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  1. How do mutations in the cystic fibrosis (CF) gene relate to the clinical manifestations of the disease?

  2. What criteria help determine when a CF patient should be admitted to hospital for respiratory complications of the disease?

  3. What treatment modalities are most effective in restoring lung function to baseline for CF respiratory exacerbations?

  4. Why is CF–related diabetes (CFRD) one of the most important comorbidities in CF and how does it alter the course of the disease?

  5. What are the most effective treatment modalities for the two most common pulmonary complications of CF: massive hemoptysis and pneumothorax?

Definition and Overview

Cystic fibrosis (CF) is an autosomal recessive disease due to mutations in the CF transmembrane conductance regulator (CFTR) gene. The CFTR gene is expressed in epithelial cells in a variety of organs including the lung, sinuses, pancreas, sweat gland, intestine, liver, and vas deferens, and thus CF is a mulitorgan disease. CF is the most common inherited life-shortening disease of Caucasians in the United States. More than 90% of the morbidity and the mortality is due to lung disease. CF lung disease is characterized by the triad of altered mucociliary clearance, chronic polymicrobial infection of the airways, and an exaggerated inflammatory response. The ultimate outcome of CF lung disease is destruction of the normal airway architecture and death due to respiratory failure.

With therapy, primarily aimed at slowing the progression of lung disease and improving nutrition, median survival is approaching 40 years of age. Unfortunately, there is no cure for CF. The average CF adult can expect to spend 2 to 3 hours a day taking a variety of inhaled medications, ingest 30 to 50 pills per day, and be hospitalized about once per year for a period of 1 to 3 weeks. Even with insurance, most CF patients have out-of-pocket health care costs approximating $10,000 per year.

However, there are a significant number of CF patients who have normal lung function, rarely require hospitalizations, and need only a few medications to control their disease. Thus, there can be tremendous variability in the severity of the pulmonary phenotype in this monogenic disease ranging from death in childhood due to respiratory failure to living to retirement and the thought of enjoyment of family and friends as old age ensues.

Genetic Epidemiology—Incidence and Ethnic Distribution

The incidence of CF varies tremendously according to ethnicity. Also, those countries, such as the United States, that have universal newborn screening for CF will have more accurate measures of incidence than those countries that do not. CF occurs in about 1 in 3500 white births, 1 in 17,000 African Americans, and 1 in 90,000 Asians in Hawaii. Once considered a disease affecting only children, the life expectancy in CF has increased dramatically in the past 3 decades. Now 41% are over 18 years of age, and median predicted survival has increased from 28 years for ...

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