Cystic fibrosis (CF) is an autosomal recessive genetic condition affecting mucus glands.

Epidemiology

• Caucasian>afro-caribbean>Asian
• 1/25 carry the defective gene
• 1/2500 live births
• 10,600 patients in the UK
• Life expectancy = 51-52 years

Pathophysiology

Defect in the cystic fibrosis transmembrane regulator (CFTR) gene on chromosome 7 causes CF

• This is the name of the gene itself and the protein that it codes for
• The protein sits in the epithelial membranes and allows Cl transport across it, this allows Na transport and water transport. Defects = thick secretions due to no osmotic drive
• delta-F508 - most common mutation
• Most severe mutation: G542X - results in no synthesis of CFTR

Overall effect of this defect:

• Thick secretions in the mucous, saliva, tears, sweat and digestive enzymes - more viscous

The key consequences of the cystic fibrosis mutation are:

• Thick pancreatic and biliary secretions that cause blockage of the ducts, ****resulting in a lack of digestive enzymes such as pancreatic lipase in the digestive tract (85% of CF patients have exocrine dysfunction)