Cystic Fibrosis

Gregory S. Montgomery; Michelle Howenstine

doi:10.1542/pir.30-8-302

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Gregory S. Montgomery, MD*
Michelle Howenstine, MD†

^*Assistant Professor of Clinical Pediatrics
^†Professor of Clinical Pediatrics, Indiana University School of Medicine, Indianapolis, Ind

Objectives

After completing this article, readers should be able to:

Describe the underlying genetic disruption that leads to the pathophysiologic changes seen in cystic fibrosis (CF).
Interpret newborn screening results and other tests used to diagnose CF.
Recognize the complications that may arise in various organ systems of patients who have CF.
Discuss a range of treatments for CF.
Understand the philosophies of care that have improved the outcomes of those who have CF.

Introduction

CF is the most common fatal inherited disorder among whites, with more than 30,000 affected individuals living in the United States. CF recently has been recognized more commonly within many nonwhite populations. The defect causing CF is found in a single gene that changes the function of mucosal epithelial cells in the airways, pancreatic ducts, biliary tree, intestines, vas deferens, and sweat glands. Such impairment within any of these organ systems results in manifestations of CF disease that can vary both in complexity and severity. Classic CF disease is notable for an elevated sweat chloride concentration, progressive obstructive lung disease, and pancreatic insufficiency, which has associated protein and fat malabsorption that leads to clinically significant malnutrition.

Genetics and Epidemiology

CF is an autosomal recessive disorder caused by mutations of both alleles of the large, 250,000-base-pair gene located on chromosome number 7 called the cystic fibrosis transmembrane conductance regulator (CFTR). The CFTR protein is a cAMP-regulated chloride channel that usually resides within the apical portion of mucosal epithelial cells. The most common defect, named deltaF508, is caused by a deletion of three base-pairs and results in the absence of phenylalanine at codon 508. The mutation is present in 70% of those who have CF. One in 3,500 newborns is affected by CF. Whites are affected most frequently, followed by the Hispanic population. CF occurs infrequently in the African American population, with …