CFTR and cystic fibrosis: Cystic fibrosis (CF) is an autosomal recessive genetic condition caused by mutations in the gene encoding the CF transmembrane regulator (CFTR) that affects around 10 000 people in the UK.1, 2 CF is a multisystem condition1 but lungs are the main organ affected, with CFTR dysfunction causing abnormal airway surface liquid.1, 3 People with CF are particularly susceptible to infection causing acute deterioration in lung health (i.e. pulmonary exacerbations), which leads to progressive lung damage and eventually respiratory failure.4