8. Cystic Fibrosis

Question 1

What does CF lead to an abnormal function of?

Answer 1

Epithelial chloride channel - cystic fibrosis transmembrane conductance regulator (CFTR)
Present in lungs, pancreas, liver, sweat glands, vas deferens

Question 2

What is the role of CFTR?

Answer 2

Transmembrane protein that transports chloride and bicarbonate and also regulates the ENAC
Enables Cl to be transported out of cells into airways, transport of Cl helps control movement of water
Also regulates Na rebasorption into cells
Therefore plays critical role in hydration of mucous at surface of airways track

Question 3

What are the possible effects of mutations on CFTR?

Answer 3

Manufacture of CFTR protein
Transportation of CFTR
CFTR processing function
CFTR stability at cell membrane

Question 4

What is the most common mutation and what does that do?

Answer 4

Phe508del CFTR protein
Causes defective intracellular processing and trafficking
Decreased stability, which drastically reduces quantity of CFTR protein at apical surface of epithelial cells
Also exhibits defective channel gating

Question 5

How is CF diagnosed?

Answer 5

One or more of characteristic phenotypic features or a history of CF in a sibling or a positive newborn screening test result
And sweat test or identification of 2 CF mutations

Question 6

What is the main CF clinical presentations?

Answer 6

Meconium ileus - bowel blocked by sticky secretions in newborn
Intestinal malabsorption - severe deficiency of pancreatic enzymes secondary to blockage of exocrine glands
Recurrent chest infections
Newborn screening

Question 7

When should you consider atypical late diagnosis of CF?

Answer 7

Recurrent idiopathic pancreatitis
Recurrent sinusitis and lung infections
Infertility
Allergic bronchopulmonary aspergillosis

Question 8

What are the lung complications of CF?

Answer 8

Bronchiectasis
Pneumothorax
Haemoptysis
Respiratory failure

Question 9

What are nasal/upper respiratory tract complications of CF?

Answer 9

Chronic sinusitis

Nasal polyposis

Question 10

What are the pancreas complications in CF?

Answer 10

DM

Pancreatic insufficiency

Question 11

What are the gut complications of CF?

Answer 11

Distal intestinal obstruction syndrome

Oesophageal reflux/oesophagitis

Question 12

What are the lover complications of CF?

Answer 12

Chronic liver disease

Portal hypertension

Question 13

What are the biliary tree complications of CF?

Answer 13

Gallstones

Question 14

What are the heart complications of CF?

Answer 14

Cardiac failure

Question 15

What are the joint and bones complications of CF?

Answer 15

Arthritis

Osteoporosis

Question 16

What are the reproductive tract complications of CF?

Answer 16

Male infertility

Congenital bilateral absence of vas deferens

Question 17

What lifestyle advice is given to CF patients?

Answer 17

No smoking
Avoid other CF patients
Avoid people with colds or infections
Avoid jacuzzis
Lean and dry nebulisers thoroughly 
Annual influenza immunisation and pneumococcal vaccine
NaCl tablets

Question 18

What is the management in CF?

Answer 18

Optimal nutritional state
Maintaining lung health - chest physio, infection management
Vaccinations
Multisystem focus

Question 19

What contributes to impaired nutritional status in CF?

Answer 19

Pancreatic insufficiency
Chronic malabsorption
Chronic inflammation leading to increased energy expenditure
Increased energy requirements of breathing
Suboptimal nutrient intake related to impaired taste, fatigue