Cystic Fibrosis Diagnosis in Newborns, Children, and Adults

Carlo Castellani, MD; Barry Linnane, MB, BCh, BAO, DCH, MRCPI, MRCPCH, MD; Iwona Pranke, PhD; Federico Cresta, MD; Isabelle Sermet-Gaudelus, MD, PhD; Daniel Peckham, MD


Semin Respir Crit Care Med. 2019;40(6):701-714. 

In This Article

Diagnostic Tools

CF is associated with loss-of-function mutations in the gene encoding the CFTR protein, which acts as a chloride (Cl) channel after activation by protein kinase A.[140] Classically, the diagnosis is straightforward, based on a characteristic clinical picture, including chronic bronchitis and pancreatic insufficiency, together with a sweat Cl concentration greater than 60 mmol/L or the identification of two CF-causing mutations or both.[94,138] Clinicians, however, encounter a significant number of patients who have suggestive clinical features but do not meet the current diagnostic criteria for CF because of sweat Cl levels in the intermediate range and at least one CFTR mutation of uncertain clinical relevance. In these situations, the study of CFTR function and extensive genetic screening may help to reach a definitive diagnosis.[141]