Cystic Fibrosis

Question 1

What is cystic fibrosis? Inheritance pattern? What gene? What defect? What does this lead to?

Answer 1

Autosomal recessive
All babies screened at birth
Mutation in CF transmembrane conductance regulator (CFTR) gene on chromosome 7.
Cl- channel - defect leads to a combination of defective chloride secretion and increased sodium absorption across the airway epithelium.
Changes in composition of airway surface liquid predispose lung to chronic pulmonary infection and bronchiectasis.

Question 2

Clinical features of CF?

Answer 2

Neonate: failure to thrive, meconium ileus (first poo not passed), rectal prolapse

Children and young adults:
Resp: cough, wheeze, recurrent infection, bronchiectasis, pneumothorax, haemoptysis, resp failure, cor pulmonale

GI: Pancreatic insufficiency (DM, steatorrhea), distal intestinal obstruction, gallstones cirrhosis

GU: male infertility

Osteoporosis, arhritis, vasculitis

Question 3

How is CF diagnosed?

Answer 3

Sweat test: sweat sodium and chloride > 60mmol/L chloride is usually > sodium
Genetics screening for common mutations.

Question 4

What tests for CF?

Answer 4

Bloods: FBC, U&E, clotting, vitamin A, D ,E, glucose tolerance test
Imaging: Radiology, abdo USS
Other: spirometry - obstructive

Question 5

How is CF managed?

Answer 5

MDT
Chest - physiotherapy - postural drainage and chest clearance techniques
Abx for infections
Mycolytics
Bronchodilators

GI: Pancreatic enzyme replacements, vitamin supplements

treat complications