Written by epgonline.org - Last updated 29 May 2018
Cystic fibrosis (CF) is an autosomal recessive, life-limiting, genetically inherited disease. It is a multi-system disorder and results from one of several identified mutations in the gene responsible for coding the cystic fibrosis transmembrane conductance regulator (CFTR). It is most common in populations of European descent, in whom approximately 3–4% of the population are carriers, while it is least common in Asian and African populations.
The defective protein is a transmembrane chloride channel, and exists within multiple organ systems. In modern medicine, the most common life limitation is secondary to lung disease – the chloride channel in this case is a key component of the mucocilliary elevator, part of the innate immune system which clears mucus and pathogens from the airways. In CF the mucus is much thicker, causing ‘plugging’ of airways, and is unable to be easily cleared by cilia. Recurrent infections cause progressive damage over time, with colonisation by pseudomonas species typically occurring by 18 years of age. Other notably affected organ systems are:
- gastrointestinal – thicker meconium potentially causing bowel obstruction in neonates
- pancreas – exocrine deficiency requiring oral replacement, and endocrine deficiency resulting in diabetes
- reproductive – males often have bilateral absence of the vas deferens, female have reduced fertility due to thickened cervical secretions
- sweat glands – high salt loss, this forms the basis for childhood screening
The mainstay of treatment for CF at present revolves around managing complications as they arise. There are numerous treatments either in development, or recently approved, which aim to improve CFTR function or expression – these and similar treatments may have a significant impact for people with CF in the future.
Prognosis has improved hugely, but is still far short of a full lifespan. The average survival for a patient with CF in the 1950s was measured in months rather than years, whilst today life expectancy in developed countries is around 40 years and continuing to improve.
Elborn JS. Cystic Fibrosis. Lancet. 2016; pii: S0140-6736(16)00576–6.
Nazareth D, Walshaw M. Coming of age in cystic fibrosis – transition from paediatric to adult care. Clin Med 2013;13:482–486.