May is cystic fibrosis (CF) awareness month. CF is a genetic disorder of autosomal-recessive inheritance pattern that primarily impacts Caucasians, Hispanics to a lesser degree, and rarely other races.  The disorder affects 1 in 3,000 Caucasians, with 1 in 25 being a carrier of the gene. 

CF causes abnormally thick mucus production due to abnormalities in the cell membrane CFTR protein. This prevents normal transportation of chloride and water across the cell membrane, leading to abnormally thick secretions.  Manifestations can differ based on genetic mutation and phenotypic variation within the genetic mutation. There are over 1,000 different mutations. The most common mutation is the D F508 mutation, impacting 60% of patients.

The increased viscosity makes expectoration of respiratory tract secretions difficult and cilia often become immobilized.  Trapping of secretions within the respiratory tract increases risk of infection. Patients with CF often develop bronchiectasis and chronic lung infections with bacteria such as Pseudomonas aeruginosa.  Patients with CF demonstrate a mixed obstructive and restrictive pattern on pulmonary function tests with a reduced FEV1, FVC, and TLC.  In addition to the respiratory symptoms, exocrine and endocrine pancreatic insufficiency are of significant clinical concern. Patients with CF also commonly demonstrate infertility, sinusitis, nasal polyps, and may develop cirrhosis and cholelithiasis.

CF was previously a fatal disease, with an average survival of age 2.  The cause of death is typically associated with pulmonary complications. Treatments are rapidly evolving and include those to restore CFTR function. The average life expectancy now exceeds age 39.  Please see the CF Foundation’s drug development pipeline for the latest information on approved treatments in CF.

Read more:

Current Medical Diagnosis & Treatment 2018, Chapter 9: Pulmonary Disorders

Principles and Practices of Hospital Medicine, 2e: Chapter 234: Cystic Fibrosis

Cystic Fibrosis Foundation