Cystic fibrosis

Question 1

Cystic Fibrosis : Genetics

Answer 1

• Autosomal recessive disorder of the CFTR gene codes for the CFTR protein
• More common in people of European descent

Question 2

Cystic fibrosis : Pathophysiology

Answer 2

• CFTR protein is a channel protein that pumps chloride ions as a result draws water into the secretions which thins them out
• ∆F508 - most common mutation which misfiles CFTR protein and can’t migrate from the endoplasmic reticulum onto the epithelial surface
• thus cannot pump chloride ions on - leading to a lack of water and overly thick secretions.

Question 3

Cystic fibrosis : Clinical features - Early Childhood

Answer 3

1. Pancreatic insufficiency secondary to thick secretions in the pancreatic ducts
2. Preventing digestive enzymes to enter the small intestines
3. As a result protein and fat from the diet are not absorbed

Leading to the following clinical features;
* poor weight gain
* failure to thrive
* steatorrhea secondary to fat malabsorption
* Pancreatitis and insulin dependant diabetes.

Question 4

Cystic fibrosis : Clinical features - Systemic

Answer 4

1. Repeated chest infections
2. Infertility in men - lack vasdeferens which transport the sperm from the testes
3. Digital clubbing
4. Nasal polyps

Question 5

Cystic fibrosis : Pneumonia

Answer 5

Thick mucus on the cilia result in bacterial colonisation of the lungs which increases bacterial load } recurrent chest infections

Pneumonia - due to bacterial colonisation
* common infections are from Stayphyloccus aureus (Gram +) and Pseudomonas aeruginonosa (G-).
* Bronchiectasis 2nd to repeated chest infection

Question 6

Cystic fibrosis : Management

Answer 6

1. Regular chest physiotherapy
2. High calorie diet including vitamin supplementation and pancreatic enzyme with meals
3. Patients with CF to minimise contact with eachother to prevent cross infection of bacteria
4. Lung transplantation