat endocrine insufficiency?
- insulin
What is creon that CF patients are prescribed?
- synthetic mixture of enzymes - usually amylase, lipase, and protease
What has increased life expectancy in patients with CF?
- improved diagnosis - improved treatments